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Title: The Geographical Distribution of Animals, Volume 1

Author: Alfred Russel Wallace

Release date: February 6, 2018 [eBook #56506]

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK THE
GEOGRAPHICAL DISTRIBUTION OF ANIMALS, VOLUME 1 ***

Transcriber's The Errata (after the List of Plates) have been worked
note: into the main text and appear like this. All other
apparent mistakes have been retained as printed.

THE GEOGRAPHICAL

DISTRIBUTION OF ANIMALS

WITH A STUDY OF
THE RELATIONS OF LIVING AND EXTINCT FAUNAS
AS ELUCIDATING THE
PAST CHANGES OF THE EARTH'S SURFACE.

BY

ALFRED RUSSEL WALLACE,
AUTHOR OF "THE MALAY ARCHIPELAGO," ETC.

WITH MAPS AND ILLUSTRATIONS.

IN TWO VOLUMES.—VOLUME I.

London:
MACMILLAN AND CO.
1876.

[The Right of Translation and Reproduction is Reserved.]

LONDON:
R. CLAY, SONS, AND TAYLOR, PRINTERS,
BREAD STREET HILL.

P R E FA C E .

The present work is an attempt to collect and summarize the existing
information on the Distribution of Land Animals; and to explain the more
remarkable and interesting of the facts, by means of established laws of
physical and organic change.

The main idea, which is here worked out in some detail for the whole earth,
was stated sixteen years ago in the concluding pages of a paper on the
"Zoological Geography of the Malay Archipelago," which appeared in the
Journal of Proceedings of the Linnean Society for 1860; and again, in a
paper read before the Royal Geographical Society in 1863, it was briefly
summarized in the following passage:—

"My object has been to show the important bearing of researches into
the natural history of every part of the world, upon the study of its past
history. An accurate knowledge of any groups of birds or of insects and
of their geographical distribution, may enable us to map out the islands
and continents of a former epoch,—the amount of difference that exists
between the animals of adjacent districts being closely related to
preceding geological changes. By the collection of such minute facts,
alone, can we hope to fill up a great gap in the past history of the earth
as revealed by geology, and obtain some indications of the existence of

those ancient lands which now lie buried beneath the ocean, and have
left us nothing but these living records of their former existence."

The detailed study of several groups of the birds and insects collected by
myself in the East, brought prominently before me some of the curious
problems of Geographical Distribution; but I should hardly have ventured
to treat the whole subject, had it not been for the kind encouragement of Mr.
Darwin and Professor Newton, who, about six years ago, both suggested
that I should undertake the task. I accordingly set to work; but soon became
discouraged by the great dearth of materials in many groups, the absence of
general systematic works, and the excessive confusion that pervaded the
classification. Neither was it easy to decide on any satisfactory method of
treating the subject. During the next two years, however, several important
catalogues and systematic treatises appeared, which induced me to resume
my work; and during the last three years it has occupied a large portion of
my time.

After much consideration, and some abortive trials, an outline plan of the
book was matured; and as this is, so far as I am aware, quite novel, it will
be well to give a few of the reasons for adopting it.

Most of the previous writings on Geographical Distribution appeared to me
to be unsatisfactory, because they drew their conclusions from a more or
less extensive selection of facts; and did not clearly separate groups of facts
of unequal value, or those relating to groups of animals of unequal rank. As
an example of what is meant, I may refer to Mr. Andrew Murray's large and
valuable work on the Geographical Distribution of Mammalia, in which an
immense number of coloured maps are used to illustrate the distribution of
various groups of animals. These maps are not confined to groups of any
fixed rank, but are devoted to a selection of groups of various grades. Some
show the range of single species of a genus—as the lion, the tiger, the
puma, and a species of fox; others are devoted to sections of genera,—as
the true wolves; others to genera,—as the hyænas, and the bears; others to
portions of families,—as the flying squirrels, and the oxen with the bisons;
others to families,—as the Mustelidæ, and the Hystricidæ; and others to
groups of families or to orders,—as the Insectivora, and the opossums with

the kangaroos. But in no one grade are all the groups treated alike. Many
genera are wholly unnoticed, while several families are only treated in
combination with others, or are represented by some of the more important
genera.

In making these observations I by no means intend to criticise Mr. Murray's
book, but merely to illustrate by an example, the method which has been
hitherto employed, and which seems to me not well adapted to enable us to
establish the foundations of the science of distribution on a secure basis. To
do this, uniformity of treatment appeared to me essential, both as a matter
of principle, and to avoid all imputation of a partial selection of facts, which
may be made to prove anything. I determined, therefore, to take in
succession every well-established family of terrestrial vertebrates, and to
give an account of the distribution of all its component genera, as far as
materials were available. Species, as such, are systematically disregarded,
—firstly, because they are so numerous as to be unmanageable; and,
secondly, because they represent the most recent modifications of form, due
to a variety of often unknown causes, and are therefore not so clearly
connected with geographical changes as are the natural groups of species
termed genera; which may be considered to represent the average and more
permanent distribution of an organic type, and to be more clearly influenced
by the various known or inferred changes in the organic and physical
environment.

This systematic review of the distribution of families and genera, now
forms the last part of my book—Geographical Zoology; but it was nearly
the first written, and the copious materials collected for it enabled me to
determine the zoo-geographical divisions of the earth (regions and sub-
regions) to be adopted. I next drew up tables of the families and genera
found in each region and sub-region; and this afforded a basis for the
geographical treatment of the subject—Zoological Geography—the most
novel, and perhaps the most useful and generally interesting part of my
work. While this was in progress I found it necessary to make a careful
summary of the distribution of extinct Mammalia. This was a difficult task,
owing to the great uncertainty that prevails as to the affinities of many of
the fossils, and my want of practical acquaintance with Palæontology; but
having carefully examined and combined the works of the best authors, I

have given what I believe is the first connected sketch of the relation of
extinct Mammalia to the distribution of living groups, and have arrived at
some very interesting and suggestive results.

It will be observed that man is altogether omitted from the series of the
animal kingdom as here given, and some explanation of this omission may
perhaps be required. If the genus Homo had been here treated like all other
genera, nothing more than the bare statement—"universally distributed"—
could have been given;—and this would inevitably have provoked the
criticism that it conveyed no information. If, on the other hand, I had given
an outline of the distribution of the varieties or races of man, I should have
departed from the plan of my work for no sufficient reason. Anthropology is
a science by itself; and it seems better to omit it altogether from a
zoological work, than to treat it in a necessarily superficial manner.

The best method of illustrating a work of this kind was a matter requiring
much consideration. To have had a separate coloured or shaded map for
each family would have made the work too costly, as the terrestrial
vertebrates alone would have required more than three hundred maps. I had
also doubts about the value of this mode of illustration, as it seemed rather
to attract attention to details than to favour the development of general
views. I determined therefore to adopt a plan, suggested in conversation by
Professor Newton; and to have one general map, showing the regions and
sub-regions, which could be referred to by means of a series of numbers.
These references I give in the form of diagrammatic headings to each
family; and, when the map has become familiar, these will, I believe,
convey at a glance a body of important information.

Taking advantage of the recent extension of our knowledge of the depths of
the great oceans, I determined to give upon this map a summary of our
knowledge of the contours of the ocean bed, by means of tints of colour
increasing in intensity with the depth. Such a map, when it can be made
generally accurate, will be of the greatest service in forming an estimate of
the more probable changes of sea and land during the Tertiary period; and it
is on the effects of such changes that any satisfactory explanation of the
facts of distribution must to a great extent depend.

Other important factors in determining the actual distribution of animals
are, the zones of altitude above the sea level, and the strongly contrasted
character of the surface as regards vegetation—a primary condition for the
support of animal life. I therefore designed a series of six maps of the
regions, drawn on a uniform scale, on which the belts of altitude are shown
by contour-shading, while the forests, pastures, deserts, and perennial
snows, are exhibited by means of appropriate tints of colour.

These maps will, I trust, facilitate the study of geographical distribution as a
science, by showing, in some cases, an adequate cause in the nature of the
terrestrial surface for the actual distribution of certain groups of animals. As
it is hoped they will be constantly referred to, double folding has been
avoided, and they are consequently rather small; but Mr. Stanford, and his
able assistant in the map department, Mr. Bolton, have taken great care in
working out the details from the latest observations; and this, combined
with the clearness and the beauty of their execution, will I trust render them
both interesting and instructive.

In order to make the book more intelligible to those readers who have no
special knowledge of systematic zoology, and to whom most of the names
with which its pages are often crowded must necessarily be unmeaning, I
give a series of twenty plates, each one illustrating at once the physical
aspect and the special zoological character of some well-marked division of
a region. Great care has been taken to associate in the pictures, such species
only as do actually occur together in nature; so that each plate represents a
scene which is, at all events, not an impossible one. The species figured all
belong to groups which are either peculiar to, or very characteristic of, the
region whose zoology they illustrate; and it is hoped that these pictures will
of themselves serve to convey a notion of the varied types of the higher
animals in their true geographical relations. The artist, Mr. J. B. Zwecker, to
whose talent as a zoological draughtsman and great knowledge both of
animal and vegetable forms we are indebted for this set of drawings, died a
few weeks after he had put the final touches to the proofs. He is known to
many readers by his vigorous illustrations of the works of Sir Samuel
Baker, Livingstone, and many other travellers,—but these, his last series of
plates, were, at my special request, executed with a care, delicacy, and
artistic finish, which his other designs seldom exhibit. It must, however, be

remembered, that the figures of animals here given are not intended to show
specific or generic characters for the information of the scientific zoologist,
but merely to give as accurate an idea as possible, of some of the more
remarkable and more restricted types of beast and bird, amid the
characteristic scenery of their native country;—and in carrying out this
object there are probably few artists who would have succeeded better than
Mr. Zwecker has done.

The general arrangement of the separate parts of which the work is
composed, has been, to some extent, determined by the illustrations and
maps, which all more immediately belong to Part III. It was at first intended
to place this part last, but as this arrangement would have brought all the
illustrations into the second volume, its place was changed,—perhaps in
other respects for the better, as it naturally follows Part II. Yet for persons
not well acquainted with zoology, it will perhaps be advisable to read the
more important articles of Part IV. (and especially the observations at the
end of each order) after Part II., thus making Part III. the conclusion of the
work.

Part IV. is, in fact, a book of reference, in which the distribution of all the
families and most of the genera of the higher animals, is given in systematic
order. Part III. is treated somewhat more popularly; and, although it is
necessarily crowded with scientific names (without which the inferences
and conclusions would have nothing solid to rest on), these may be omitted
by the non-scientific reader, or merely noted as a certain number or
proportion of peculiar generic types. Many English equivalents to family
and generic names are, however, given; and, assisted by these, it is believed
that any reader capable of understanding Lyell's "Principles," or Darwin's
"Origin," will have no difficulty in following the main arguments and
appreciating the chief conclusions arrived at in the present work.

To those who are more interested in facts than in theories, the book will
serve as a kind of dictionary of the geography and affinities of animals. By
means of the copious Index, the native country, the systematic position, and

the numerical extent of every important and well established genus of land-
animal may be at once discovered;—information now scattered through
hundreds of volumes.

In the difficult matters of synonymy, and the orthography of generic names,
I have been guided rather by general utility than by any fixed rules. When I
have taken a whole family group from a modern author of repute, I have
generally followed his nomenclature throughout. In other cases, I use the
names which are to be found in a majority of modern authors, rather than
follow the strict rule of priority in adopting some newly discovered
appellation of early date. In orthography I have adopted all such modern
emendations as seem coming into general use, and which do not lead to
inconvenience; but where the alteration is such as to completely change the
pronunciation and appearance of a well-known word, I have not adopted it.
I have also thought it best to preserve the initial letter of well-known and
old-established names, for convenience of reference to the Indices of
established works. As an example I may refer to Enicurus,—a name which
has been in use nearly half a century, and which is to be found under the
letter E, in Jerdon's Birds of India, Blyth's Catalogue, Bonaparte's
Conspectus, and the Proceedings of the Zoological Society of London down
to 1865. Classicists now write Henicurus as the correct form; but this seems
to me one of those cases in which orthographical accuracy should give way
to priority, and still more to convenience.

In combining and arranging so much detail from such varied sources, many
errors and omissions must doubtless have occurred. Owing to my residence
at a distance from the scientific libraries of the metropolis, I was placed at a
great disadvantage; and I could hardly have completed the work at all, had I
not been permitted to have a large number of volumes at once, from the
library of the Zoological Society of London, and to keep them for months
together;—a privilege for which I return my best thanks to Mr. Sclater the
Secretary, and to the Council.

Should my book meet with the approval of working naturalists, I venture to
appeal to them, to assist me in rendering any future editions more complete,
by sending me (to the care of my publishers) notes of any important

omissions, or corrections of any misstatements of fact; as well as copies of
any of their papers or essays, and especially of any lists, catalogues, and
monographs, containing information on the classification or distribution of
living or extinct animals.

To the many friends who have given me information or assistance I beg to
tender my sincere thanks. Especially am I indebted to Professor Newton,
who not only read through much of my rough MSS., but was so good as to
make numerous corrections and critical notes. These were of great value to
me, as they often contained or suggested important additional matter, or
pointed out systematic and orthographical inaccuracies.

Professor Flower was so good as to read over my chapters on extinct
animals, and to point out several errors into which I had fallen.

Dr. Günther gave me much valuable information on the classification of
reptiles, marking on my lists the best established and most natural genera,
and referring me to reliable sources of information.

I am also greatly indebted to the following gentlemen for detailed
information on special subjects:—

To Sir Victor Brooke, for a MS. arrangement of the genera of Bovidæ, with
the details of their distribution:

To Mr. Dresser, for lists of the characteristic birds of Northern and Arctic
Europe:

To Dr. Hooker, for information on the colours and odours of New Zealand
plants:

To Mr. Kirby, for a list of the butterflies of Chili:

To Professor Mivart, for a classification of the Batrachia, and an early proof
of his article on "Apes" in the Encyclopedia Britannica:

To Mr. Salvin, for correcting my list of the birds of the Galapagos, and for
other assistance:

To Mr. Sharpe, for MS. lists of the birds of Madagascar and the Cape Verd
Islands:

To Canon Tristram, for a detailed arrangement of the difficult family of the
warblers,—Sylviidæ:

To Viscount Walden, for notes on the systematic arrangement of the
Pycnonotidæ and Timaliidæ, and for an early proof of his list of the birds of
the Philippine Islands.

I also have to thank many naturalists, both in this country and abroad, who
have sent me copies of their papers; and I trust they will continue to favour
me in the same manner.

An author may easily be mistaken in estimating his own work. I am well
aware that this first outline of a great subject is, in parts, very meagre and
sketchy; and, though perhaps overburthened with some kinds of detail, yet
leaves many points most inadequately treated. It is therefore with some
hesitation that I venture to express the hope that I have made some
approach to the standard of excellence I have aimed at;—which was, that
my book should bear a similar relation to the eleventh and twelfth chapters
of the "Origin of Species," as Mr. Darwin's "Animals and Plants under
Domestication" does to the first chapter of that work. Should it be judged
worthy of such a rank, my long, and often wearisome labours, will be well
repaid.

March, 1876.

CONTENTS OF THE FIRST VOLUME.

PART I.

THE PRINCIPLES AND GENERAL
PHENOMENA OF DISTRIBUTION.

CHAPTER I.
INTRODUCTORY.

CHAPTER II.
THE MEANS OF DISPERSAL AND THE
MIGRATIONS OF ANIMALS.
10-34
Means of Dispersal of Mammalia (p.
10)—Climate as a Limit to the Range
of Mammals (p. 11)—Valleys and
Rivers as Barriers to Mammals (p.
12)—Arms of the Sea as Barriers to
Mammals (p. 13)—Ice-floes and
drift-wood as aiding the Dispersal of
Mammals (p. 14)—Means of
Dispersal of Birds (p. 15)—Dispersal
of Birds by Winds (p. 16)—Barriers
to the Dispersal of Birds (p. 17)—The
Phenomena of Migration (p. 18)—
Migrations of Birds (p. 19)—General
remarks on Migration (p. 25)—Means
of Dispersal of Reptiles and
Amphibia (p. 28)—Means of
Dispersal of Fishes (p. 29)—Means
of Dispersal of Mollusca (p. 30)—
Means of Dispersal of Insects and the

Barriers which limit their Range (p.
32)

CHAPTER III.
DISTRIBUTION AS AFFECTED BY THE
CONDITIONS AND CHANGES OF THE
EARTH'S SURFACE.

Land and Water (p. 35)—Continental
Areas (p. 36)—Recent Changes in the
Continental Areas (p. 38)—The
Glacial Epoch as affecting the
Distribution of Animals (p. 40)—
Changes of Vegetation as affecting
the Distribution of Animals (p. 43)—
Organic Changes as affecting
Distribution (p. 44) 35-49

CHAPTER IV.
ON ZOOLOGICAL REGIONS.
50-82
Principles upon which Zoological
Regions should be formed (p. 53)—
Which class of Animals is of most
importance in determining Zoological
Regions (p. 56)—Various Zoological
Regions proposed since 1857 (p. 58)
—Discussion of proposed Regions (p.
61)—Reasons for adopting the Six
Regions first proposed by Mr. Sclater
(p. 63)—Objections to the system of
Circumpolar Zones (p. 67)—Does the
Arctic Fauna characterise an
independent Region (p. 68)—
Palæarctic Region (p. 71)—Ethiopian
Region (p. 73)—Oriental Region (p.

75)—Australian Region (p. 77)—
Neotropical Region (p. 78)—Nearctic
Region (p. 79)—Observations on the
series of Sub-regions (p. 80)

CHAPTER V.
CLASSIFICATION AS AFFECTING THE
STUDY OF GEOGRAPHICAL DISTRIBUTION.

Classification of the Mammalia (p. 85)
—Classification of Birds (p. 92)—
Classification of Reptiles (p. 98)—
Classification of Amphibia (p. 100)—
Classification of Fishes (p. 101)—
Classification of Insects (p. 102)—
Classification of Mollusca (p. 104) 83-104

PART II.

ON THE DISTRIBUTION OF
EXTINCT ANIMALS.

CHAPTER VI.
THE EXTINCT MAMMALIA OF THE OLD
WORLD.
83-104
Historic and Post-pliocene Period (p.
110)—Pliocene Period (p. 112)—
General Conclusions as to the
Pliocene and Post-pliocene Faunas of
Europe (p. 113)—Miocene Period (p.
114)—Extinct Animals of Greece (p.
115)—Miocene Fauna of Central and
Western Europe (p. 117)—Upper
Miocene Deposits of India (p. 121)—

General Observations on the Miocene
Faunas of Europe and Asia (p. 123)—
Eocene Period (p. 124)—General
Considerations on the Extinct
Mammalian Fauna of Europe (p. 126)

CHAPTER VII.
EXTINCT MAMMALIA OF THE NEW WORLD.

North America—Post-pliocene Period
(p. 129)—Remarks on the Post-
pliocene Fauna of North America (p.
130)—Tertiary Period (p. 132)—
Primates (p. 132)—Insectivora (p.
133)—Carnivora (p. 134)—Ungulata
(p. 135)—Proboscidea (p. 138)—
Tillodontia (p. 139)—Rodentia (p.
140)—General Relations of the
Extinct Tertiary Mammalia of North
America and Europe (p. 140)—South
America (p. 143)—Fauna of the
Brazilian Caves (p. 143)—Pliocene
Period of Temperate South America
(p. 146)—Pliocene Mammalia of the
Antilles (p. 148)—Eocene Fauna of
South America (p. 148)—General
Remarks on the Extinct Mammalian
Fauna of the Old and New Worlds (p.
148)—The Birth-place and
Migrations of some Mammalian
Families and Genera (p. 153) 129-156

CHAPTER VIII.
VARIOUS EXTINCT ANIMALS;—AND ON
THE ANTIQUITY OF THE GENERA OF

INSECTS AND LAND-MOLLUSCA.

Extinct Mammalia of Australia (p. 157)
—Mammalian Remains of the
Secondary Formations (p. 159)—
Extinct Birds (p. 160)—Palæarctic
Region and North India (p. 161)—
North America (p. 163)—South
America, Madagascar, New Zealand
(p. 164)—Extinct Tertiary Reptiles (p.
165)—Antiquity of the Genera of
Insects (p. 166)—Antiquity of the
Genera of Land and Fresh-water
Shells (p. 168) 157-170

PART III.

ZOOLOGICAL GEOGRAPHY: A
REVIEW OF THE CHIEF FORMS
OF LIFE IN THE SEVERAL
REGIONS AND SUB-REGIONS,
WITH THE INDICATIONS THEY
AFFORD OF GEOGRAPHICAL
MUTATIONS.

CHAPTER IX.
THE ORDER OF SUCCESSION OF THE
REGIONS.—COSMOPOLITAN GROUPS OF
ANIMALS.—TABLES OF DISTRIBUTION.

Order of succession of the Regions (p.
173)—Cosmopolitan Groups (p. 175)
—Tables of Distributions of Families
and Genera (p. 177) 173-179

CHAPTER X.
THE PALÆARCTIC REGION.

Zoological Characteristics of the
Palæarctic Region (p. 181)—
Summary of Palæarctic Vertebrata (p.
186)—Insects (p. 187)—Land-shells
(p. 190)—The Palæarctic Sub-regions
(p. 190)—Central and Northern
Europe (p. 191)—North European
Islands (p. 197)—Mediterranean Sub-
region (p. 199)—The Mediterranean
and Atlantic Islands (p. 206)—The
Siberian Sub-region, or Northern Asia
(p. 216)—Japan and North China, or
the Manchurian Sub-region (p. 220)
—Birds (p. 223)—Insects (p. 227)—
Remarks on the General Character of
the Fauna of Japan (p. 230)—General
Conclusions as to the Fauna of the
Palæarctic Region (p. 231)—Table I.
Families of Animals inhabiting the
Palæarctic Region (p. 234)—Table II.
List of the Genera of Terrestrial
Mammalia and Birds of the
Palæarctic Region (p. 239) 181-250

CHAPTER XI.
THE ETHIOPIAN REGION.
251-313
Zoological Characteristics of the
Ethiopian Region (p. 252)—
Summary of Ethiopian Vertebrates (p.
255)—The Ethiopian Sub-regions (p.

258)—The East African Sub-region,
or Central and East Africa (p. 258)—
The West African Sub-region (p. 262)
—Islands of the West African Sub-
region (p. 265)—South African Sub-
region (p. 266)—Atlantic Islands of
the Ethiopian Region;—St. Helena (p.
269)—Tristan d'Acunha (p. 271)—
Madagascar and the Mascarene
Islands, or the Malagasy Sub-region
(p. 272)—The Mascarene Islands (p.
280)—Extinct Fauna of the
Mascarene Islands and Madagascar
(p. 282)—General Remarks on the
Insect Fauna of Madagascar (p. 284)
—On the probable Past History of the
Ethiopian Region (p. 285)—Table I.
Families of Animals inhabiting the
Ethiopian Region (p. 294)—Table II.
List of Genera of Terrestrial
Mammalia and Birds of the Ethiopian
Region (p. 300)

CHAPTER XII.
THE ORIENTAL REGION.
314-386
Zoological Characteristics of the
Oriental Region (p. 315)—Summary
of Oriental Vertebrata (p. 318)—The
Oriental Sub-regions (p. 321)—
Hindostan, or Indian Sub-region (p.
321)—Range of the Genera of
Mammalia which inhabit the Sub-
region of Hindostan (p. 322)—
Oriental, Palæarctic, and Ethiopian
Genera of Birds in Central India (p.

224)—Sub-region of Ceylon and
South India (p. 326)—The Past
History of Ceylon and South India, as
indicated by its Fauna (p. 328)—
Himalayan or Indo-Chinese Sub-
region (p. 329)—Islands of the Indo-
Chinese Sub-region (p. 333)—Indo-
Malaya, or the Malayan Sub-region
(p. 334)—Malayan Insects (p. 341)—
The Zoological Relations of the
several Islands of the Indo-Malay
Sub-region (p. 345)—Philippine
Islands (p. 345)—Java (p. 349)—
Malacca, Sumatra, and Borneo (p.
353)—Probable recent Geographical
Changes in the Indo-Malay Islands
(p. 357)—Probable Origin of the
Malayan Fauna (p. 359)—Concluding
Remarks on the Oriental Region (p.
362)—Table I. Families of Animals
inhabiting the Oriental Region (p.
365)—Table II. Genera of Terrestrial
Mammalia and Birds in the Oriental
Region (p. 371)

CHAPTER XIII.
THE AUSTRALIAN REGION.
387-485
General Zoological Characteristics of
the Australian Region (p. 390)—
Summary of the Australian Vertebrata
(p. 397)—Supposed Land-connection
between Australia and South America
(p. 398)—Insects (p. 403)—Land-
shells (p. 407)—Australian Sub-
regions (p. 408)—Austro-Malayan

Sub-region (p. 409)—Papua, or the
New Guinea Group (p. 409)—The
Moluccas (p. 417)—Insects—
Peculiarities of the Moluccan Fauna
(p. 420)—Timor Group (p. 422)—
Celebes Group (p. 426)—Origin of
the Fauna of Celebes (p. 436)—
Australia and Tasmania, or the
Australian Sub-region (p. 438)—The
Pacific Islands, or Polynesian Sub-
region (p. 442)—Fiji, Tonga, and
Samoa Islands (p. 443)—Society and
Marquesas Islands (p. 443)—Ladrone
and Caroline Islands (p. 444)—New
Caledonia and the New Hebrides (p.
444)—Sandwich Islands (p. 445)—
Reptiles of the Polynesian Sub-region
(p. 448)—New Zealand Sub-region
(p. 449)—Islets of the New Zealand
Sub-region (p. 453)—Reptiles,
Amphibia, and Fresh-water Fishes (p.
456)—Insects (p. 457)—The Ancient
Fauna of New Zealand (p. 459)—The
Origin of the New Zealand Fauna (p.
459)—Causes of the Poverty of
Insect-life in New Zealand: its
Influence on the Character of the
Flora (p. 462)—Concluding Remarks
on the Early History of the Australian
Region (p. 464)—Table I. Families of
Animals inhabiting the Australian
Region (p. 468)—Table II. Genera of
Terrestrial Mammalia and Birds of
the Australian Region (p. 473)

Index to Vol. I 489-503

MAPS AND ILLUSTRATIONS IN VOL. I.

1. Map of the World, showing the Zoo-Geographical
Regions and the
contour of the Ocean-bed Frontispiece

To face
page

2. Map of the Palæarctic Region 181

Plate I. The Alps of Central Europe with 195
3. Characteristic Animals

Plate II. Characteristic Mammalia of Western 218
4. Tartary

5. Plate III. Characteristic Animals of North China 226

6. Map of the Ethiopian Region 251

7. Plate IV. Characteristic Animals of East Africa 261

Plate V. Scene in West Africa with Characteristic 264
8. Animals

Plate VI. Scene in Madagascar with Characteristic 278
9. Animals

10. Map of the Oriental Region 315

Plate VII. Scene in Nepaul with Characteristic 331
11. Animals

Plate VIII. A Forest in Borneo with Characteristic 337
12. Mammalia

Plate IX. A Malacca Forest with some of its 340
13. Peculiar Birds

14. Map of the Australian Region 387

Plate X. Scene in New Guinea with Characteristic 415
15. Animals

Plate XI. The Characteristic Mammalia of 439
16. Tasmania

Plate XII. The Plains of New South Wales with 442
17. Characteristic Animals

Plate XIII. Scene in New Zealand with some of its 455
18. Remarkable Birds

ERRATA IN VOL. I.

I have detected several misprints and small errors in the final impression,
and Dr. Meyer, who has translated the work into German, has kindly
communicated all that he has noticed. It is not thought necessary to give
here all the smaller orthographical errors, most of which will be corrected in
the Index. The following seem, however, to be of sufficient importance to
justify me in asking my readers to correct them in their copies.

Page 93, 12 lines from foot, for Hocco read Hoazin.
" 97, line 2, for Hocco read Hoazin.
" 147, 13 lines from foot, for three-handed read three-banded.
" 177, line 6, for Lycænidæ read Zygænidæ.
" 183, line 20, for third read fourth.
" 238, line 18, for Spirigidea read Sphingidea.
" 242, insert | 92a | Tamias | 1 | All Northern Asia | N. America.

" 245, last line, insert in 2nd column (6).
" 309, line 20, for Motacilla read Budytes.
" 327, 12 lines from foot, after Hindostan read and.
" 331, last line, for Icthyopsis read Icthyophis.
" 340, line 15, for Edolius read Bhringa.
" 348, line 17, for Flores read New Guinea.
" 371, 11 lines from foot, for and Borneo read Borneo and
Philippines.
" 391, 10 lines from foot, after Celebes add and the Papuan Islands.
" 391, 9 lines from foot, omit New Guinea or.
" 414, 6 for Epimachus read Seleucides.
lines
from
foot,
" 415, for ditto read ditto.
line 10
" 427, line 20, after Celebes add and on some of the Philippine
Islands.
" 427, 5 lines from foot, for tusks read jaw.
" 462, 15 lines from foot, for p. 156 read p. 166.
" 474, 9 lines from foot, after Celebes add Papua.

THE

GEOGRAPHICAL DISTRIBUTION
OF ANIMALS.

PART I.
THE PRINCIPLES AND GENERAL PHENOMENA OF DISTRIBUTION.

CHAPTER I.

I N T R O D U C T O R Y.

It is a fact within the experience of most persons, that the various species of
animals are not uniformly dispersed over the surface of the country. If we
have a tolerable acquaintance with any district, be it a parish, a county, or a
larger extent of territory, we soon become aware that each well-marked
portion of it has some peculiarities in its animal productions. If we want to
find certain birds or certain insects, we have not only to choose the right
season but to go to the right place. If we travel beyond our district in
various directions we shall almost certainly meet with something new to us;
some species which we were accustomed to see almost daily will disappear,
others which we have never seen before will make their appearance. If we
go very far, so as to be able to measure our journey by degrees of latitude
and longitude and to perceive important changes of climate and vegetation,
the differences in the forms of animal life will become greater; till at length
we shall come to a country where almost everything will be new, all the
familiar creatures of our own district being replaced by others more or less
differing from them.

If we have been observant during our several journeys, and have combined
and compared the facts we have collected, it will become apparent that the
change we have witnessed has been of two distinct kinds. In our own and
immediately surrounding districts, particular species appeared and
disappeared because the soil, the aspect, or the vegetation, was adapted to
them or the reverse. The marshes, the heaths, the woods and forests, the
chalky downs, the rocky mountains, had each their peculiar inhabitants,
which reappeared again and again as we came to tracts of country suitable
for them. But as we got further away we began to find that localities very
similar to those we had left behind were inhabited by a somewhat different
set of species; and this difference increased with distance, notwithstanding
that almost identical external conditions might be often met with. The first
class of changes is that of stations; the second that of habitats. The one is a
local, the other a geographical phenomenon. The whole area over which a
particular animal is found may consist of any number of stations, but rarely
of more than one habitat. Stations, however, are often so extensive as to

include the entire range of many species. Such are the great seas and
oceans, the Siberian or the Amazonian forests, the North African deserts,
the Andean or the Himalayan highlands.

There is yet another difference in the nature of the change we have been
considering. The new animals which we meet with as we travel in any
direction from our starting point, are some of them very much like those we
have left behind us, and can be at once referred to familiar types; while
others are altogether unlike anything we have seen at home. When we reach
the Alps we find another kind of squirrel, in Southern Italy a distinct mole,
in Southern Europe fresh warblers and unfamiliar buntings. We meet also
with totally new forms; as the glutton and the snowy owl in Northern, the
genet and the hoopoe in Southern, and the saiga antelope and collared
pratincole in Eastern Europe. The first series are examples of what are
termed representative species, the second of distinct groups or types of
animals. The one represents a comparatively recent modification, and an
origin in or near the locality where it occurs; the other is a result of very
ancient changes both organic and inorganic, and is connected with some of
the most curious and difficult of the problems we shall have to discuss.

Having thus defined our subject, let us glance at the opinions that have
generally prevailed as to the nature and causes of the phenomena presented
by the geographical distribution of animals.

It was long thought, and is still a popular notion, that the manner in which
the various kinds of animals are dispersed over the globe is almost wholly
due to diversities of climate and of vegetation. There is indeed much to
favour this belief. The arctic regions are strongly characterised by their
white bears and foxes, their reindeer, ermine, and walruses, their white
ptarmigan, owls, and falcons; the temperate zone has its foxes and wolves,
its rabbits, sheep, beavers, and marmots, its sparrows and its song birds;
while tropical regions alone produce apes and elephants, parrots and
peacocks, and a thousand strange quadrupeds and brilliant birds which are
found nowhere in the cooler regions. So the camel, the gazelle and the
ostrich live in the desert; the bison on the prairie; the tapir, the deer, and the
jaguar in forests. Mountains and marshes, plains and rocky precipices, have

each their animal inhabitants; and it might well be thought, in the absence
of accurate inquiry, that these and other differences would sufficiently
explain why most of the regions and countries into which the earth is
popularly divided should have certain animals peculiar to them and should
want others which are elsewhere abundant.

A more detailed and accurate knowledge of the productions of different
portions of the earth soon showed that this explanation was quite
insufficient; for it was found that countries exceedingly similar in climate
and all physical features may yet have very distinct animal populations. The
equatorial parts of Africa and South America, for example, are very similar
in climate and are both covered with luxuriant forests, yet their animal life
is widely different; elephants, apes, leopards, guinea-fowls and touracos in
the one, are replaced by tapirs, prehensile-tailed monkeys, jaguars,
curassows and toucans in the other. Again, parts of South Africa and
Australia are wonderfully similar in their soil and climate; yet one has lions,
antelopes, zebras and giraffes; the other only kangaroos, wombats,
phalangers and mice. In like manner parts of North America and Europe are
very similar in all essentials of soil climate and vegetation, yet the former
has racoons, opossums, and humming-birds; while the latter possesses
moles, hedgehogs and true flycatchers. Equally striking are the facts
presented by the distribution of many large and important groups of
animals. Marsupials (opossums, phalangers &c.) are found from temperate
Van Diemen's land to the tropical islands of New Guinea and Celebes, and
in America from Chili to Virginia. No crows exist in South America, while
they inhabit every other part of the world, not excepting Australia.
Antelopes are found only in Africa and Asia; the sloths only in South
America; the true lemurs are confined to Madagascar, and the birds-of-
paradise to New Guinea.

If we examine more closely the distribution of animals in any extensive
region, we find that different, though closely allied species, are often found
on the opposite sides of any considerable barrier to their migration. Thus,
on the two sides of the Andes and Rocky Mountains in America, almost all
the mammalia, birds, and insects are of distinct species. To a less extent, the
Alps and Pyrenees form a similar barrier, and even great rivers and river
plains, as those of the Amazon and Ganges, separate more or less distinct

groups of animals. Arms of the sea are still more effective, if they are
permanent; a circumstance in some measure indicated by their depth. Thus
islands far away from land almost always have very peculiar animals found
nowhere else; as is strikingly the case in Madagascar and New Zealand, and
to a less degree in the West India islands. But shallow straits, like the
English Channel or the Straits of Malacca, are not found to have the same
effect, the animals being nearly or quite identical on their opposite shores. A
change of climate or a change of vegetation may form an equally effective
barrier to migration. Many tropical and polar animals are pretty accurately
limited by certain isothermal lines; and the limits of the great forests in
most parts of the world strictly determine the ranges of many species.

Naturalists have now arrived at the conclusion, that by some slow process
of development or transmutation, all animals have been produced from
those which preceded them; and the old notion that every species was
specially created as they now exist, at a particular time and in a particular
spot, is abandoned as opposed to many striking facts, and unsupported by
any evidence. This modification of animal forms took place very slowly, so
that the historical period of three or four thousand years has hardly
produced any perceptible change in a single species. Even the time since the
last glacial epoch, which on the very lowest estimate must be from 50,000
to 100,000 years, has only served to modify a few of the higher animals into
very slightly different species. The changes of the forms of animals appear
to have accompanied, and perhaps to have depended on, changes of
physical geography, of climate, or of vegetation; since it is evident that an
animal which is well adapted to one condition of things will require to be
slightly changed in constitution or habits, and therefore generally in form,
structure, or colour, in order to be equally well adapted to a changed
condition of surrounding circumstances. Animals multiply so rapidly, that
we may consider them as continually trying to extend their range; and thus
any new land raised above the sea by geological causes becomes
immediately peopled by a crowd of competing inhabitants, the strongest
and best adapted of which alone succeed in maintaining their position.

If we keep in view these facts—that the minor features of the earth's surface
are everywhere slowly changing; that the forms, and structure, and habits of
all living things are also slowly changing; while the great features of the

earth, the continents, and oceans, and loftiest mountain ranges, only change
after very long intervals and with extreme slowness; we must see that the
present distribution of animals upon the several parts of the earth's surface
is the final product of all these wonderful revolutions in organic and
inorganic nature. The greatest and most radical differences in the
productions of any part of the globe must be dependent on isolation by the
most effectual and most permanent barriers. That ocean which has remained
broadest and deepest from the most remote geological epoch will separate
countries the productions of which most widely and radically differ; while
the most recently-depressed seas, or the last-formed mountain ranges, will
separate countries the productions of which are almost or quite identical. It
will be evident, therefore, that the study of the distribution of animals and
plants may add greatly to our knowledge of the past history of our globe. It
may reveal to us, in a manner which no other evidence can, which are the
oldest and most permanent features of the earth's surface, and which the
newest. It may indicate the existence of islands or continents now sunk
beneath the ocean, and which have left no record of their existence save the
animal and vegetable productions which have migrated to adjacent lands. It
thus becomes an important adjunct to geology, which can rarely do more
than determine what lands have been raised above the waters, under what
conditions and at what period; but can seldom ascertain anything of the
position or extent of those which have sunk beneath it. Our present study
may often enable us, not only to say where lands must have recently
disappeared, but also to form some judgment as to their extent, and the time
that has elapsed since their submersion.

Having thus briefly sketched the nature and objects of the subject we have
to study, it will be necessary—before entering on a detailed examination of
the zoological features of the different parts of the earth, and of the
distribution of the orders, families, and genera of animals—to examine
certain preliminary facts and principles essential for our guidance. We must
first inquire what are the powers of multiplication and dispersal of the
various groups of animals, and the nature of the barriers that most
effectually limit their range. We have then to consider the effects of changes
in physical geography and in climate; to examine the nature and extent of

such changes as have been known to occur; to determine what others are
possible or probable; and to ascertain the various modes in which such
changes affect the structure, the distribution, or the very existence of
animals.

Two subjects of a different nature must next engage our attention. We have
to deal with two vast masses of facts, each involving countless details, and
requiring subdivision and grouping to be capable of intelligible treatment.
All the continents and their chief subdivisions, and all the more important
islands of the globe, have to be compared as regards their various animal
forms. To do this effectively we require a natural division of the earth
especially adapted to our purpose; and we shall have to discuss at some
length the reasons for the particular system adopted,—a discussion which
must to some extent anticipate and summarize the conclusions of the whole
work. We have also to deal with many hundreds of families and many
thousands of genera of animals, and here too a true and natural
classification is of great importance. We must therefore give a connected
view of the classification adopted in the various classes of animals dealt
with.

And lastly, as the existing distribution of animals is the result and outcome
of all preceding changes of the earth and of its inhabitants, we require as
much knowledge as we can get of the animals of each country during past
geological epochs, in order to interpret the facts we shall accumulate. We
shall, therefore, enter upon a somewhat detailed sketch of the various forms
of extinct animals that have lived upon the earth during the Tertiary period;
discuss their migrations at various epochs, the changes of physical
geography that they imply, and the extent to which they enable us to
determine the birthplace of certain families and genera.

The preliminary studies above enumerated will, it is believed, enable us to
see the bearing of many facts in the distribution of animals that would
otherwise be insoluble problems; and, what is hardly less valuable, will
teach us to estimate the comparative importance of the various groups of
animals, and to avoid the common error of cutting the gordian knot of each

difficulty by vast hypothetical changes in existing continents and oceans—
probably the most permanent features of our globe.

CHAPTER II.

T H E M E A N S O F D I S P E R S A L A N D T H E M I G R AT I O N S O F
ANIMALS.

All animals are capable of multiplying so rapidly, that if a single pair were
placed in a continent with abundance of food and no enemies, they might
fully stock it in a very short time. Thus, a bird which produces ten pairs of
young during its lifetime (and this is far below the fertility of many birds)
will, if we take its life at five years, increase to a hundred millions in about
forty years, a number sufficient to stock a large country. Many fishes and
insects are capable of multiplying several thousandfold each year, so that in
a few years they would reach billions and trillions. Even large and slow
breeding mammals, which have only one at a birth but continue to breed
from eight to ten successive years, may increase from a single pair to ten
millions in less than forty years.

But as animals rarely have an unoccupied country to breed in, and as the
food in any one district is strictly limited, their natural tendency is to roam
in every direction in search of fresh pastures, or new hunting grounds. In
doing so, however, they meet with many obstacles. Rocks and mountains
have to be climbed, rivers or marshes to be crossed, deserts or forests to be
traversed; while narrow straits or wider arms of the sea separate islands
from the main land or continents from each other. We have now to inquire
what facilities the different classes of animals have for overcoming these
obstacles, and what kind of barriers are most effectual in checking their
progress.

Means of Dispersal of Mammalia.—Many of the largest mammalia are able
to roam over whole continents and are hardly stopped by any physical
obstacles. The elephant is almost equally at home on plains and mountains,
and it even climbs to the highest summit of Adam's Peak in Ceylon, which
is so steep and rocky as to be very difficult of ascent for man. It traverses
rivers with great ease and forces its way through the densest jungle. There
seems therefore to be no limit to its powers of wandering, but the necessity
of procuring food and its capacity of enduring changes of climate. The tiger

is another animal with great powers of dispersal. It crosses rivers and
sometimes even swims over narrow straits of the sea, and it can endure the
severe cold of North China and Tartary as well as the heats of the plains of
Bengal. The rhinoceros, the lion, and many of the ruminants have equal
powers of dispersal; so that wherever there is land and sufficient food, there
are no limits to their possible range. Other groups of animals are more
limited in their migrations. The apes, lemurs, and many monkeys are so
strictly adapted to an arboreal life that they can never roam far beyond the
limits of the forest vegetation. The same may be said of the squirrels, the
opossums, the arboreal cats, and the sloths, with many other groups of less
importance. Deserts or open country are equally essential to the existence of
others. The camel, the hare, the zebra, the giraffe and many of the antelopes
could not exist in a forest country any more than could the jerboas or the
prairie marmots.

There are other animals which are confined to mountains, and could not
extend their range into lowlands or forests. The goats and the sheep are the
most striking group of this kind, inhabiting many of the highest mountains
of the globe; of which the European ibex and mouflon are striking
examples. Rivers are equally necessary to the existence of others, as the
beaver, otter, water-vole and capybara; and to such animals high mountain-
ranges or deserts must form an absolutely impassable barrier.

Climate as a Limit to the Range of Mammals.—Climate appears to limit the
range of many animals, though there is some reason to believe that in many
cases it is not the climate itself so much as the change of vegetation
consequent on climate which produces the effect. The quadrumana appear
to be limited by climate, since they inhabit almost all the tropical regions
but do not range more than about 10° beyond the southern and 12° beyond
the northern tropic, while the great bulk of the species are found only within
an equatorial belt about 30° wide. But as these animals are almost
exclusively fruit-eaters, their distribution depends as much on vegetation as
on temperature; and this is strikingly shown by the fact that the
Semnopithecus schistaceus inhabits the Himalayan mountains to a height of
11,000 feet, where it has been seen leaping among fir-trees loaded with
snow-wreaths! Some northern animals are bounded by the isothermal of

32°. Such are the polar bear and the walrus, which cannot live in a state of
nature far beyond the limits of the frozen ocean; but as they live in
confinement in temperate countries, their range is probably limited by other
conditions than temperature.

We must not therefore be too hasty in concluding, that animals which we
now see confined to a very hot or a very cold climate are incapable of living
in any other. The tiger was once considered a purely tropical animal, but it
inhabits permanently the cold plains of Manchuria and the Amoor, a
country of an almost arctic winter climate. Few animals seem to us more
truly inhabitants of hot countries than the elephants and rhinoceroses; yet in
Post-tertiary times they roamed over the whole of the northern continents to
within the arctic circle; and we know that the climate was then as cold as it
is now, from their entire bodies being preserved in ice. Some change must
recently have occurred either in the climate, soil, or vegetation of Northern
Asia which led to the extinction of these forerunners of existing tropical
species; and we must always bear in mind that similar changes may have
acted upon other species which we now find restricted within narrow limits,
but which may once have roamed over a wide and varied territory.

Valleys and Rivers as Barriers to Mammals.—To animals which thrive best
in dry and hilly regions, a broad level and marshy valley must often prove
an effectual barrier. The difference of vegetation and of insect life, together
with an unhealthy atmosphere, no doubt often checks migration if it is
attempted. Thus many animals are restricted to the slopes of the Himalayas
or to the mountains of Central India, the flat valley of the Ganges forming a
limit to their range. In other cases, however, it is the river rather than the
valley which is the barrier. In the great Amazonian plains many species of
monkeys, birds, and even insects are found up to the river banks on one side
but do not cross to the other. Thus in the lower part of the Rio Negro two
monkeys, the Jacchus bicolor and the Brachiurus couxiou, are found on the
north bank of the river but never on the south, where a red-whiskered
Pithecia is alone found. Higher up Ateles paniscus extends to the north
bank of the river while Lagothrix humboldtii comes down to the south
bank; the former being a native of Guiana, the latter of Ecuador. The range
of the birds of the genus Psophia or trumpeters, is also limited by the rivers

Amazon, Madeira, Rio Negro and some others; so that in these cases we are
able to define the limits of distribution with an unusual degree of accuracy,
and there is little doubt the same barriers also limit a large number of other
species.

Arms of the Sea as Barriers to Mammals.—Very few mammals can swim
over any considerable extent of sea, although many can swim well for short
distances. The jaguar traverses the widest streams in South America, and
the bear and bison cross the Mississippi; and there can be no doubt that they
could swim over equal widths of salt water, and if accidentally carried out
to sea might sometimes succeed in reaching islands many miles distant.
Contrary to the common notion pigs can swim remarkably well. Sir Charles
Lyell tells us in his "Principles of Geology" that during the floods in
Scotland in 1829, some pigs only six months old that were carried out to
sea, swam five miles and got on shore again. He also states, on the authority
of the late Edward Forbes, that a pig jumped overboard to escape from a
terrier in the Grecian Archipelago, and swam safely to shore many miles
distant. These facts render it probable that wild pigs, from their greater
strength and activity, might under favourable circumstances cross arms of
the sea twenty or thirty miles wide; and there are facts in the distribution of
this tribe of animals which seem to indicate that they have sometimes done
so. Deer take boldly to the water and can swim considerable distances, but
we have no evidence to show how long they could live at sea or how many
miles they could traverse. Squirrels, rats, and lemmings often migrate from
northern countries in bands of thousands and hundreds of thousands, and
pass over rivers, lakes and even arms of the sea, but they generally perish in
the saltwater. Admitting, however, the powers of most mammals to swim
considerable distances, we have no reason to believe that any of them could
traverse without help straits of upwards of twenty miles in width, while in
most cases a channel of half that distance would prove an effectual barrier.

Ice-floes and Driftwood as Aiding the Dispersal of Mammals.—In the arctic
regions icebergs originate in glaciers which descend into the sea, and often
bear masses of gravel, earth, and even some vegetation on their surfaces;
and extensive level ice-fields break away and float southwards. These might

often carry with them such arctic quadrupeds as frequent the ice, or even on
rare occasions true land-animals, which might sometimes be stranded on
distant continents or islands. But a more effectual because a more wide-
spread agent, is to be found in the uprooted trees and rafts of driftwood
often floated down great rivers and carried out to sea. Such rafts or islands
are sometimes seen drifting a hundred miles from the mouth of the Ganges
with living trees erect upon them; and the Amazon, the Orinoco,
Mississippi, Congo, and most great rivers produce similar rafts. Spix and
Martius declare that they saw at different times on the Amazon, monkeys,
tiger-cats, and squirrels, being thus carried down the stream. On the Parana,
pumas, squirrels, and many other quadrupeds have been seen on these rafts;
and Admiral W. H. Smyth informed Sir C. Lyell that among the Philippine
islands after a hurricane, he met with floating masses of wood with trees
growing upon them, so that they were at first mistaken for islands till it was
found that they were rapidly drifting along. Here therefore, we have ample
means for carrying all the smaller and especially the arboreal mammals out
to sea; and although in most cases they would perish there, yet in some
favourable instances strong winds or unusual tidal currents might carry
them safely to shores perhaps several hundred miles from their native
country. The fact of green trees so often having been seen erect on these
rafts is most important; for they would act as a sail by which the raft might
he propelled in one direction for several days in succession, and thus at last
reach a shore to which a current alone would never have carried it.

There are two groups of mammals which have quite exceptional means of
dispersal—the bats which fly, and the cetacea, seals, &c., which swim. The
former are capable of traversing considerable spaces of sea, since two North
American species either regularly or occasionally visit the Bermudas, a
distance of 600 miles from the mainland. The oceanic mammals (whales
and porpoises) seem to have no barrier but temperature; the polar species
being unable to cross the equator, while the tropical forms are equally
unfitted for the cold polar waters. The shore-feeding manatees, however,
can only live where they find food; and a long expanse of rocky coast
would probably be as complete a barrier to them as a few hundred miles of
open ocean. The amphibious seals and walruses seem many of them to be
capable of making long sea journeys, some of the species being found on

islands a thousand miles apart, but none of the arctic are identical with the
antartic species.

The otters with one exception are freshwater animals, and we have no
reason to believe they could or would traverse any great distances of salt
water. In fact, they would be less liable to dispersal across arms of the sea
than purely terrestrial species, since their powers of swimming would
enable them to regain the shore if accidentally carried out to sea by a
sudden flood.

Means of Dispersal of Birds.—It would seem at first sight that no barriers
could limit the range of birds, and that they ought to be the most ubiquitous
of living things, and little fitted therefore to throw any light on the laws or
causes of the geographical distribution of animals. This, however, is far
from being the case; many groups of birds are almost as strictly limited by
barriers as the mammalia; and from their larger numbers and the avidity
with which they have been collected, they furnish materials of the greatest
value for our present study. The different groups of birds offer remarkable
contrasts in the extent of their range, some being the most cosmopolite of
the higher animals, while others are absolutely confined to single spots on
the earth's surface. The petrels (Procellariidæ) and the gulls (Laridæ) are
among the greatest wanderers; but most of the species are confined to one
or other of the great oceans, or to the arctic or antarctic seas, a few only
being found with scarcely any variation over almost the whole globe. The
sandpipers and plovers wander along the shores as far as do the petrels over
the ocean. Great numbers of them breed in the arctic regions and migrate as
far as India and Australia, or down to Chili and Brazil; the species of the old
and new worlds, however, being generally distinct. In striking contrast to
these wide ranges we find many of the smaller perching birds, with some of
the parrots and pigeons, confined to small islands of a few square miles in
extent, or to single valleys or mountains on the mainland.

Dispersal of Birds by Winds.—Those groups of birds which possess no
powers of flight, such as the ostrich, cassowary, and apteryx, are in exactly
the same position as mammalia as regards their means of dispersal, or are
perhaps even inferior to them; since, although they are able to cross rivers

by swimming, it is doubtful if they could remain so long in the water as
most land quadrupeds. A very large number of short-winged birds, such as
toucans, pittas, and wrens, are perhaps worse off; for they can fly very few
miles at a time, and on falling into the water would soon be drowned. It is
only the strong-flying species that can venture to cross any great width of
sea; and even these rarely do so unless compelled by necessity to migrate in
search of food, or to a more genial climate. Small and weak birds are,
however, often carried accidentally across great widths of ocean by violent
gales. This is well exemplified by the large numbers of stragglers from
North America, which annually reach the Bermudas. No less than sixty-nine
species of American birds have occurred in Europe, most of them in Britain
and Heligoland. They consist chiefly of migratory birds which in autumn
return along the eastern coasts of the United States, and often fly from point
to point across bays and inlets. They are then liable to be blown out to sea
by storms, which are prevalent at this season; and it is almost always at this
time of year that their occurrence has been noted on the shores of Europe. It
may, however, be doubted whether this is not an altogether modern
phenomenon, dependent on the number of vessels constantly on the Atlantic
which afford resting-places to the wanderers; as it is hardly conceivable that
such birds as titlarks, cuckoos, wrens, warblers, and rails, could remain on
the wing without food or rest, the time requisite to pass over 2,000 miles of
ocean. It is somewhat remarkable that no European birds reach the
American coast but a few which pass by way of Iceland and Greenland;
whereas a considerable number do reach the Azores, fully half way across;
so that their absence can hardly be due to the prevailing winds being
westerly. The case of the Azores is, however, an argument for the unassisted
passage of birds for that distance; since two of the finches are peculiar
'species,' but closely allied to European forms, so that their progenitors
must, probably, have reached the islands before the Atlantic was a
commercial highway.

Barriers to the Dispersal of Birds.—We have seen that, as a rule, wide
oceans are an almost absolute barrier to the passage of most birds from one
continent to another; but much narrower seas and straits are also very
effectual barriers where the habits of the birds are such as to preserve them
from being carried away by storms. All birds which frequent thickets and
forests, and which feed near or on the ground, are secure from such

accidents; and they are also restricted in their range by the extent of the
forests they inhabit. In South America a large number of the birds have their
ranges determined by the extent of the forest country, while others are
equally limited to the open plains. Such species are also bounded by
mountain ranges whenever these rise above the woody region. Great rivers,
such as the Amazon, also limit the range of many birds, even when there
would seem to be no difficulty in their crossing them. The supply of food,
and the kind of vegetation, soil, and climate best suited to a bird's habits, are
probably the causes which mark out the exact limits of the range of each
species; to which must be added the prevalence of enemies of either the
parent birds, the eggs, or the young. In the Malay Archipelago pigeons
abound most where monkeys do not occur; and in South America the same
birds are comparatively scarce in the forest plains where monkeys are very
abundant, while they are plentiful on the open plains and campos, and on
the mountain plateaux, where these nest-hunting quadrupeds are rarely
found. Some birds are confined to swamps, others to mountains; some can
only live on rocky streams, others on deserts or grassy plains.

The Phenomena of Migration.—The term "migration" is often applied to
the periodical or irregular movements of all animals; but it may be
questioned whether there are any regular migrants but birds and fishes. The
annual or periodical movements of mammalia are of a different class.
Monkeys ascend the Himalayas in summer to a height of 10,000 to 12,000
feet, and descend again in winter. Wolves everywhere descend from the
mountains to the lowlands in severe weather. In dry seasons great herds of
antelopes move southwards towards the Cape of Good Hope. The well-
known lemmings, in severe winters, at long intervals, move down from the
mountains of Scandinavia in immense numbers, crossing lakes and rivers,
eating their way through haystacks, and surmounting every obstacle till they
reach the sea, whence very few return. The alpine hare, the arctic fox, and
many other animals, exhibit similar phenomena on a smaller scale; and
generally it may be said, that whenever a favourable succession of seasons
has led to a great multiplication of any species, it must on the pressure of
hunger seek food in fresh localities. For such movements as these we have
no special term. The summer and winter movements best correspond to true
migration, but they are always on a small scale, and of limited extent; the
other movements are rather temporary incursions than true migrations.

The annual movements of many fishes are more strictly analogous to the
migration of birds, since they take place in large bodies and often to
considerable distances, and are immediately connected with the process of
reproduction. Some, as the salmon, enter rivers; others, as the herring and
mackerel, approach the coast in the breeding season; but the exact course of
their migrations is unknown, and owing to our complete ignorance of the
area each species occupies in the ocean, and the absence of such barriers
and of such physical diversities as occur on the land, they are of far less
interest and less connected with our present study than the movements of
birds, to which we shall now confine ourselves.

Migrations of Birds.—In all the temperate parts of the globe there are a
considerable number of birds which reside only a part of the year, regularly
arriving and leaving at tolerably fixed epochs. In our own country many
northern birds visit us in winter, such as the fieldfare, redwing, snow-
bunting, turnstone, and numerous ducks and waders; with a few, like the
black redstart, and (according to Rev. C. A. Johns) some of the woodcocks
from the south. In the summer a host of birds appear—the cuckoo, the
swifts and swallows, and numerous warblers, being the most familiar,—
which stay to build their nests and rear their young, and then leave us again.
These are true migrants; but a number of other birds visit us occasionally,
like the waxwing, the oriole, and the beefeater, and can only be classed as
stragglers, which, perhaps from too rapid multiplication one year and want
of food the next, are driven to extend their ordinary range of migration to an
unusual degree. We will now endeavour to sketch the chief phenomena of
migration in different countries.

Europe.—It is well ascertained that most of the birds that spend their spring
and summer in the temperate parts of Europe pass the winter in North
Africa and Western Asia. The winter visitants, on the other hand, pass the
summer in the extreme north of Europe and Asia, many of them having
been found to breed in Lapland. The arrival of migratory birds from the
south is very constant as to date, seldom varying more than a week or two,
without any regard to the weather at the time; but the departure is less
constant, and more dependent on the weather. Thus the swallow always
comes to us about the middle of April, however cold it may be, while its
departure may take place from the end of September to late in October, and

is said by Forster to occur on the first N. or N.E. wind after the 20th of
September.

Almost all the migratory birds of Europe go southward to the
Mediterranean, move along its coasts east or west, and cross over in three
places only; either from the south of Spain, in the neighbourhood of
Gibraltar, from Sicily over Malta, or to the east by Greece and Cyprus.
They are thus always in sight of land. The passage of most small birds (and
many of the larger ones too) takes place at night; and they only cross the
Mediterranean when the wind is steady from near the east or west, and
when there is moonlight.

It is a curious fact, but one that seems to be well authenticated, that the
males often leave before the females, and both before the young birds,
which in considerable numbers migrate later and alone. These latter,
however, seldom go so far as the old ones; and numbers of young birds do
not cross the Mediterranean, but stay in the south of Europe. The same rule
applies to the northward migration; the young birds stopping short of the
extreme arctic regions, to which the old birds migrate.[1] When old and
young go together, however, the old birds take the lead. In the south of
Europe few of the migratory birds stay to breed, but pass on to more
temperate zones; thus, in the south of France, out of 350 species only 60
breed there. The same species is often sedentary in one part of Europe and
migratory in another; thus, the chaffinch is a constant resident in England,
Germany, and the middle of France; but a migrant in the south of France
and in Holland: the rook visits the south of France in winter only: the Falco
tinnunculus is both a resident and a migrant in the south of France,
according to M. Marcel de Serres, there being two regular passages every
year, while a certain number always remain.

We see, then, that migration is governed by certain intelligible laws; and
that it varies in many of its details, even in the same species, according to
changed conditions. It may be looked upon as an exaggeration of a habit
common to all locomotive animals, of moving about in search of food. This
habit is greatly restricted in quadrupeds by their inability to cross the sea or
even to pass through the highly-cultivated valleys of such countries as

Europe; but the power of flight in birds enables them to cross every kind of
country, and even moderate widths of sea; and as they mostly travel at night
and high in the air, their movements are difficult to observe, and are
supposed to be more mysterious than they perhaps are. In the tropics birds
move about to different districts according as certain fruits become ripe,
certain insects abundant, or as flooded tracts dry up. On the borders of the
tropics and the temperate zone extends a belt of country of a more or less
arid character, and liable to be parched at the summer solstice. In winter and
early spring its northern margin is verdant, but it soon becomes burnt up,
and most of its birds necessarily migrate to the more fertile regions to the
north of them. They thus follow the spring or summer as it advances from
the south towards the pole, feeding on the young flower buds, the
abundance of juicy larvæ, and on the ripening fruits; and as soon as these
become scarce they retrace their steps homewards to pass the winter. Others
whose home is nearer the pole are driven south by cold, hunger, and
darkness, to more hospitable climes, returning northward in the early
summer. As a typical example of a migratory bird, let us take the
nightingale. During the winter this bird inhabits almost all North Africa,
Asia Minor, and the Jordan Valley. Early in April it passes into Europe by
the three routes already mentioned, and spreads over France, Britain,
Denmark, and the south of Sweden, which it reaches by the beginning of
May. It does not enter Brittany, the Channel Islands, or the western part of
England, never visiting Wales, except the extreme south of Glamorganshire,
and rarely extending farther north than Yorkshire. It spreads over Central
Europe, through Austria and Hungary to Southern Russia and the warmer
parts of Siberia, but it nevertheless breeds in the Jordan Valley, so that in
some places it is only the surplus population that migrates. In August and
September, all who can return to their winter quarters.

Migrations of this type probably date back from at least the period when
there was continuous land along the route passed over; and it is a suggestive
fact that this land connection is known to have existed in recent geological
times. Britain was connected with the Continent during, and probably
before, the glacial epoch; and Gibraltar, as well as Sicily and Malta, were
also recently united with Africa, as is proved by the fossil elephants and
other large mammalia found in their caverns, by the comparatively shallow
water still existing in this part of the Mediterranean while the remainder is

of oceanic profundity, and by the large amount of identity in the species of
land animals still inhabiting the opposite shores of the Mediterranean. The
submersion of these two tracts of land (which were perhaps of considerable
extent) would be a slow process, and from year to year the change might be
hardly perceptible. It is easy to see how the migration that had once taken
place over continuous land would be kept up, first over lagoons and
marshes, then over a narrow channel, and subsequently over a considerable
sea, no one generation of birds ever perceiving any difference in the route.

There is, however, no doubt that the sea-passage is now very dangerous to
many birds. Quails cross in immense flocks, and great numbers are
drowned at sea whenever the weather is unfavourable. Some individuals
always stay through the winter in the south of Europe, and a few even in
England and Ireland; and were the sea to become a little wider the
migration would cease, and the quail, like some other birds, would remain
divided between south Europe and north Africa. Aquatic birds are observed
to follow the routes of great rivers and lakes, and the shores of the sea. One
great body reaches central Europe by way of the Danube from the shores of
the Black Sea; another ascends the Rhone Valley from the Gulf of Lyons.

India and China.—In the peninsula of India and in China great numbers of
northern birds arrive during September and October, and leave from March
to May. Among the smaller birds are wagtails, pipits, larks, stonechats,
warblers, thrushes, buntings, shrikes, starlings, hoopoes, and quails. Some
species of cranes and storks, many ducks, and great numbers of
Scolopacidæ also visit India in winter; and to prey upon these come a band
of rapacious birds—the peregrine falcon, the hobby, kestrel, common
sparrowhawk, harrier, and the short-eared owl. These birds are almost all
natives of Europe and Western Asia; they spread over all northern and
central India, mingling with the sedentary birds of the oriental fauna, and
give to the ornithology of Hindostan at this season quite a European aspect.
The peculiar species of the higher Himalayas do not as a rule descend to the
plains in winter, but merely come lower down the mountains; and in
southern India and Ceylon comparatively few of these migratory birds
appear.

In China the migratory birds follow generally the coast line, coming
southwards in winter from eastern Siberia and northern Japan; while a few
purely tropical forms travel northwards in summer to Japan, and on the
mainland as far as the valley of the Amoor.

North America.—The migrations of birds in North America have been
carefully studied by resident naturalists, and present some interesting
features. The birds of the eastern parts of North America are pre-eminently
migratory, a much smaller proportion being permanent residents than in
corresponding latitudes in Europe. Thus, in Massachusetts there are only
about 30 species of birds which are resident all the year, while the regular
summer visitors are 106. Comparing with this our own country, though
considerably further north, the proportions are reversed; there being 140
residents and 63 summer visitors. This difference is clearly due to the much
greater length and severity of the winter, and the greater heat of summer, in
America than with us. The number of permanent residents increases pretty
regularly as we go southward; but the number of birds at any locality during
the breeding season seems to increase as we go northward as far as Canada,
where, according to Mr. Allen, more species breed than in the warm
Southern States. Even in the extreme north, beyond the limit of forests,
there are no less than 60 species which breed; in Canada about 160; while
in Carolina there are only 135, and in Louisiana, 130. The extent of the
migration varies greatly, some species only going a few degrees north and
south, while others migrate annually from the tropics to the extreme north
of the continent; and every gradation occurs between these extremes.
Among those which migrate furthest are the species of Dendrœca, and other
American flycatching warblers (Mniotiltidæ), many of which breed on the
shores of Hudson's Bay, and spend the winter in Mexico or the West Indian
islands.

The great migratory movement of American birds is almost wholly
confined to the east coast; the birds of the high central plains and of
California being for the most part sedentary, or only migrating for short
distances. All the species which reach South America, and most of those
which winter in Mexico and Guatemala, are exclusively eastern species;
though a few Rocky Mountain birds range southward along the plateaux of
Mexico and Guatemala, but probably not as regular annual migrants.

In America as in Europe birds appear in spring with great regularity, while
the time of the autumnal return is less constant. More curious is the fact,
also observed in both hemispheres, that they do not all return by the same
route followed in going northwards, some species being constant visitors to
certain localities in spring but not in autumn, others in autumn but not in
spring.

Some interesting cases have been observed in America of a gradual
alteration in the extent of the migration of certain birds. A Mexican swallow
(Hirundo lunifrons) first appeared in Ohio in 1815. Year by year it increased
the extent of its range till by 1845 it had reached Maine and Canada; and it
is now quoted by American writers as extending its annual migrations to
Hudson's Bay. An American wren (Troglodytes ludovicianus) is another bird
which has spread considerably northwards since the time of the
ornithologist Wilson; and the rice-bird, or "Bob-o'-link," of the Americans,
continually widens its range as rice and wheat are more extensively
cultivated. This bird winters in Cuba and other West Indian Islands, and
probably also in Mexico. In April it enters the Southern States and passes
northward, till in June it reaches Canada and extends west to the
Saskatchewan River in 54° north latitude.

South Temperate America.—The migratory birds of this part of the world
have been observed by Mr. Hudson at Buenos Ayres. As in Europe and
North America, there are winter and summer visitors, from Patagonia and
the tropics respectively. Species of Pyrocephalus, Milvulus, swallows, and a
hummingbird, are among the most regular of the summer visitors. They are
all insectivorous birds. From Patagonia species of Tænioptera, Cinclodes,
and Centrites, come in winter, with two gulls, two geese, and six snipes and
plovers. Five species of swallows appear at Buenos Ayres in spring, some
staying to breed, others passing on to more temperate regions farther south.
As a rule the birds which come late and leave early are the most regular.
Some are very irregular in their movements, the Molothrus bonariensis, for
example, sometimes leaves early in autumn, sometimes remains all the
winter. Some resident birds also move in winter to districts where they are
never seen in summer.

General Remarks on Migration.—The preceding summary of the main facts
of migration (which might have been almost indefinitely extended, owing to
the great mass of detailed information that exists on the subject) appears to
accord with the view already suggested, that the "instinct" of migration has
arisen from the habit of wandering in search of food common to all animals,
but greatly exaggerated in the case of birds by their powers of flight and by
the necessity for procuring a large amount of soft insect food for their
unfledged young. Migration in its simple form may be best studied in North
America, where it takes place over a continuous land surface with a
considerable change of climate from south to north. We have here (as
probably in Europe and elsewhere) every grade of migration, from species
which merely shift the northern and southern limits of their range a few
hundred miles, so that in the central parts of the area the species is a
permanent resident, to others which move completely over 1,000 miles of
latitude, so that in all the intervening districts they are only known as birds
of passage. Now, just as the rice-bird and the Mexican swallow have
extended their migrations, owing to favourable conditions induced by
human agency; so we may presume that large numbers of species would
extend their range where favourable conditions arose through natural
causes. If we go back only as far as the height of the glacial epoch, there is
reason to believe that all North America, as far south as about 40° north
latitude, was covered with an almost continuous and perennial ice-sheet. At
this time the migratory birds would extend up to this barrier (which would
probably terminate in the midst of luxuriant vegetation, just as the glaciers
of Switzerland now often terminate amid forests and corn-fields), and as the
cold decreased and the ice retired almost imperceptibly year by year, would
follow it up farther and farther according as the peculiarities of vegetation
and insect-food were more or less suited to their several constitutions. It is
an ascertained fact that many individual birds return year after year to build
their nests in the same spot. This shows a strong local attachment, and is, in
fact, the faculty or feeling on which their very existence probably depends.
For were they to wander at random each year, they would almost certainly
not meet with places so well suited to them, and might even get into
districts where they or their young would inevitably perish. It is also a
curious fact that in so many cases the old birds migrate first, leaving the
young ones behind, who follow some short time later, but do not go so far
as their parents. This is very strongly opposed to the notion of an imperative

instinct. The old birds have been before, the young have not; and it is only
when the old ones have all or nearly all gone that the young go too,
probably following some of the latest stragglers. They wander, however,
almost at random, and the majority are destroyed before the next spring.
This is proved by the fact that the birds which return in spring are as a rule
not more numerous than those which came the preceding spring, whereas
those which went away in autumn were two or three times as numerous.
Those young birds that do get back, however, have learnt by experience,
and the next year they take care to go with the old ones. The most striking
fact in favour of the "instinct" of migration is the "agitation," or excitement,
of confined birds at the time when their wild companions are migrating. It
seems probable, however, that this is what may be called a social
excitement, due to the anxious cries of the migrating birds; a view
supported by the fact stated by Marcel de Serres, that the black swan of
Australia, when domesticated in Europe, sometimes joins wild swans in
their northward migration. We must remember too that migration at the
proper time is in many cases absolutely essential to the existence of the
species; and it is therefore not improbable that some strong social emotion
should have been gradually developed in the race, by the circumstance that
all who for want of such emotion did not join their fellows inevitably
perished.

The mode by which a passage originally overland has been converted into
one over the sea offers no insuperable difficulties, as has already been
pointed out. The long flights of some birds without apparently stopping on
the way is thought to be inexplicable, as well as their finding their nesting-
place of the previous year from a distance of many hundreds or even a
thousand miles. But the observant powers of animals are very great; and
birds flying high in the air may be guided by the physical features of the
country spread out beneath them in a way that would be impracticable to
purely terrestrial animals.

It is assumed by some writers that the breeding-place of a species is to be
considered as its true home rather than that to which it retires in winter; but
this can hardly be accepted as a rule of universal application. A bird can
only breed successfully where it can find sufficient food for its young; and
the reason probably why so many of the smaller birds leave the warm

southern regions to breed in temperate or even cold latitudes, is because
caterpillars and other soft insect larvæ are there abundant at the proper time,
while in their winter home the larvæ have all changed into winged insects.
But this favourable breeding district will change its position with change of
climate; and as the last great change has been one of increased warmth in
all the temperate zones, it is probable that many of the migratory birds are
comparatively recent visitors. Other changes may however have taken
place, affecting the vegetation and consequently the insects of a district; and
we have seldom the means of determining in any particular case in what
direction the last extension of range occurred. For the purposes of the study
of geographical distribution therefore, we must, except in special cases,
consider the true range of a species to comprise all the area which it
occupies regularly for any part of the year, while all those districts which it
only visits at more or less distant intervals, apparently driven by storms or
by hunger, and where it never regularly or permanently settles, should not
be included as forming part of its area of distribution.

Means of Dispersal of Reptiles and Amphibia.—If we leave out of
consideration the true marine groups—the turtles and sea-snakes—reptiles
are scarcely more fitted for traversing seas and oceans than are mammalia.
We accordingly find that in those oceanic islands which possess no
indigenous mammals, land reptiles are also generally wanting. The several
groups of these animals, however, differ considerably both in their means of
dispersal and in their power of resisting adverse conditions. Snakes are
most dependent on climate, becoming very scarce in temperate and cold
climates and entirely ceasing at 62° north latitude, and they do not ascend
very lofty mountains, ceasing at 6,000 feet elevation in the Alps. Some
inhabit deserts, others swamps and marshes, while many are adapted for a
life in forests. They swim rivers easily, but apparently have no means of
passing the sea, since they are very rarely found on oceanic islands. Lizards
are also essentially tropical, but they go somewhat farther north than
snakes, and ascend higher on the mountains, reaching 10,000 feet in the
Alps. They possess too some unknown means (probably in the egg-state) of
passing over the ocean, since they are found to inhabit many islands where
there are neither mammalia nor snakes.

The amphibia are much less sensitive to cold than are true reptiles, and they
accordingly extend much farther north, frogs being found within the arctic
circle. Their semi-aquatic life also gives them facilities for dispersal, and
their eggs are no doubt sometimes carried by aquatic birds from one pond
or stream to another. Salt water is fatal to them as well as to their eggs, and
hence it arises that they are seldom found in those oceanic islands from
which mammalia are absent. Deserts and oceans would probably form the
most effectual barriers to their dispersal; whereas both snakes and lizards
abound in deserts, and have some means of occasionally passing the ocean
which frogs and salamanders do not seem to possess.

Means of Dispersal of Fishes.—The fact that the same species of freshwater
fish often inhabit distinct river systems, proves that they have some means
of dispersal over land. The many authentic accounts of fish falling from the
atmosphere, indicate one of the means by which they may be transferred
from one river basin to another, viz., by hurricanes and whirlwinds, which
often carry up considerable quantities of water and with it fishes of small
size. In volcanic countries, also, the fishes of subterranean streams may
sometimes be thrown up by volcanic explosions, as Humboldt relates
happened in South America. Another mode by which fishes may be
distributed is by their eggs being occasionally carried away by aquatic
birds; and it is stated by Gmelin that geese and ducks during their
migrations feed on the eggs of fish, and that some of these pass through
their bodies with their vitality unimpaired.[2] Even water-beetles flying from
one pond to another might occasionally carry with them some of the smaller
eggs of fishes. But it is probable that fresh-water fish are also enabled to
migrate by changes of level causing streams to alter their course and carry
their waters into adjacent basins. On plateaux the sources of distinct river
systems often approach each other, and the same thing occurs with lateral
tributaries on the lowlands near their mouths. Such changes, although small
in extent, and occurring only at long intervals, would act very powerfully in
modifying the distribution of fresh-water fish.

Sea fish would seem at first sight to have almost unlimited means of
dispersal, but this is far from being the case. Temperature forms a complete
barrier to a large number of species, cold water being essential to many,
while others can only dwell in the warmth of the tropics. Deep water is

another barrier to large numbers of species which are adapted to shores and
shallows; and thus the Atlantic is quite as impassable a gulf to most fishes
as it is to birds. Many sea fishes migrate to a limited extent for the purpose
of depositing their spawn in favourable situations. The herring, an
inhabitant of the deep sea, comes in shoals to our coast in the breeding
season; while the salmon quits the northern seas and enters our rivers,
mounting upwards to the clear cold water near their sources to deposit its
eggs. Keeping in mind the essential fact that changes of temperature and of
depth are the main barriers to the dispersal of fish, we shall find little
difficulty in tracing the causes that have determined their distribution.

Means of Dispersal of Mollusca.—The marine, fresh-water, and land
mollusca are three groups whose powers of dispersal and consequent
distribution are very different, and must be separately considered. The
Pteropoda, the Ianthina, and other groups of floating molluscs, drift about
in mid-ocean, and their dispersal is probably limited chiefly by temperature,
but perhaps also by the presence of enemies or the scarcity of proper food.
The univalve and bivalve mollusca, of which the whelk and the cockle may
be taken as types, move so slowly in their adult state, that we should expect
them to have an exceedingly limited distribution; but the young of all these
are free swimming embryos, and they thus have a powerful means of
dispersal, and are carried by tides and currents so as ultimately to spread
over every shore and shoal that offers conditions favourable for their
development. The fresh water molluscs, which one might at first suppose
could not range beyond their own river-basin, are yet very widely
distributed in common with almost all other fresh water productions; and
Mr. Darwin has shown that this is due to the fact, that ponds and marshes
are constantly frequented by wading and swimming birds which are pre-
eminently wanderers, and which frequently carry away with them the seeds
of plants, and the eggs of molluscs and aquatic insects. Fresh water
molluscs just hatched were found to attach themselves to a duck's foot
suspended in an aquarium; and they would thus be easily carried from one
lake or river to another, and by the help of different species of aquatic birds,
might soon spread all over the globe. Even a water-beetle has been caught
with a small living shell (Ancylus) attached to it; and these fly long
distances and are liable to be blown out to sea, one having been caught on
board the Beagle when forty-five miles from land. Although fresh water

molluscs and their eggs must frequently be carried out to sea, yet this
cannot lead to their dispersal, since salt water is almost immediately fatal to
them; and we are therefore forced to conclude that the apparently
insignificant and uncertain means of dispersal above alluded to are really
what have led to their wide distribution. The true land-shells offer a still
more difficult case, for they are exceedingly sensitive to the influence of
salt water; they are not likely to be carried by aquatic birds, and yet they are
more or less abundant all over the globe, inhabiting the most remote
oceanic islands. It has been found, however, that land-shells have the power
of lying dormant a long time. Some have lived two years and a half shut up
in pill boxes; and one Egyptian desert snail came to life after having been
glued down to a tablet in the British Museum for four years!

We are indebted to Mr. Darwin for experiments on the power of land shells
to resist sea water, and he found that when they had formed a membranous
diaphragm over the mouth of the shell they survived many days' immersion
(in one case fourteen days); and another experimenter, quoted by Mr.
Darwin, found that out of one hundred land shells immersed for a fortnight
in the sea, twenty-seven recovered. It is therefore quite possible for them to
be carried in the chinks of drift wood for many hundred miles across the
sea, and this is probably one of the most effectual modes of their dispersal.
Very young shells would also sometimes attach themselves to the feet of
birds walking or resting on the ground, and as many of the waders often go
far inland, this may have been one of the methods of distributing species of
land shells; for it must always be remembered that nature can afford to wait,
and that if but once in a thousand years a single bird should convey two or
three minute snails to a distant island, this is all that is required for us to
find that island well stocked with a great and varied population of land
shells.

Means of Dispersal of Insects and the Barriers which Limit their Range.—
Winged insects, as a whole, have perhaps more varied means of dispersal
over the globe than any other highly organised animals. Many of them can
fly immense distances, and the more delicate ones are liable to be carried by
storms and hurricanes over a wide expanse of ocean. They are often met
with far out at sea. Hawk-moths frequently fly on board ships as they
approach the shores of tropical countries, and they have sometimes been

captured more than 250 miles from the nearest land. Dragon-flies came on
board the Adventure frigate when fifty miles off the coast of South America.
A southerly wind brought flies in myriads to Admiral Smyth's ship in the
Mediterranean when he was 100 miles distant from the coast of Africa. A
large Indian beetle (Chrysochroa ocellata) was quite recently caught alive
in the Bay of Bengal by Captain Payne of the barque William Mansoon, 273
miles from the nearest land. Darwin caught a locust 370 miles from land;
and in 1844 swarms of locusts several miles in extent, and as thick as the
flakes in a heavy snowstorm, visited Madeira. These must have come with
perfect safety more than 300 miles; and as they continued flying over the
island for a long time, they could evidently have travelled to a much greater
distance. Numbers of living beetles belonging to seven genera, some
aquatic and some terrestrial, were caught by Mr. Darwin in the open sea,
seventeen miles from the coast of South America, and they did not seem
injured by the salt water. Almost all the accidental causes that lead to the
dispersal of the higher animals would be still more favourable for insects.
Floating trees could carry hundreds of insects for one bird or mammal; and
so many of the larvæ, eggs, and pupæ of insects have their abode in solid
timber, that they might survive being floated immense distances. Great
numbers of tropical insects have been captured in the London docks, where
they have been brought in foreign timber; and some have emerged from
furniture after remaining torpid for many years. Most insects have the
power of existing weeks or months without food, and some are very
tenacious of life. Many beetles will survive immersion for hours in strong
spirit; and water a few degrees below the boiling point will not always kill
them. We can therefore easily understand how, in the course of ages insects
may become dispersed by means which would be quite inadequate in the
case of the higher animals. The drift-wood and tropical fruits that reach
Ireland and the Orkneys; the double cocoa-nuts that cross the Indian ocean
from the Seychelle Islands to the coast of Sumatra; the winds that carry
volcanic dust and ashes for thousands of miles; the hurricanes that travel in
their revolving course over wide oceans; all indicate means by which a few
insects may, at rare intervals be carried to remote regions, and become the
progenitors of a group of allied forms.

But the dispersal of insects requires to be looked at from another point of
view. They are, of all animals, perhaps the most wonderfully adapted for

special conditions; and are so often fitted to fill one place in nature and one
only, that the barriers against their permanent displacement are almost as
numerous and as effective as their means of dispersal. Hundreds of species
of lepidoptera, for example, can subsist in the larva state only on one
species of plant; so that even if the perfect insects were carried to a new
country, the continuance of the race would depend upon the same or a
closely allied plant being abundant there. Other insects require succulent
vegetable food all the year round, and are therefore confined to tropical
regions; some can live only in deserts, others in forests; some are dependent
on water-plants, some on mountain-vegetation. Many are so intimately
connected with other insects during some part of their existence that they
could not live without them; such are the parasitical hymenoptera and
diptera, and those mimicking species whose welfare depends upon their
being mistaken for something else. Then again, insects have enemies in
every stage of their existence—the egg, the larva, the pupa, and the perfect
form; and the abundance of any one of these enemies may render their
survival impossible in a country otherwise well suited to them. Ever bearing
in mind these two opposing classes of facts, we shall not be surprised at the
enormous range of some groups of insects, and at the extreme localization
of others; and shall be able to give a rational account of many phenomena
of distribution that would otherwise seem quite unintelligible.

CHAPTER III.

DISTRIBUTION AS AFFECTED BY THE CONDITIONS AND
C H A N G E S O F T H E E A RT H ' S S U R FA C E .

The distribution of animals over the earth's surface, is evidently dependent
in great measure upon those grand and important characteristics of our
globe, the study of which is termed physical geography. The proportion of
land and water; the outlines and distribution of continents; the depth of seas
and oceans; the position of islands; the height, direction, and continuity of
mountain chains; the position and extent of deserts, lakes, and forests; the
direction and velocity of ocean currents, as well as of prevalent winds and
hurricanes; and lastly, the distribution of heat and cold, of rain, snow, and
ice, both in their means and in their extremes, have all to be considered
when we endeavour to account for the often unequal and unsymmetrical
manner in which animals are dispersed over the globe. But even this
knowledge is insufficient unless we inquire further as to the evidence of
permanence possessed by each of these features, in order that we may give
due weight to the various causes that have led to the existing facts of animal
distribution.

Land and Water.—The well-known fact that nearly three-fourths of the
surface of the earth is occupied by water, and but a little more than one-
fourth by land, is important as indicating the vast extent of ocean by which
many of the continents and islands are separated from each other. But there
is another fact which greatly increases its importance, namely, that the mean
height of the land is very small compared with the mean depth of the sea. It
has been estimated by Humboldt that the mean height of all the land surface
does not exceed a thousand feet, owing to the comparative narrowness of
mountain ranges and the great extent of alluvial plains and valleys; the
ocean bed, on the contrary, not only descends deeper than the tops of the
highest mountains rise above its surface, but these profound depths are
broad sunken plains, while the shallows correspond to the mountain ranges,
so that its mean depth is, as nearly as can be estimated, twelve thousand
feet.[3] Hence, as the area of water is three times that of the land, the total
cubical contents of the land, above the sea level, would be only that of the
waters which are below that level. The important result follows, that

whereas it is scarcely possible that in past times the amount of land surface
should ever greatly have exceeded that which now exists, it is just possible
that all the land may have been at some time submerged; and therefore in
the highest degree probable that among the continual changes of land and
sea that have been always going on, the amount of land surface has often
been much less than it is now. For the same reason it is probable that there
have been times when large masses of land have been more isolated from
the rest than they are at present; just as South America would be if North
America were submerged, or as Australia would become if the Malay
Archipelago were to sink beneath the ocean. It is also very important to
bear in mind the fact insisted on by Sir Charles Lyell, that the shallow parts
of the ocean are almost always in the vicinity of land; and that an amount of
elevation that would make little difference to the bed of the ocean, would
raise up extensive tracts of dry land in the vicinity of existing continents. It
is almost certain, therefore, that changes in the distribution of land and sea
must have taken place more frequently by additions to, or modifications of
pre-existing land, than by the upheaval of entirely new continents in mid-
ocean. These two principles will throw light upon two constantly recurring
groups of facts in the distribution of animals,—the restriction of peculiar
forms to areas not at present isolated,—and on the other hand, the
occurrence of allied forms in lands situated on opposite shores of the great
oceans.

Continental Areas.—Although the dry land of the earth's surface is
distributed with so much irregularity, that there is more than twice as much
north of the equator as there is south of it, and about twice as much in the
Asiatic as in the American hemisphere; and, what is still more
extraordinary, that on a hemisphere of which a point in St. George's
Channel between England and Ireland is the centre, the land is nearly equal
in extent to the water, while in the opposite hemisphere it is in the
proportion of only one-eighth,—yet the whole of the land is almost
continuous. It consists essentially of only three masses: the American, the
Asia-African, and the Australian. The two former are only separated by
thirty-six miles of shallow sea at Behring's Straits, so that it is possible to
go from Cape Horn to Singapore or the Cape of Good Hope without ever
being out of sight of land; and owing to the intervention of the numerous
islands of the Malay Archipelago the journey might be continued under the

same conditions as far as Melbourne and Hobart Town. This curious fact, of
the almost perfect continuity of all the great masses of land notwithstanding
their extremely irregular shape and distribution, is no doubt dependent on
the circumstances just alluded to; that the great depth of the oceans and the
slowness of the process of upheaval, has almost always produced the new
lands either close to, or actually connected with pre-existing lands; and this
has necessarily led to a much greater uniformity in the distribution of
organic forms, than would have prevailed had the continents been more
completely isolated from each other.

The isthmuses which connect Africa with Asia, and North with South
America, are, however, so small and insignificant compared with the vast
extent of the countries they unite that we can hardly consider them to form
more than a nominal connection. The Isthmus of Suez indeed, being itself a
desert, and connecting districts which for a great distance are more or less
desert also, does not effect any real union between the luxuriant forest-clad
regions of intertropical Asia and Africa. The Isthmus of Panama is a more
effectual line of union, since it is hilly, well watered, and covered with
luxuriant vegetation; and we accordingly find that the main features of
South American zoology are continued into Central America and Mexico.
In Asia a great transverse barrier exists, dividing that continent into a
northern and southern portion; and as the lowlands occur on the south and
the highlands on the north of the great mountain range, which is situated not
far beyond the tropic, an abrupt change of climate is produced; so that a belt
of about a hundred miles wide, is all that intervenes between a luxuriant
tropical region and an almost arctic waste. Between the northern part of
Asia, and Europe, there is no barrier of importance; and it is impossible to
separate these regions as regards the main features of animal life. Africa,
like Asia, has a great transverse barrier, but it is a desert instead of a
mountain chain; and it is found that this desert is a more effectual barrier to
the diffusion of animals than the Mediterranean Sea; partly because it
coincides with the natural division of a tropical from a temperate climate,
but also on account of recent geological changes which we shall presently
allude to. It results then from this outline sketch of the earth's surface, that
the primary divisions of the geographer correspond approximately with
those of the zoologist. Some large portion of each of the popular divisions
forms the nucleus of a zoological region; but the boundaries are so changed

that the geographer would hardly recognise them: it has, therefore, been
found necessary to give them those distinct names which will be fully
explained in our next chapter.

Recent Changes in the Continental Areas.—The important fact has been
now ascertained, that a considerable portion of the Sahara south of Algeria
and Morocco was under water at a very recent epoch. Over much of this
area sea-shells, identical with those now living in the Mediterranean, are
abundantly scattered, not only in depressions below the level of the sea but
up to a height of 900 feet above it. Borings for water made by the French
government have shown, that these shells occur twenty feet deep in the
sand; and the occurrence of abundance of salt, sometimes even forming
considerable hills, is an additional proof of the disappearance of a large
body of salt water. The common cockle is one of the most abundant of the
shells found; and the Rev. H. B. Tristram discovered a new fish, in a salt
lake nearly 300 miles inland, but which has since been found to inhabit the
Gulf of Guinea. Connected with this proof of recent elevation in the Sahara,
we have most interesting indications of subsidence in the area of the
Mediterranean, which were perhaps contemporaneous. Sicily and Malta are
connected with Africa by a submerged bank from 300 to 1,200 feet below
the surface; while the depth of the Mediterranean, both to the east and west,
is enormous, in some parts more than 13,000 feet; and another submerged
bank with a depth of 1,000 feet occurs at the straits of Gibraltar. In caves in
Sicily, remains of the living African elephant have been found by Baron
Anca; and in other caves Dr. Falconer discovered remains of the Elephas
antiquus and of two species of Hippopotamus. In Malta, three species of
elephant have been discovered by Captain Spratt; a large one closely allied
to E. antiquus and two smaller ones not exceeding five feet high when
adult. These facts clearly indicate, that when North Africa was separated by
a broad arm of the sea from the rest of the continent, it was probably
connected with Europe; and this explains why zoologists find themselves
obliged to place it along with Europe in the same zoological region.

Besides this change in the level of the Sahara and the Mediterranean basin,
Europe has undergone many fluctuations in its physical geography in very
recent times. In Wales, abundance of sea-shells of living species have been
found at an elevation of 1,300 feet; and in Sardinia there is proof of an

elevation of 300 feet since the human epoch; and these are only samples of
many such changes of level. But these changes, though very important
locally and as connected with geological problems, need not be further
noticed here; as they were not of a nature to affect the larger features of the
earth's surface or to determine the boundaries of great zoological regions.

The only other recent change of great importance which can be adduced to
illustrate our present subject, is that which has taken place between North
and South America. The living marine shells of the opposite coasts of the
isthmus of Panama, as well as the corals and fishes, are generally of distinct
species, but some are identical and many are closely allied; the West Indian
fossil shells and corals of the Miocene period, however, are found to be
largely identical with those of the Pacific coast. The fishes of the Atlantic
and Pacific shores of America are as a rule very distinct; but Dr. Günther
has recently shown that a considerable number of species inhabiting the
seas on opposite sides of the isthmus are absolutely identical. These facts
certainly indicate, that during the Miocene epoch a broad channel separated
North and South America; and it seems probable that a series of elevations
and subsidences have taken place uniting and separating them at different
epochs; the most recent submersion having lasted but a short time, and thus,
while allowing the passage of abundance of locomotive fishes, not
admitting of much change in the comparatively stationary mollusca.

The Glacial Epoch as affecting the Distribution of Animals.—The
remarkable refrigeration of climate in the northern hemisphere within the
epoch, of existing species, to which the term Glacial epoch is applied,
together with the changes of level that accompanied and perhaps assisted to
produce it, has been one of the chief agents in determining many of the
details of the existing distribution of animals in temperate zones. A
comparison of the effects produced by existing glaciers with certain
superficial phenomena in the temperate parts of Europe and North America,
renders it certain that between the Newer Pliocene and the Recent epochs, a
large portion of the northern hemisphere must have been covered with a
sheet of ice several thousand feet thick, like that which now envelopes the
interior of Greenland. Much further south the mountains were covered with
perpetual snow, and sent glaciers down every valley; and all the great
valleys on the southern side of the Alps poured down streams of ice which

stretched far out into the plains of Northern Italy, and have left their débris
in the form of huge mountainous moraines, in some cases more than a
thousand feet high. In Canada and New Hampshire the marks of moving ice
are found on the tops of mountains from 3,000 to 5,000 feet high; and the
whole surface of the country around and to the north of the great lakes is
scored by glaciers. Wherever the land was submerged during a part of this
cold period, a deposit called boulder-clay, or glacial-drift has been formed.
This is a mass of sand, clay, or gravel, full of angular or rounded stones of
all sizes, up to huge blocks as large as a cottage; and especially
characterized by these stones being distributed confusedly through it, the
largest being as often near the top as near the bottom, and never sorted into
layers of different sizes as in materials carried by water. Such deposits are
known to be formed by glaciers and icebergs; when deposited on the land
by glaciers they form moraines, when carried into water and thus spread
with more regularity over a wider area they form drift. This drift is rarely
found except where there is other evidence of ice-action, and never south of
the 40th parallel of latitude, to which in the northern hemisphere signs of
ice-action extend. In the southern hemisphere, in Patagonia and in New
Zealand, exactly similar phenomena occur.

A very interesting confirmation of the reality of this cold epoch is derived
from the study of fossil remains. Both the plants and animals of the
Miocene period indicate that the climate of Central Europe was decidedly
warmer or more equable than it is now; since the flora closely resembled
that of the Southern United States, with a likeness also to that of Eastern
Asia and Australia. Many of the shells were of tropical genera; and there
were numbers of large mammalia allied to the elephant, rhinoceros, and
tapir. At the same time, or perhaps somewhat earlier, a temperate climate
extended into the arctic regions, and allowed a magnificent vegetation of
shrubs and forest trees, some of them evergreen, to flourish within twelve
degrees of the Pole. In the Pliocene period we find ourselves among forms
implying a climate very little different from the present; and our own Crag
formation furnishes evidence of a gradual refrigeration of climate; since its
three divisions, the Coralline, Red, and Norwich Crags, show a decreasing
number of southern, and an increasing number of northern species, as we
approach the Glacial epoch. Still later than these we have the shells of the
drift, almost all of which are northern and many of them arctic species.

Among the mammalia indicative of cold, are the mammoth and the
reindeer. In gravels and cave-deposits of Post-Pliocene date we find the
same two animals, which soon disappear as the climate approached its
present condition; and Professor Forbes has given a list of fifty shells which
inhabited the British seas before the Glacial epoch and inhabit it still, but
are all wanting in the glacial deposits. The whole of these are found in the
Newer Pliocene strata of Sicily and the south of Europe, where they
escaped destruction during the glacial winter.

There are also certain facts in the distribution of plants, which are so well
explained by the Glacial epoch that they may be said to give an additional
confirmation to it. All over the northern hemisphere within the glaciated
districts, the summits of lofty mountains produce plants identical with those
of the polar regions. In the celebrated case of the White Mountains in New
Hampshire, United States (latitude 45°), all the plants on the summit are
arctic species, none of which exist in the lowlands for near a thousand miles
further north. It has also been remarked that the plants of each mountain are
more especially related to those of the countries directly north of it. Thus,
those of the Pyrenees and of Scotland are Scandinavian, and those of the
White Mountains are all species found in Labrador. Now, remembering that
we have evidence of an exceedingly mild and uniform climate in the arctic
regions during the Miocene period and a gradual refrigeration from that
time, it is evident that with each degree of change more and more hardy
plants would be successively driven southwards; till at last the plains of the
temperate zone would be inhabited by plants, which were once confined to
alpine heights or to the arctic regions. As the icy mantle gradually melted
off the face of the earth these plants would occupy the newly exposed soil,
and would thus necessarily travel in two directions, back towards the arctic
circle and up towards the alpine peaks. The facts are thus exactly explained
by a cause which independent evidence has proved to be a real one, and
every such explanation is an additional proof of the reality of the cause. But
this explanation implies, that in cases where the Glacial epoch cannot have
so acted alpine plants should not be northern plants; and a striking proof of
this is to be found on the Peak of Teneriffe, a mountain 12,000 feet high. In
the uppermost 4,500 feet of this mountain above the limit of trees, Von
Buch found only eleven species of plants, eight of which were peculiar; but
the whole were allied to those found at lower elevations. On the Alps or

Pyrenees at this elevation, there would be a rich flora comprising hundreds
of arctic plants; and the absence of anything corresponding to them in this
case, in which their ingress was cut off by the sea, is exactly what the
theory leads us to expect.

Changes of Vegetation as affecting the Distribution of Animals.—As so
many animals are dependent on vegetation, its changes immediately affect
their distribution. A remarkable example of this is afforded by the pre-
historic condition of Denmark, as interpreted by means of the peat-bogs and
kitchen-middens. This country is now celebrated for its beech-trees; oaks
and pines being scarce; and it is known to have had the same vegetation in
the time of the Romans. In the peat-bogs, however, are found deposits of
oak trees; and deeper still pines alone occur. Now the kitchen-middens tell
us much of the natural history of Denmark in the early Stone period; and a
curious confirmation of the fact that Denmark like Norway was then chiefly
covered with pine forests is obtained by the discovery, that the Capercailzie
was then abundant, a bird which feeds almost exclusively on the young
shoots and seeds of pines and allied plants. The cause of this change in the
vegetation is unknown; but from the known fact that when forests are
destroyed trees, of a different kind usually occupy the ground, we may
suppose that some such change as a temporary submergence might cause an
entirely different vegetation and a considerably modified fauna to occupy
the country.

Organic Changes as affecting Distribution.—We have now briefly touched
on some of the direct effects of changes in physical geography, climate, and
vegetation, on the distribution of animals; but the indirect effects of such
changes are probably of quite equal, if not of greater importance. Every
change becomes the centre of an ever-widening circle of effects. The
different members of the organic world are so bound together by complex
relations, that any one change generally involves numerous other changes,
often of the most unexpected kind. We know comparatively little of the way
in which one animal or plant is bound up with others, but we know enough
to assure us that groups the most apparently disconnected are often
dependent on each other. We know, for example, that the introduction of
goats into St. Helena utterly destroyed a whole flora of forest trees; and
with them all the insects, mollusca, and perhaps birds directly or indirectly

dependent on them. Swine, which ran wild in Mauritius, exterminated the
Dodo. The same animals are known to be the greatest enemies of venomous
serpents. Cattle will, in many districts, wholly prevent the growth of trees;
and with the trees the numerous insects dependent on those trees, and the
birds which fed upon the insects, must disappear, as well as the small
mammalia which feed on the fruits, seeds, leaves, or roots. Insects again
have the most wonderful influence on the range of mammalia. In Paraguay
a certain species of fly abounds which destroys new-born cattle and horses;
and thus neither of these animals have run wild in that country, although
they abound both north and south of it. This inevitably leads to a great
difference in the vegetation of Paraguay, and through that to a difference in
its insects, birds, reptiles, and wild mammalia. On what causes the existence
of the fly depends we do not know, but it is not improbable that some
comparatively slight changes in the temperature or humidity of the air at a
particular season, or the introduction of some enemy might lead to its
extinction or banishment. The whole face of the country would then soon be
changed: new species would come in, while many others would be unable
to live there; and the immediate cause of this great alteration would
probably be quite imperceptible to us, even if we could watch it in progress
year by year. So, in South Africa, the celebrated Tsetse fly inhabits certain
districts having well defined limits; and where it abounds no horses, dogs,
or cattle can live. Yet asses, zebras, and antelopes are unaffected by it. So
long as this fly continues to exist, there is a living barrier to the entrance of
certain animals, quite as effectual as a lofty mountain range or a wide arm
of the sea. The complex relations of one form of life with others is nowhere
better illustrated than in Mr. Darwin's celebrated case of the cats and clover,
as given in his Origin of Species, 6th ed., p. 57. He has observed that both
wild heartsease and red-clover are fertilized in this country by humble-bees
only, so that the production of seed depends on the visits of these insects. A
gentleman who has specially studied humble-bees finds that they are largely
kept down by field-mice, which destroy their combs and nests. Field-mice
in their turn are kept down by cats; and probably also by owls; so that these
carnivorous animals are really the agents in rendering possible the
continued existence of red-clover and wild heartsease. For if they were
absent, the field-mice having no enemies, would multiply to such an extent
as to destroy all the humble-bees; and these two plants would then produce
no seed and soon become extinct.

Mr. Darwin has also shown that one species often exterminates another
closely allied to it, when the two are brought into contact. One species of
swallow and thrush are known to have increased at the expense of allied
species. Rats, carried all over the world by commerce, are continually
extirpating other species of rats. The imported hive-bee is, in Australia,
rapidly exterminating a native stingless bee. Any slight change, therefore, of
physical geography or of climate, which allows allied species hitherto
inhabiting distinct areas to come into contact, will often lead to the
extermination of one of them; and this extermination will be effected by no
external force, by no actual enemy, but merely because the one is slightly
better adapted to live, to increase, and to maintain itself under adverse
circumstances, than the other.

Now if we consider carefully the few suggestive facts here referred to (and
many others of like import are to be found in Mr. Darwin's various works),
we shall be led to conclude that the several species, genera, families, and
orders, both of animals and vegetables which inhabit any extensive region,
are bound together by a series of complex relations; so that the increase,
diminution, or extermination of any one, may set in motion a series of
actions and reactions more or less affecting a large portion of the whole,
and requiring perhaps centuries of fluctuation before the balance is restored.
The range of any species or group in such a region, will in many cases
(perhaps in most) be determined, not by physical barriers, but by the
competition of other organisms. Where barriers have existed from a remote
epoch, they will at first have kept back certain animals from coming in
contact with each other; but when the assemblage of organisms on the two
sides of the barrier have, after many ages, come to form a balanced organic
whole, the destruction of the barrier may lead to a very partial intermingling
of the peculiar forms of the two regions. Each will have become modified
in special ways adapted to the organic and physical conditions of the
country, and will form a living barrier to the entrance of animals less
perfectly adapted to those conditions. Thus while the abolition of ancient
barriers will always lead to much intermixture of forms, much
extermination and wide-spread alteration in some families of animals; other
important groups will be unable materially to alter their range; or they may
make temporary incursions into the new territory, and be ultimately driven
back to very near their ancient limits.

In order to make this somewhat difficult subject more intelligible, it may be
well to consider the probable effects of certain hypothetical conditions of
the earth's surface:—

1. If the dry land of the globe had been from the first continuous, and
nowhere divided up by such boundaries as lofty mountain ranges, wide
deserts, or arms of the sea, it seems probable that none of the larger groups
(as orders, tribes, or families,) would have a limited range; but, as is to
some extent the case in tropical America east of the Andes, every such
group would be represented over the whole area, by countless minute
modifications of form adapted to local conditions.

2. One great physical barrier would, however, even then exist; the hot
equatorial zone would divide the faunas and floras of the colder regions of
the northern and southern hemispheres from any chance of intermixture.
This one barrier would be more effectual than it is now, since there would
be no lofty mountain ranges to serve as a bridge for the partial interchange
of northern and southern forms.

3. If such a condition of the earth as here supposed continued for very long
periods, we may conceive that the action and reaction of the various
organisms on each other, combined with the influence of very slowly
changing physical conditions, would result in an almost perfect organic
balance, which would be manifested by a great stability in the average
numbers, the local range, and the peculiar characteristics of every species.

4. Under such a condition of things it is not improbable that the total
number of clearly differentiated specific forms might be much greater than
it is now, though the number of generic and family types might perhaps be
less; for dominant species would have had ample time to spread into every
locality where they could exist, and would then become everywhere
modified into forms best suited to the permanent local conditions.

5. Now let us consider what would be the probable effect of the introduction
of a barrier, cutting off a portion of this homogeneous and well-balanced
world. Suppose, for instance, that a subsidence took place, cutting off by a

wide arm of the sea a large and tolerably varied island. The first and most
obvious result would be that the individuals of a number of species would
be divided into two portions, while others, the limits of whose range agreed
approximately with the line of subsidence, would exist in unimpaired
numbers on the new island or on the main land. But the species whose
numbers were diminished and whose original area was also absolutely
diminished by the portion now under the sea, would not be able to hold
their ground against the rival forms whose numbers were intact. Some
would probably diminish and rapidly die out; others which produced
favourable varieties, might be so modified by natural selection as to
maintain their existence under a different form; and such changes would
take place in varying modes on the two sides of the new strait.

6. But the progress of these changes would necessarily affect the other
species in contact with them. New places would be opened in the economy
of nature which many would struggle to obtain; and modification would go
on in ever-widening circles and very long periods of time might be required
to bring the whole again into a state of equilibrium.

7. A new set of factors would in the meantime have come into play. The
sinking of land and the influx of a large body of water could hardly take
place without producing important climatal changes. The temperature, the
winds, the rains, might all be affected, and more or less changed in duration
and amount. This would lead to a quite distinct movement in the organic
world. Vegetation would certainly be considerably affected, and through
this the insect tribes. We have seen how closely the life of the higher
animals is often bound up with that of insects; and thus a set of changes
might arise that would modify the numerical proportions, and even the
forms and habits of a great number of species, would completely
exterminate some, and raise others from a subordinate to a dominant
position. And all these changes would occur differently on opposite sides of
the strait, since the insular climate could not fail to differ considerably from
that of the continent.

8. But the two sets of changes, as above indicated, produced by different
modes of action of the same primary cause, would act and react on each

other; and thus lead to such a far-spreading disturbance of the organic
equilibrium as ultimately perhaps to affect in one way or another, every
form of life upon the earth.

This hypothetical case is useful as enabling us better to realize how wide-
spreading might be the effects of one of the simplest changes of physical
geography, upon a compact mass of mutually adapted organisms. In the
actual state of things, the physical changes that occur and have occurred
through all geological epochs are larger and more varied. Almost every mile
of land surface has been again and again depressed beneath the ocean; most
of the great mountain chains have either originated or greatly increased in
height during the Tertiary period; marvellous alterations of climate and
vegetation have taken place over half the land-surface of the earth; and all
these vast changes have influenced a globe so cut up by seas and oceans, by
deserts and snow-clad mountains, that in many of its more isolated land-
masses ancient forms of life have been preserved, which, in the more
extensive and more varied continents have long given way to higher types.
How complex then must have been the actions and reactions such a state of
things would bring about; and how impossible must it be for us to guess, in
most cases, at the exact nature of the forces that limit the range of some
species and cause others to be rare or to become extinct! All that we can in
general hope to do is, to trace out, more or less hypothetically, some of the
larger changes in physical geography that have occurred during the ages
immediately preceeding our own, and to estimate the effect they will
probably have produced on animal distribution. We may then, by the aid of
such knowledge as to past organic mutations as the geological record
supplies us with, be able to determine the probable birthplace and
subsequent migrations of the more important genera and families; and thus
obtain some conception of that grand series of co-ordinated changes in the
earth and its inhabitants, whose final result is seen in the forms and the
geographical distribution of existing animals.

CHAPTER IV.

ON ZOOLOGICAL REGIONS.

To the older school of Naturalists the native country of an animal was of little
importance, except in as far as climates differed. Animals were supposed to be
specially adapted to live in certain zones or under certain physical conditions,
and it was hardly recognised that apart from these conditions there was any
influence in locality which could materially affect them. It was believed that,
while the animals of tropical, temperate, and arctic climates, essentially
differed; those of the tropics were essentially alike all over the world. A group
of animals was said to inhabit the "Indies;" and important differences of
structure were often overlooked from the idea, that creatures equally adapted to
live in hot countries and with certain general resemblances, would naturally be
related to each other. Thus the Toucans and Hornbills, the Humming-Birds and
Sun-Birds, and even the Tapirs and the Elephants, came to be popularly
associated as slightly modified varieties of tropical forms of life; while to
naturalists, who were acquainted with the essential differences of structure, it
was a never-failing source of surprise, that under climates and conditions so
apparently identical, such strangely divergent forms should be produced.

To the modern naturalist, on the other hand, the native country (or "habitat" as it
is technically termed) of an animal or a group of animals, is a matter of the first
importance; and, as regards the general history of life upon the globe, may be
considered to be one of its essential characters. The structure, affinities, and
habits of a species, now form only a part of its natural history. We require also
to know its exact range at the present day and in prehistoric times, and to have
some knowledge of its geological age, the place of its earliest appearance on the
globe, and of the various extinct forms most nearly allied to it. To those who
accept the theory of development as worked out by Mr. Darwin, and the views
as to the general permanence and immense antiquity of the great continents and
oceans so ably developed by Sir Charles Lyell, it ceases to be a matter of
surprise that the tropics of Africa, Asia, and America should differ in their
productions, but rather that they should have anything in common. Their
similarity, not their diversity, is the fact that most frequently puzzles us.

The more accurate knowledge we have of late years obtained of the productions
of many remote regions, combined with the greater approaches that have been
made to a natural classification of the higher animals, has shown, that every

continent or well-marked division of a continent, every archipelago and even
every island, presents problems of more or less complexity to the student of the
geographical distribution of animals. If we take up the subject from the
zoological side, and study any family, order, or even extensive genus, we are
almost sure to meet with some anomalies either in the present or past
distribution of the various forms. Let us adduce a few examples of these
problems.

Deer have a wonderfully wide range, over the whole of Europe, Asia, and North
and South America; yet in Africa south of the great desert there are none. Bears
range over the whole of Europe, Asia, and North America, and true pigs of the
genus Sus, over all Europe and Asia and as far as New Guinea; yet both bears
and pigs, like deer, are absent from Tropical and South Africa.

Again, the West Indian islands possess very few Mammalia, all of small size
and allied to those of America, except one genus; and that belongs to an Order,
"Insectivora," entirely absent from South America, and to a family, "Centetidæ,"
all the other species of which inhabit Madagascar only. And as if to add force to
this singular correspondence we have one Madagascar species of a beautiful
day-flying Moth, Urania, all the other species of which inhabit tropical
America. These insects are gorgeously arrayed in green and gold, and are quite
unlike any other Lepidoptera upon the globe.

The island of Ceylon generally agrees in its productions with the Southern part
of India; yet it has several birds which are allied to Malayan and not to Indian
groups, and a fine butterfly of the genus Hestia, as well as several genera of
beetles, which are purely Malayan.

Various important groups of animals are distributed in a way not easy to
explain. The anthropoid apes in West Africa and Borneo; the tapirs in Malaya
and South America; the camel tribe in the deserts of Asia and the Andes; the
trogons in South America and Tropical Asia, with one species in Africa; the
marsupials in Australia and America, are examples.

The cases here adduced (and they might be greatly multiplied) are merely to
show the kind of problems with which the naturalist now has to deal; and in
order to do so he requires some system of geographical arrangement, which
shall serve the double purpose of affording a convenient subdivision of his

subject, and at the same time of giving expression to the main results at which
he has arrived. Hence the recent discussions on "Zoological Regions," or, what
are the most natural primary divisions of the earth as regards its forms of animal
life.

The divisions in use till quite recently were of two kinds; either those ready
made by geographers, more especially the quarters or continents of the globe; or
those determined by climate and marked out by certain parallels of latitude or
by isothermal lines. Either of these methods was better than none at all; but
from the various considerations explained in the preceding chapters, it will be
evident, that such divisions must have often been very unnatural, and have
disguised many of the most important and interesting phenomena which a study
of the distribution of animals presents to us.

The merit of initiating a more natural system, that of determining zoological
regions, not by any arbitrary or a priori consideration but by studying the actual
ranges of the more important groups of animals, is due to Mr. Sclater, who, in
1857, established six primary zoological regions from a detailed examination of
the distribution of the chief genera and families of Birds. Before stating what
these regions are, what objections have been made to them, what other divisions
have been since proposed, and what are those which we shall adopt in this
work, it will be well to consider the general principles which should guide us in
the choice between rival systems.

Principles on which Zoological Regions should be formed.—It will be evident
in the first place that nothing like a perfect zoological division of the earth is
possible. The causes that have led to the present distribution of animal life are
so varied, their action and reaction have been so complex, that anomalies and
irregularities are sure to exist which will mar the symmetry of any rigid system.
On two main points every system yet proposed, or that probably can be
proposed, is open to objection; they are,—1stly, that the several regions are not
of equal rank;—2ndly, that they are not equally applicable to all classes of
animals. As to the first objection, it will be found impossible to form any three
or more regions, each of which differs from the rest in an equal degree or in the
same manner. One will surpass all others in the possession of peculiar families;
another will have many characteristic genera; while a third will be mainly
distinguished by negative characters. There will also be found many
intermediate districts, which possess some of the characteristics of two well-

marked regions, with a few special features of their own, or perhaps with none;
and it will be a difficult question to decide in all cases which region should
possess this doubtful territory, or whether it should be formed into a primary
region itself. Again, two regions which have now well-marked points of
difference, may be shown to have been much more alike at a comparatively
recent geological epoch; and this, it may be said, proves their fundamental unity
and that they ought to form but one primary region. To obviate some of these
difficulties a binary or dichotomous division is sometimes proposed; that
portion of the earth which differs most from the rest being cut off as a region
equal in rank to all that remains, which is subjected again and again to the same
process.

To decide these various points it seems advisable that convenience,
intelligibility, and custom, should largely guide us. The first essential is, a
broadly marked and easily remembered set of regions; which correspond, as
nearly as truth to nature will allow, with the distribution of the most important
groups of animals. What these groups are we shall presently explain. In
determining the number, extent, and boundaries of these regions, we must be
guided by a variety of indications, since the application of fixed rules is
impossible. They should evidently be of a moderate number, corresponding as
far as practicable with the great natural divisions of the globe marked out by
nature, and which have always been recognized by geographers. There should
be some approximation to equality of size, since there is reason to believe that a
tolerably extensive area has been an essential condition for the development of
most animal forms; and it is found that, other things being equal, the numbers,
variety and importance of the forms of animal and vegetable life, do bear some
approximate relation to extent of area. Although the possession of peculiar
families or genera is the main character of a primary zoological region, yet the
negative character of the absence of certain families or genera is of equal
importance, when this absence does not manifestly depend on unsuitability to
the support of the group, and especially when there is now no physical barrier
preventing their entrance. This will become evident when we consider that the
importance of the possession of a group by one region depends on its absence
from the adjoining regions; and if there is now no barrier to its entrance, we
may be sure that there has once been one; and that the possession of the area by
a distinct and well balanced set of organisms, which must have been slowly
developed and adjusted, is the living barrier that now keeps out intruders.

When it is ascertained that the chief differences which now obtain between two
areas did not exist in Miocene or Pliocene times, the fact is one of great interest,
and enables us to speculate with some degree of probability as to the causes that
have brought about the present state of things; but it is not a reason for uniting
these two areas into one region. Our object is to represent as nearly as possible
the main features of the distribution of existing animals, not those of any or all
past geological epochs. Should we ever obtain sufficient information as to the
geography and biology of the earth at past epochs, we might indeed determine
approximately what were the Pliocene or Miocene or Eocene zoological
regions; but any attempt to exhibit all these in combination with those of our
own period, must lead to confusion.

The binary or dichotomous system, although it brings out the fundamental
differences of the respective regions, is an inconvenient one in its application,
and rather increases than obviates the difficulty as to equality or inequality of
regions; for although a, b, c, and d, may be areas of unequal zoological rank, a
being the most important, and d the least, yet this inequality will probably be
still greater if we first divide them into a, on one side, and b, c, and d, on the
other, and then, by another division, make b, an area of the second, and c, and d,
of the third rank only.

Coming to the second objection, the often incompatible distribution of different
groups of animals, affords ground for opposition to any proposed scheme of
zoological regions. There is first the radical difference between land and sea
animals; the most complete barriers to the dispersal of the one, sometimes
offering the greatest facilities for the emigration of the other, and vice versa. A
large number of marine animals, however, frequent shallow water only; and
these, keeping near the coasts, will agree generally in their distribution with
those inhabiting the land. But among land animals themselves there are very
great differences of distribution, due to certain specialities in their organization
or mode of life. These act mainly in two ways,—1stly, by affecting the facilities
with which they can be dispersed, either voluntarily or involuntarily;—2ndly,
by the conditions which enable them to multiply and establish themselves in
certain areas and not in others. When both these means of diffusion are at a
maximum, the dispersal of a group becomes universal, and ceases to have much
interest for us. This is the case with certain groups of fungi and lichens, as well
as with some of the lower animals; and in a less degree, as has been shown by
Mr. Darwin, with many fresh-water plants and animals. At the other extreme we
may place certain arboreal vertebrata such as sloths and lemurs, which have no

means of passing such barriers as narrow straits or moderately high mountains,
and whose survival in any new country they might reach, would be dependent
on the presence of suitable forests and the absence of dangerous enemies.
Almost equally, or perhaps even more restricted, are the means of permanent
diffusion of terrestrial molluscs; since these are without any but very rare and
accidental means of being safely transported across the sea; their individual
powers of locomotion are highly restricted; they are especially subject to the
attacks of enemies; and they often depend not only on a peculiar vegetation, but
on the geological character of the country, their abundance being almost in
direct proportion to the presence of some form of calcareous rocks. Between
these extremes we find animals possessed of an infinite gradation of powers to
disperse and to maintain themselves; and it will evidently be impossible that the
limits which best define the distribution of one group, should be equally true for
all others.

Which class of Animals is of most importance in determining Zoological
Regions.—To decide this question we have to consider which groups of animals
are best adapted to exhibit, by their existing distribution, the past changes and
present physical condition of the earth's surface; and at the same time, by the
abundance of their remains in the various tertiary formations will best enable us
to trace out the more recent of the series of changes, both of the earth's surface
and of its inhabitants, by which the present state of things has been brought
about. For this purpose we require a group which shall be dependent for its
means of dispersal on the distribution of land and water, and on the presence or
absence of lofty mountains, desert plains or plateaux, and great forests; since
these are the chief physical features of the earth's surface whose modifications
at successive periods we wish to discover. It is also essential that they should
not be subject to dispersal by many accidental causes; as this would inevitably
in time tend to obliterate the effect of natural barriers, and produce a scattered
distribution, the causes of which we could only guess at. Again, it is necessary
that they should be so highly organized as not to be absolutely dependent on
other groups of animals, and with so much power of adaptation as to be able to
exist in one form or another over the whole globe. And lastly, it is highly
important that the whole group should be pretty well known, and that a fairly
natural classification, especially of its minor divisions such as families and
genera, should have been arrived at; the reason for which last proviso is
explained in our next chapter, on classification.

Now in every one of these points the mammalia are preeminent; and they
possess the additional advantage of being the most highly developed class of
organized beings, and that to which we ourselves belong. We should therefore
construct our typical or standard Zoological Regions in the first place, from a
consideration of the distribution of mammalia, only bringing to our aid the
distribution of other groups to determine doubtful points. Regions so
established will be most closely in accordance with those long-enduring
features of physical geography, on which the distribution of all forms of life
fundamentally depend; and all discrepancies in the distribution of other classes
of animals must be capable of being explained, either by their exceptional
means of dispersion or by special conditions affecting their perpetuation and
increase in each locality.

If these considerations are well founded, the objections of those who study
insects or molluscs, for example,—that our regions are not true for their
departments of nature—cannot be maintained. For they will find, that a careful
consideration of the exceptional means of dispersal and conditions of existence
of each group, will explain most of the divergences from the normal distribution
of higher animals.

We shall thus be led to an intelligent comprehension of the phenomena of
distribution in all groups, which would not be the case if every specialist formed
regions for his own particular study. In many cases we should find that no
satisfactory division of the earth could be made to correspond with the
distribution even of an entire class; but we should have the coleopterist and the
lepidopterist each with his own Geography. And even this would probably not
suffice, for it is very doubtful if the detailed distribution of the Longicornes, so
closely dependent on woody vegetation, could be made to agree with that of the
Staphylinidæ or the Carabidæ which abound in many of the most barren
regions, or with that of the Scarabeidæ, largely dependent on the presence of
herbivorous mammalia. And when each of these enquirers had settled a division
of the earth into "regions" which exhibited with tolerable accuracy the
phenomena of distribution of his own group, we should have gained nothing
whatever but a very complex mode of exhibiting the bare facts of distribution.
We should then have to begin to work out the causes of the divergence of one
group from another in this respect; but as each worker would refer to his own
set of regions as the type, the whole subject would become involved in
inextricable confusion. These considerations seem to make it imperative that
one set of "regions" should be established as typical for Zoology; and it is

hoped the reasons here advanced will satisfy most naturalists that these regions
can be best determined, in the first place, by a study of the distribution of the
mammalia, supplemented in doubtful cases by that of the other vertebrates. We
will now proceed to a discussion of what these regions are.

Various Zoological Regions proposed since 1857.—It has already been pointed
out that a very large number of birds are limited by the same kind of barriers as
mammalia; it will therefore not be surprising that a system of regions formed to
suit the one, should very nearly represent the distribution of the other. Mr.
Sclater's regions are as follows:—

1. The Palæarctic Region; including Europe, Temperate Asia, and N. Africa to
the Atlas mountains.

2. The Ethiopian Region; Africa south of the Atlas, Madagascar, and the
Mascarene Islands, with Southern Arabia.

3. The Indian Region; including India south of the Himalayas, to South China,
and to Borneo and Java.

4. The Australian Region; including Celebes and Lombock, eastward to
Australia and the Pacific Islands.

5. The Nearctic Region; including Greenland, and N. America, to Northern
Mexico.

6. The Neotropical Region; including South America, the Antilles, and Southern
Mexico.

This division of the earth received great support from Dr. Günther, who, in the
Proceedings of the Zoological Society for 1858, showed that the geographical
distribution of Reptiles agreed with it very closely, the principal difference
being that the reptiles of Japan have a more Indian character than the birds, this
being especially the case with the snakes. In the volume for 1868 of the same
work, Professor Huxley discusses at considerable length the primary and
secondary zoological divisions of the earth. He gives reasons for thinking that
the most radical primary division, both as regards birds and mammals, is into a

Northern and Southern hemisphere (Arctogæa and Notogæa), the former,
however, embracing all Africa, while the latter includes only Australasia and the
Neotropical or Austro-Columbian region. Mr. Sclater had grouped his regions
primarily into Palæogæa and Neogæa, the Old and New Worlds of geographers;
a division which strikingly accords with the distribution of the passerine birds,
but not so well with that of mammalia or reptiles. Professor Huxley points out
that the Nearctic, Palæarctic, Indian, and Ethiopian regions of Mr. Sclater have
a much greater resemblance to each other than any one of them has to Australia
or to South America; and he further suggests that New Zealand alone has
peculiarities which might entitle it to rank as a primary region along with
Australasia and South America; and that a Circumpolar Province might be
conveniently recognised as of equal rank with the Palæarctic and Nearctic
provinces.

In 1866, Mr. Andrew Murray published a large and copiously illustrated volume
on the Geographical Distribution of Mammals, in which he maintains that the
great and primary mammalian regions are only four: 1st. The Palæarctic region
of Mr. Sclater, extended to include the Sahara and Nubia; 2nd. the Indo-African
region, including the Indian and Ethiopian regions of Mr. Sclater; 3rd. the
Australian region (unaltered); 4th. the American region, including both North
and South America. These are the regions as described by Mr. Murray, but his
coloured map of "Great Mammalian Regions" shows all Arctic America to a
little south of the Isothermal of 32° Fahr. as forming with Europe and North
Asia one great region.

At the meeting of the British Association at Exeter in 1869, Mr. W. T. Blanford
read a paper on the Fauna of British India, in which he maintained that a large
portion of the peninsula of India had derived its Fauna mainly from Africa; and
that the term "Indian region" of Mr. Sclater was misleading, because India
proper, if it belongs to it at all, is the least typical portion of it. He therefore
proposes to call it the "Malayan region," because in the Malay countries it is
most highly developed. Ceylon and the mountain ranges of Southern India have
marked Malay affinities.

In 1871 Mr. E. Blyth published in Nature "A suggested new Division of the
Earth into Zoological Regions," in which he indicates seven primary divisions
or regions, subdivided into twenty-six sub-regions. The seven regions are
defined as follows: 1. The Boreal region; including the whole of the Palæarctic

and Nearctic regions of Mr. Sclater along with the West Indies, Central
America, the whole chain of the Andes, with Chili and Patagonia. 2. The
Columbian region; consisting of the remaining part of South America. 3. The
Ethiopian region; comprising besides that region of Mr. Sclater, the valley of the
Jordan, Arabia, and the desert country towards India, with all the plains and
table lands of India and the northern half of Ceylon. 4. The Lemurian region;
consisting of Madagascar and its adjacent islands. 5. The Austral-Asian region;
which is the Indian region of Mr. Sclater without the portion taken to be added
to the Ethiopian region. 6. The Melanesian region; which is the Australian
region of Mr. Sclater without New Zealand and the Pacific Islands, which form
7. the Polynesian region. Mr. Blyth thinks this is "a true classification of
zoological regions as regards mammalia and birds."

In an elaborate paper on the birds of Eastern North America, their distribution
and migrations (Bulletin of Museum of Comparative Zoology, Cambridge,
Massachusetts, Vol. 2), Mr. J. A. Allen proposes a division of the earth in
accordance with what he terms, "the law of circumpolar distribution of life in
zones," as follows: 1. Arctic realm. 2. North temperate realm. 3. American
tropical realm. 4. Indo-African tropical realm. 5. South American tropical realm.
6. African temperate realm. 7. Antarctic realm. 8. Australian realm. Some of
these are subdivided into regions; (2) consisting of the American and the
Europæo-Asiatic regions; (4) into the African and Indian regions; (8) into the
tropical Australian region, and one comprising the southern part of Australia
and New Zealand. The other realms each form a single region.

Discussion of proposed Regions.—Before proceeding to define the regions
adopted in this work, it may be as well to make a few remarks on some of the
preceding classifications, and to give the reasons which seem to render it
advisable to adopt very few of the suggested improvements on Mr. Sclater's
original proposal. Mr. Blyth's scheme is one of the least natural, and also the
most inconvenient. There can be little use in the knowledge that a group of
animals is found in the Boreal Region, if their habitat might still be either
Patagonia, the West Indies, or Japan; and it is difficult to see on what principle
the Madagascar group of islands is made of equal rank with this enormous
region, seeing that its forms of life have marked African affinities. Neither does
it seem advisable to adopt the Polynesian Region, or that comprising New
Zealand alone (as hinted at by Professor Huxley and since adopted by Mr.
Sclater in his Lectures on Geographical Distribution at the Zoological Gardens
in May 1874), because it is absolutely without indigenous mammalia and very

poor in all forms of life, and therefore by no means prominent or important
enough to form a primary region of the earth.

It may be as well here to notice what appears to be a serious objection to
making New Zealand, or any similar isolated district, one of the great
zoological regions, comparable to South America, Australia, or Ethiopia; which
is, that its claim to that distinction rests on grounds which are liable to fail. It is
because New Zealand, in addition to its negative merits, possesses three
families of birds (Apterygidæ living, Dinornithidæ and Palapterygidæ extinct),
and a peculiar lizard-like reptile, Hatteria, which has to be classed in a distinct
order, Rhynchocephalina, that the rank of a Region is claimed for it. But
supposing, what is not at all improbable, that other Rhynchocephalina should be
discovered in the interior of Australia or in New Guinea, and that Apterygidæ or
Palapterygidæ should be found to have inhabited Australia in Post-Pliocene
times, (as Dinornithidæ have already been proved to have done) the claims of
New Zealand would entirely fail, and it would be universally acknowledged to
be a part of the great Australian region. No such reversal can take place in the
case of the other regions; because they rest, not upon one or two, but upon a
large number of peculiarities, of such a nature that there is no room upon the
globe for discoveries that can seriously modify them. Even if one or two
peculiar types, like Apterygidæ or Hatteria, should permanently remain
characteristic of New Zealand alone, we can account for these by the extreme
isolation of the country, and the absence of enemies, which have enabled these
defenceless birds and reptiles to continue their existence; just as the isolation
and protection of the caverns of Carniola have enabled the Proteus to survive in
Europe. But supposing that the Proteus was the sole representative of an order
of Batrachia, and that two or three other equally curious and isolated forms
occurred with it, no one would propose that these caverns or the district
containing them, should form one of the primary divisions of the earth. Neither
can much stress be laid on the negative characteristics of New Zealand, since
they are found to an almost equal extent in every oceanic island.

Again, it is both inconvenient and misleading to pick out certain tracts from the
midst of one region or sub-region and to place them in another, on account of
certain isolated affinities which may often be accounted for by local
peculiarities. Even if the resemblance of the fauna of Chili and Patagonia to that
of the Palæarctic and Nearctic regions was much greater than it is, this mode of
dealing with it would be objectionable; but it is still more so, when we find that
these countries have a strongly marked South American character, and that the

northern affinities are altogether exceptional. The Rodentia, which comprise a
large portion of the mammalia of these countries, are wholly South American in
type, and the birds are almost all allied to forms characteristic of tropical
America.

For analogous reasons the Ethiopian must not be made to include any part of
India or Ceylon; for although the Fauna of Central India has some African
affinities, these do not preponderate; and it will not be difficult to show that to
follow Mr. Andrew Murray in uniting bodily the Ethiopian and Indian regions
of Mr. Sclater, is both unnatural and inconvenient. The resemblances between
them are of the same character as those which would unite them both with the
Palæarctic and Nearctic regions; and although it may be admitted, that, as
Professor Huxley maintains, this group forms one of the great primary divisions
of the globe, it is far too extensive and too heterogeneous to subserve the
practical uses for which we require a division of the world into zoological
regions.

Reasons for adopting the six Regions first proposed by Mr. Sclater.—So that we
do not violate any clear affinities or produce any glaring irregularities, it is a
positive, and by no means an unimportant, advantage to have our named regions
approximately equal in size, and with easily defined, and therefore easily
remembered, boundaries. All elaborate definitions of interpenetrating frontiers,
as well as regions extending over three-fourths of the land surface of the globe,
and including places which are the antipodes of each other, would be most
inconvenient, even if there were not such difference of opinion about them.
There can be little doubt, for example, that the most radical zoological division
of the earth is made by separating the Australian region from the rest; but
although it is something useful and definite to know that a group of animals is
peculiar to Australia, it is exceedingly vague and unsatisfactory to say of any
other group merely that it is extra-Australian. Neither can it be said that, from
any point of view, these two divisions are of equal importance. The next great
natural division that can be made is the separation of the Neotropical Region of
Mr. Sclater from the rest of the world. We thus have three primary divisions,
which Professor Huxley seems inclined to consider as of tolerably equal
zoological importance. But a consideration of all the facts, zoological and
palæontological, indicates, that the great northern division (Arctogæa) is fully
as much more important than either Australia or South America, as its four
component parts are less important; and if so, convenience requires us to adopt
the smaller rather than the larger divisions.

This question, of comparative importance or equivalence of value, is very
difficult to determine. It may be considered from the point of view of speciality
or isolation, or from that of richness and variety of animal forms. In isolation
and speciality, determined by what they want as well as what they possess, the
Australian and Neotropical regions are undoubtedly each comparable with the
rest of the earth (Arctogæa). But in richness and variety of forms, they are both
very much inferior, and are much more nearly comparable with the separate
regions which compose it. Taking the families of mammalia as established by
the best authors, and leaving out the Cetacea and the Bats, which are almost
universally distributed, and about whose classification there is much
uncertainty, the number of families represented in each of Mr. Sclater's regions
is as follows:

I. Palæarctic region has 31 families of terrestrial mammalia.
II. Ethiopian " " 40 " " "
III. Indian " " 31 " " "
IV. Australian " " 14 " " "
V. Neotropical " " 26 " " "
VI. Nearctic " " 23 " " "

We see, then, that even the exceedingly rich and isolated Neotropical region is
less rich and diversified in its forms of mammalian life than the very much
smaller area of the Indian region, or the temperate Palæarctic, and very much
less so than the Ethiopian region; while even the comparatively poor Nearctic
region, is nearly equal to it in the number of its family types. If these were
united they would possess fifty-five families, a number very disproportionate to
those of the remaining two. Another consideration is, that although the absence
of certain forms of life makes a region more isolated, it does not make it
zoologically more important; for we have only to suppose some five or six
families, now common to both, to become extinct either in the Ethiopian or the
Indian regions, and they would become as strongly differentiated from all other
regions as South America, while still remaining as rich in family types. In birds
exactly the same phenomenon recurs, the family types being less numerous in
South America than in either of the other tropical regions of the earth, but a
larger proportion of them are restricted to it. It will be shown further on, that the
Ethiopian and Indian, (or, as I propose to call it in this work, Oriental) regions,
are sufficiently differentiated by very important groups of animals peculiar to
each; and that, on strict zoological principles they are entitled to rank as regions

of equal value with the Neotropical and Australian. It is perhaps less clear
whether the Palæarctic should be separated from the Oriental region, with
which it has undoubtedly much in common; but there are many and powerful
reasons for keeping it distinct. There is an unmistakably different facies in the
animal forms of the two regions; and although no families of mammalia or
birds, and not many genera, are wholly confined to the Palæarctic region, a very
considerable number of both have their metropolis in it, and are very richly
represented. The distinction between the characteristic forms of life in tropical
and cold countries is, on the whole, very strongly marked in the northern
hemisphere; and to refuse to recognise this in a subdivision of the earth which is
established for the very purpose of expressing such contrasts more clearly and
concisely than by ordinary geographical terminology, would be both illogical
and inconvenient. The one question then remains, whether the Nearctic region
should be kept separate, or whether it should form part of the Palæarctic or of
the Neotropical regions. Professor Huxley and Mr. Blyth advocate the former
course; Mr. Andrew Murray (for mammalia) and Professor Newton (for birds)
think the latter would be more natural. No doubt much is to be said for both
views, but both cannot be right; and it will be shown in the latter part of this
chapter that the Nearctic region is, on the whole, fully as well defined as the
Palæarctic, by positive characters which differentiate it from both the adjacent
regions. More evidence in the same direction will be found in the Second Part
of this work, in which the extinct faunas of the several regions are discussed.

A confirmation of the general views here set forth, as to the distinctness and
approximate equivalence of the six regions, is to be found in the fact, that if any
two or more of them are combined they themselves become divisions of the
next lower rank, or "sub-regions;"—and these will be very much more
important, both zoologically and geographically, than the subdivisions of the
remaining regions. It is admitted then that these six regions are by no means of
precisely equal rank, and that some of them are far more isolated and better
characterized than others; but it is maintained that, looked at from every point
of view, they are more equal in rank than any others that can be formed; while
in geographical equality, compactness of area, and facility of definition, they are
beyond all comparison better than any others that have yet been proposed for
the purpose of facilitating the study of geographical distribution. They may be
arranged and grouped as follows, so as to exhibit their various relations and
affinities.

Neotropical Austral zone Notogæa.
Neogæa
Nearctic
Palæarctic Boreal zone
Arctogæa.
Ethiopian
Palæogæa Palæotropical zone
Oriental
Australian Austral zone Notogæa.

The above table shows the regions placed in the order followed in the Fourth
Part of this work, and the reasons for which are explained in Chapter IX. As a
matter of convenience, and for other reasons adduced in the same chapter, the
detailed exposition of the geographical distribution of the animals of the several
regions in Part III. commences with the Palæarctic and terminates with the
Nearctic region.

Objections to the system of Circumpolar Zones.—Mr. Allen's system of
"realms" founded on climatic zones (given at p. 61), having recently appeared
in an ornithological work of considerable detail and research, calls for a few
remarks. The author continually refers to the "law of the distribution of life in
circumpolar zones," as if it were one generally accepted and that admits of no
dispute. But this supposed "law" only applies to the smallest details of
distribution—to the range and increasing or decreasing numbers of species as
we pass from north to south, or the reverse; while it has little bearing on the
great features of zoological geography—the limitation of groups of genera and
families to certain areas. It is analogous to the "law of adaptation" in the
organisation of animals, by which members of various groups are suited for an
aerial, an aquatic, a desert, or an arboreal life; are herbivorous, carnivorous, or
insectivorous; are fitted to live underground, or in fresh waters, or on polar ice.
It was once thought that these adaptive peculiarities were suitable foundations
for a classification,—that whales were fishes, and bats birds; and even to this
day there are naturalists who cannot recognise the essential diversity of
structure in such groups as swifts and swallows, sun-birds and humming-birds,
under the superficial disguise caused by adaptation to a similar mode of life.
The application of Mr. Allen's principle leads to equally erroneous results, as
may be well seen by considering his separation of "the southern third of
Australia" to unite it with New Zealand as one of his secondary zoological
divisions. If there is one country in the world whose fauna is strictly
homogeneous, that country is Australia; while New Guinea on the one hand,
and New Zealand on the other, are as sharply differentiated from Australia as

any adjacent parts of the same primary zoological division can possibly be. Yet
the "law of circumpolar distribution" leads to the division of Australia by an
arbitrary east and west line, and a union of the northern two-thirds with New
Guinea, the southern third with New Zealand. Hardly less unnatural is the
supposed equivalence of South Africa (the African temperate realm) to all
tropical Africa and Asia, including Madagascar (the Indo-African tropical
realm). South Africa has, it is true, some striking peculiarities; but they are
absolutely unimportant as compared with the great and radical differences
between tropical Africa and tropical Asia. On these examples we may fairly rest
our rejection of Mr. Allen's scheme.

We must however say a few words on the zoo-geographical nomenclature
proposed in the same paper, which seems also very objectionable. The
following terms are proposed: realm, region, province, district, fauna and flora;
the first being the highest, the last the lowest and smallest sub-division.
Considering that most of these terms have been used in very different senses
already, and that no means of settling their equivalence in different parts of the
globe has been even suggested, such a complex system must lead to endless
confusion. Until the whole subject is far better known and its first principles
agreed upon, the simpler and the fewer the terms employed the better; and as
"region" was employed for the primary divisions by Mr. Sclater, eighteen years
ago, and again by Mr. Andrew Murray, in his Geographical Distribution of
Mammals; nothing but obscurity can result from each writer using some new,
and doubtfully better, term. For the sub-divisions of the regions no advantage is
gained by the use of a distinct term—"province"—which has been used (by
Swainson) for the primary divisions, and which does not itself tell you what
rank it holds; whereas the term "sub-region" speaks for itself as being
unmistakably next in subordination to region, and this clearness of meaning
gives it the preference over any independent term. As to minor named sub-
divisions, they seem at present uncalled for; and till the greater divisions are
themselves generally agreed on, it seems better to adopt no technical names for
what must, for a long time to come, be indeterminate.

Does the Arctic Fauna characterize an independent Region.—The proposal to
consider the Arctic regions as constituting one of the primary zoological
divisions of the globe, has been advocated by many naturalists. Professor
Huxley seems to consider it advisable, and Mr. Allen unhesitatingly adopts it, as
well as an "antarctic" region to balance it in the southern hemisphere. The

reason why an "Arctic Region" finds no place in this work may therefore be
here stated.

No species or group of animals can properly be classed as "arctic," which does
not exclusively inhabit or greatly preponderate in arctic lands. For the purpose
of establishing the need of an "arctic" zoological region, we should consider
chiefly such groups as are circumpolar as well as arctic; because, if they are
confined to, or greatly preponderate in, either the eastern or western
hemispheres, they can be at once allocated to the Nearctic or Palæarctic regions,
and can therefore afford no justification for establishing a new primary division
of the globe.

Thus restricted, only three genera of land mammalia are truly arctic: Gulo,
Myodes, and Rangifer. Two species of widely dispersed genera are also
exclusively arctic, Ursus maritimus and Vulpes lagopus.

Exclusively arctic birds are not much more numerous. Of land birds there are
only three genera (each consisting of but a single species), Pinicola, Nyctea, and
Surnia. Lagopus is circumpolar, but the genus has too wide an extension in the
temperate zone to be considered arctic. Among aquatic birds we have the genus
of ducks, Somateria; three genera of Uriidæ, Uria, Catarractes, and Mergulus;
and the small family Alcidæ, consisting of the genera Alca and Fratercula. Our
total then is, three genera of mammalia, three of land, and six of aquatic birds,
including one peculiar family.

In the southern hemisphere there is only the single genus Aptenodytes that can
be classed as antarctic; and even that is more properly south temperate.

In dealing with this arctic fauna we have two courses open to us; we must either
group them with the other species and genera which are common to the two
northern regions, or we must form a separate primary region for them. As a
matter of convenience the former plan seems the best; and it is that which is in
accordance with our treatment of other intermediate tracts which contain special
forms of life. The great desert zone, extending from the Atlantic shores of the
Sahara across Arabia to Central Asia, is a connecting link between the
Palæarctic, Ethiopian, and Oriental regions, and contains a number of "desert"
forms wholly or almost wholly restricted to it; but the attempt to define it as a
separate region would introduce difficulty and confusion. Neither to the "desert"

nor to the "arctic" regions could any defined limits, either geographical or
zoological, be placed; and the attempt to determine what species or genera
should be allotted to them would prove an insoluble problem. The reason
perhaps is, that both are essentially unstable, to a much greater extent than those
great masses of land with more or less defined barriers, which constitute our six
regions. The Arctic Zone has been, within a recent geological period, both
vastly more extensive and vastly less extensive than it is at present. At a not
distant epoch it extended over half of Europe and of North America. At an
earlier date it appears to have vanished altogether; since a luxuriant vegetation
of tall deciduous trees and broad-leaved evergreens flourished within ten
degrees of the Pole! The great deserts have not improbably been equally
fluctuating; hence neither the one nor the other can present that marked
individuality in their forms of life, which seems to have arisen only when
extensive tracts of land have retained some considerable stability both of
surface and climatal conditions, during periods sufficient for the development
and co-adaptation of their several assemblages of plants and animals.

We must also consider that there is no geographical difficulty in dividing the
Arctic Zone between the two northern regions. The only debateable lands,
Greenland and Iceland, are generally admitted to belong respectively to
America and Europe. Neither is there any zoological difficulty; for the land
mammalia and birds are on the whole wonderfully restricted to their respective
regions even in high latitudes; and the aquatic forms are, for our present
purpose, of much less importance. As a primary division the "Arctic region"
would be out of all proportion to the other six, whether as regards its few
peculiar types or the limited number of forms and species actually inhabiting it;
but it comes in well as a connecting link between two regions, where the
peculiar forms of both are specially modified; and is in this respect quite
analogous to the great desert zone above referred to.

I now proceed to characterize briefly the six regions adopted in the present
work, together with the sub-regions into which they may be most conveniently
and naturally divided, as shown in our general map.

Palæarctic Region.—This very extensive region comprises all temperate
Europe and Asia, from Iceland to Behring's Straits and from the Azores to
Japan. Its southern boundary is somewhat indefinite, but it seems advisable to
comprise in it all the extra-tropical part of the Sahara and Arabia, and all Persia,

Cabul, and Beloochistan to the Indus. It comes down to a little below the upper
limit of forests in the Himalayas, and includes the larger northern half of China,
not quite so far down the coast as Amoy. It has been said that this region differs
from the Oriental by negative characters only; a host of tropical families and
genera being absent, while there is little or nothing but peculiar species to
characterize it absolutely. This however is not true. The Palæarctic region is
well characterized by possessing 3 families of vertebrata peculiar to it, as well
as 35 peculiar genera of mammalia, and 57 of birds, constituting about one-third
of the total number it possesses. These are amply sufficient to characterize a
region positively; but we must also consider the absence of many important
groups of the Oriental, Ethiopian, and Nearctic regions; and we shall then find,
that taking positive and negative characters together, and making some
allowance for the necessary poverty of a temperate as compared with tropical
regions, the Palæarctic is almost as strongly marked and well defined as any
other.

Sub-divisions of the Palæarctic Region.—These are by no means so clearly
indicated as in some of the other regions, and they are adopted more for
convenience than because they are very natural or strongly marked.

The first, or European sub-region, comprises Central and Northern Europe as
far South as the Pyrenees, the Maritime and Dinaric Alps, the Balkan
mountains, the Black Sea, and the Caucasus. On the east the Caspian sea and
the Ural mountains seem the most obvious limit; but it is doubtful if they form
the actual boundary, which is perhaps better marked by the valley of the Irtish,
where a pre-glacial sea almost certainly connected the Aral and Caspian seas
with the Arctic ocean, and formed an effective barrier which must still, to some
extent, influence the distribution of animals.

The next, or Mediterranean sub-region, comprises South Europe, North Africa
with the extra-tropical portion of the Sahara, and Egypt to about the first or
second cataracts; and eastward through Asia Minor, Persia, and Cabul, to the
deserts of the Indus.

The third, or Siberian sub-region, consists of all north and central Asia north of
Herat, as far as the eastern limits of the great desert plateau of Mongolia, and
southward to about the upper limit of trees on the Himalayas.

The fourth, or Manchurian sub-region, consists of Japan and North China with
the lower valley of the Amoor; and it should probably be extended westward in
a narrow strip along the Himalayas, embracing about 1,000 or 2,000 feet of
vertical distance below the upper limit of trees, till it meets an eastern extension
of the Mediterranean sub-region a little beyond Simla. These extensions are
necessary to avoid passing from the Oriental region, which is essentially
tropical, directly to the Siberian sub-region, which has an extreme northern
character; whereas the Mediterranean and Manchurian sub-regions are more
temperate in climate. It will be found that between the upper limit of most of the
typical Oriental groups and the Thibetan or Siberian fauna, there is a zone in
which many forms occur common to temperate China. This is especially the
case among the pheasants and finches.

Ethiopian Region.—The limits of this region have been indicated by the
definition of the Palæarctic region. Besides Africa south of the tropic of Cancer,
and its islands, it comprises the southern half of Arabia.

This region has been said to be identical in the main characters of its
mammalian fauna with the Oriental region, and has therefore been united with it
by Mr. A. Murray. Most important differences have however been overlooked,
as the following summary of the peculiarities of the Ethiopian region will, I
think, show.

It possesses 22 peculiar families of vertebrates; 90 peculiar genera of
mammalia, being two-thirds of its whole number; and 179 peculiar genera of
birds, being three-fifths of all it possesses. It is further characterized by the
absence of several families and genera which range over the whole northern
hemisphere, details of which will be found in the chapter treating of the region.
There are, it is true, many points of resemblance, not to be wondered at between
two tropical regions in the same hemisphere, and which have evidently been at
one time more nearly connected, both by intervening lands and by a different
condition of the lands that even now connect them. But these resemblances only
render the differences more remarkable; since they show that there has been an
ancient and long-continued separation of the two regions, developing a distinct
fauna in each, and establishing marked specialities which the temporary
intercommunication and immigration has not sufficed to remove. The entire
absence of such wide-spread groups as bears and deer, from a country many
parts of which are well adapted to them, and in close proximity to regions where

they abound, would alone mark out the Ethiopian region as one of the primary
divisions of the earth, even if it possessed a less number than it actually does of
peculiar family and generic groups.

Sub-divisions of the Ethiopian Region.—The African continent south of the
tropic of Cancer is more homogeneous in its prominent and superficial
zoological features than most of the other regions, but there are nevertheless
important and deep-seated local peculiarities. Two portions can be marked off
as possessing many peculiar forms; the luxuriant forest district of equatorial
West Africa, and the southern extremity or Cape district. The remaining portion
has no well-marked divisions, and a large proportion of its animal forms range
over it from Nubia and Abyssinia, to Senegal on the one side and to the
Zambesi on the other; this forms our first or East-African sub-region.

The second, or West African sub-region extends along the coast from Senegal to
Angola, and inland to the sources of the Shary and the Congo.

The third, or South African sub-region, comprises the Cape Colony and Natal,
and is roughly limited by a line from Delagoa Bay to Walvish Bay.

The fourth, or Malagasy sub-region, consists of Madagascar and the adjacent
islands, from Rodriguez to the Seychelles; and this differs so remarkably from
the continent that it has been proposed to form a distinct primary region for its
reception. Its productions are indeed highly interesting; since it possesses 3
families, and 2 sub-families of mammals peculiar to itself, while almost all its
genera are peculiar. Of these a few show Oriental or Ethiopian affinities, but the
remainder are quite isolated. Turning to other classes of animals, we find that
the birds are almost as remarkable; but, as might be expected, a larger number
of genera are common to surrounding countries. More than 30 genera are
altogether peculiar, and some of these are so isolated as to require to be classed
in separate families or sub-families. The African affinity is however here more
strongly shown by the considerable number (13) of peculiar Ethiopian genera
which in Madagascar have representative species. There can be no doubt
therefore about Madagascar being more nearly related to the Ethiopian than to
any other region; but its peculiarities are so great, that, were it not for its small
size and the limited extent of its fauna, its claim to rank as a separate region
might not seem unreasonable. It is true that it is not poorer in mammals than
Australia; but that country is far more isolated, and cannot be so decidedly and

naturally associated with any other region as Madagascar can be with the
Ethiopian. It is therefore the better and more natural course to keep it as a sub-
region; the peculiarities it exhibits being of exactly the same kind as those
presented by the Antilles, by New Zealand, and even by Celebes and Ceylon,
but in a much greater degree.

Oriental Region.—On account of the numerous objections that have been made
to naming a region from the least characteristic portion of it, and not thinking
"Malayan," proposed by Mr. Blanford, a good term, (as it has a very
circumscribed and definite meaning, and especially because the "Malay"
archipelago is half of it in the Australian region,) I propose to use the word
"Oriental" instead of "Indian," as being geographically applicable to the whole
of the countries included in the region and to very few beyond it; as being
euphonious, and as being free from all confusion with terms already used in
zoological geography. I trust therefore that it may meet with general acceptance.

This small, compact, but rich and varied region, consists of all India and China
from the limits of the Palæarctic region; all the Malay peninsula and islands as
far east as Java and Baly, Borneo and the Philippine Islands; and Formosa. It is
positively characterized by possessing 12 peculiar families of vertebrata; by 55
genera of land mammalia, and 165 genera of land birds, altogether confined to
it; these peculiar genera forming in each case about one half of the total number
it possesses.

Sub-divisions of the Oriental region.—First we have the Indian sub-region,
consisting of Central India from the foot of the Himalayas in the west, and
south of the Ganges to the east, as far as a line drawn from Goa curving south
and up to the Kistna river; this is the portion which has most affinity with
Africa.

The second, or Ceylonese sub-region, consists of the southern extremity of
India with Ceylon; this is a mountainous forest region, and possesses several
peculiar forms as well as some Malayan types not found in the first sub-region.

Next we have the Indo-Chinese sub-region, comprising South China and
Burmah, extending westward along the Himalayan range to an altitude of about
9,000 or 10,000 feet, and southward to Tavoy or Tenasserim.

The last is the Indo-Malayan sub-region, comprising the Peninsula of Malacca
and the Malay Islands to Baly, Borneo, and the Philippines.

On account of the absence from the first sub-region of many of the forms most
characteristic of the other three, and the number of families and genera of
mammalia and birds which occur in it and also in Africa, it has been thought by
some naturalists that this part of India has at least an equal claim to be classed
as a part of the Ethiopian region. This question will be found fully discussed in
Chapter XII. devoted to the Oriental region, where it is shown that the African
affinity is far less than has been represented, and that in all its essential features
Central India is wholly Oriental in its fauna.

Before leaving this region a few words may be said about Lemuria, a name
proposed by Mr. Sclater for the site of a supposed submerged continent
extending from Madagascar to Ceylon and Sumatra, in which the Lemuroid
type of animals was developed. This is undoubtedly a legitimate and highly
probable supposition, and it is an example of the way in which a study of the
geographical distribution of animals may enable us to reconstruct the geography
of a bygone age. But we must not, as Mr. Blyth proposed, make this
hypothetical land one of our actual Zoological regions. It represents what was
probably a primary Zoological region in some past geological epoch; but what
that epoch was and what were the limits of the region in question, we are quite
unable to say. If we are to suppose that it comprised the whole area now
inhabited by Lemuroid animals, we must make it extend from West Africa to
Burmah, South China, and Celebes; an area which it possibly did once occupy,
but which cannot be formed into a modern Zoological region without violating
much more important affinities. If, on the other hand, we leave out all those
areas which undoubtedly belong to other regions, we reduce Lemuria to
Madagascar and its adjacent islands, which, for reasons already stated, it is not
advisable to treat as a primary Zoological region. The theory of this ancient
continent and the light it may throw on existing anomalies of distribution, will
be more fully considered in the geographical part of this work.

Australian Region.—Mr. Sclater's original name seems preferable to Professor
Huxley's, "Austral-Asian;" the inconvenience of which alteration is sufficiently
shown by the fact that Mr. Blyth proposed to use the very same term as an
appropriate substitute for the "Indian region" of Mr. Sclater. Australia is the
great central mass of the region; it is by far the richest in varied and highly

remarkable forms of life; and it therefore seems in every way fitted to give a
name to the region of which it is the essential element. The limits of this region
in the Pacific are somewhat obscure, but as so many of the Pacific Islands are
extremely poor zoologically, this is not of great importance.

Sub-divisions of the Australian Region.—The first sub-region is the Austro-
Malayan, including the islands from Celebes and Lombock on the west to the
Solomon Islands on the east. The Australian sub-region comes next, consisting
of Australia and Tasmania. The third, or Polynesian sub-region, will consist of
all the tropical Pacific Islands, and is characterized by several peculiar genera of
birds which are all allied to Australian types. The fourth, consists of New
Zealand with Auckland, Chatham, and Norfolk Islands, and must be called the
New Zealand sub-region.

The extreme peculiarities of New Zealand, due no doubt to its great isolation
and to its being the remains of a more extensive land, have induced several
naturalists to suggest that it ought justly to form a Zoological region by itself.
But the inconveniences of such a procedure have been already pointed out; and
when we look at its birds as a whole (they being the only class sufficiently well
represented to found any conclusion upon) we find that the majority of them
belong to Australian genera, and where the genera are peculiar they are most
nearly related to Australian types. The preservation in these islands of a single
representative of a unique order of reptiles, is, as before remarked, of the same
character as the preservation of the Proteus in the caverns of Carniola; and can
give the locality where it happens to have survived no claim to form a primary
Zoological region, unless supported by a tolerably varied and distinctly
characterized fauna, such as never exists in a very restricted and insular area.

Neotropical Region.—Mr. Sclater's original name for this region is preserved,
because change of nomenclature is always an evil; and neither Professor
Huxley's suggested alteration "Austro-Columbia," nor Mr. Sclater's new term
"Dendrogæa," appear to be improvements. The region is essentially a tropical
one, and the extra-tropical portion of it is not important enough to make the
name inappropriate. That proposed by Professor Huxley is not free from the
same kind of criticism, since it would imply that the region was exclusively
South American, whereas a considerable tract of North America belongs to it.
This region includes South America, the Antilles and tropical North America;

and it possesses more peculiar families of vertebrates and genera of birds and
mammalia than any other region.

Subdivisions of the Neotropical Region.—The great central mass of South
America, from the shores of Venezuela to Paraguay and Eastern Peru,
constitutes the chief division, and may be termed the Brazilian sub-region. It is
on the whole a forest country; its most remarkable forms are highly developed
arboreal types; and it exhibits all the characteristics of this rich and varied
continent in their highest development.

The second, or Chilian sub-region, consists of the open plains, pampas, and
mountains of the southern extremity of the continent; and we must include in it
the west side of the Andes as far as the limits of the forest near Payta, and the
whole of the high Andean plateaus as far as 4° of south latitude; which makes it
coincide with the range of the Camelidæ and Chinchillidæ.

The third, or Mexican sub-region, consists of Central America and Southern
Mexico, but it has no distinguishing characteristics except the absence of some
of the more highly specialized Neotropical groups. It is, however, a convenient
division as comprising the portion of the North American continent which
belongs zoologically to South America.

The fourth, or Antillean sub-region, consists of the West India islands (except
Trinidad and Tobago, which are detached portions of the continent and must be
grouped in the first sub-region); and these reproduce, in a much less marked
degree, the phenomena presented by Madagascar. Terrestrial mammals are
almost entirely wanting, but the larger islands possess three genera which are
altogether peculiar to them. The birds are of South American forms, but
comprise many peculiar genera. Terrestrial molluscs are more abundant and
varied than in any part of the globe of equal extent; and if these alone were
considered, the Antilles would constitute an important Zoological region.

Nearctic Region.—This region comprises all temperate North America and
Greenland. The arctic lands and islands beyond the limit of trees form a
transitional territory to the Palæarctic region, but even here there are some
characteristic species. The southern limit between this region and the
Neotropical is a little uncertain; but it may be drawn at about the Rio Grande del
Norte on the east coast, and a little north of Mazatlan on the west; while on the

central plateau it descends much farther south, and should perhaps include all
the open highlands of Mexico and Guatemala. This would coincide with the
range of several characteristic Nearctic genera.

Distinction of the Nearctic from the Palæarctic Region.—The Nearctic region
possesses twelve peculiar families of vertebrates or one-tenth of its whole
number. It has also twenty-four peculiar genera of mammalia and fifty-two of
birds, in each case nearly one-third of all it possesses. This proportion is very
nearly the same as in the Palæarctic region, while the number of peculiar
families of vertebrata is very much greater. It has been already seen that both
Mr. Blyth and Professor Huxley are disposed to unite this region with the
Palæarctic, while Professor Newton, in his article on birds in the new edition of
the Encyclopædia Britannica, thinks that as regards that class it can hardly claim
to be more than a sub-region of the Neotropical. These views are mutually
destructive, but it will be shown in the proper place, that on independent
grounds the Nearctic region can very properly be maintained.

Subdivisions of the Nearctic Region.—The sub-regions here depend on the great
physical features of the country, and have been in some cases accurately defined
by American naturalists. First we have the Californian sub-region, consisting of
California and Oregon—a narrow tract between the Sierra Nevada and the
Pacific, but characterized by a number of peculiar species and by several genera
found nowhere else in the region.

The second, or Rocky Mountain sub-region, consists of this great mountain
range with its plateaus, and the central plains and prairies to about 100° west
longitude, but including New Mexico and Texas in the South.

The third and most important sub-region, which may be termed the
Alleghanian, extends eastward to the Atlantic, including the Mississippi Valley,
the Alleghany Mountains, and the Eastern United States. This is an old forest
district, and contains most of the characteristic animal types of the region.

The fourth, or Canadian sub-region, comprises all the northern part of the
continent from the great lakes to the Arctic ocean; a land of pine-forests and
barren wastes, characterized by Arctic types and the absence of many of the
genera which distinguish the more southern portions of the region.

Observations on the series of Sub-regions.—The twenty-four sub-regions here
adopted were arrived at by a careful consideration of the distribution of the
more important genera, and of the materials, both zoological and geographical,
available for their determination; and it was not till they were almost finally
decided on, that they were found to be equal in number throughout all the
regions—four in each. As this uniformity is of great advantage in tabular and
diagrammatic presentations of the distribution of the several families, I decided
not to disturb it unless very strong reasons should appear for adopting a greater
or less number in any particular case. Such however have not arisen; and it is
hoped that these divisions will prove as satisfactory and useful to naturalists in
general as they have been to the author. Of course, in a detailed study of any
region much more minute sub-division may be required; but even in that case it
is believed that the sub-regions here adopted, will be found, with slight
modifications, permanently available for exhibiting general results.

I give here a table showing the proportionate richness and speciality of each
region as determined by its families of vertebrates and genera of mammalia and
birds; and also a general table of the regions and sub-regions, arranged in the
order that seems best to show their mutual relations.

Comparative Richness of the Six Regions.

Vertebrata. Mammalia. Birds.
Regions. Families. Peculiar Genera. Peculiar Per Genera. Peculiar Per
families. genera. centage. genera. centage.

Palæarctic 136 3 100 35 35 174 57 33
Ethiopian 174 22 140 90 64 294 179 60
Oriental 164 12 118 55 46 340 165 48
Australian 141 30 72 44 61 298 189 64
Neotropical 168 44 130 103 79 683 576 86
Nearctic 122 12 74 24 32 169 52 31

Table of Regions and Sub-regions.

Regions. Sub-regions. Remarks.

I. Palæarctic 1. North Europe.
2. Mediterranean (or S. Eu.) Transition to Ethiopian.
3. Siberia. Transition to Nearctic.
4. Manchuria (or Japan) Transition to Oriental.

II. Ethiopian 1. East Africa. Transition to Palæarctic.
2. West Africa.
3. South Africa.
4. Madagascar.

III. Oriental 1. Hindostan (or Central Ind.) Transition to Ethiopian.
2. Ceylon.
3. Indo-China (or Himalayas) Transition to Palæarctic.
4. Indo-Malaya. Transition to Australian.

IV. Australian 1. Austro-Malaya. Transition to Oriental.
2. Australia.
3. Polynesia.
4. New Zealand. Transition to Neotropical.

V. Neotropical 1. Chili (or S. Temp. Am.) Transition to Australian.
2. Brazil.
3. Mexico (or Trop. N. Am.) Transition to Nearctic.
4. Antilles.

VI. Nearctic 1. California.
2. Rocky Mountains. Transition to Neotropical.
3. Alleghanies (or East U. S.)
4. Canada. Transition to Palæarctic.

CHAPTER V.

C L A S S I F I C AT I O N A S A F F E C T I N G T H E S T U D Y O F G E O G R A P H I C A L
DISTRIBUTION.

A little consideration will convince us, that no inquiry into the causes and laws
which determine the geographical distribution of animals or plants can lead to
satisfactory results, unless we have a tolerably accurate knowledge of the
affinities of the several species, genera, and families to each other; in other
words, we require a natural classification to work upon. Let us, for example,
take three animals—a, b, and c—which have a general external resemblance to
each other, and are usually considered to be really allied; and let us suppose that
a and b inhabit the same or adjacent districts, while c is found far away on the
other side of the globe, with no animals at all resembling it in any of the
intervening countries. We should here have a difficult problem to solve; for we
should have to show that the general laws by which we account for the main
features of distribution, will explain this exceptional case. But now, suppose
some comparative anatomist takes these animals in hand, and finds that the
resemblance of c to a and b is only superficial, while their internal structure
exhibits marked and important differences; and that c really belongs to another
group of animals, d, which inhabits the very region in which c was found—and
we should no longer have anything to explain. This is no imaginary case. Up to
a very few years ago a curious Mexican animal, Bassaris astuta, was almost
always classed in the civet family (Viverridæ), a group entirely confined to
Africa and Asia; but it has now been conclusively shown by Professor Flower
that its real affinities are with the racoons (Procyonidæ), a group confined to
North and South America. In another case, however, an equally careful
examination shows, that an animal peculiar to the Himalayas (Ælurus fulgens)
has its nearest ally in the Cercoleptes of South America. Here, therefore, the
geographical difficulty really exists, and any satisfactory theory of the causes
that have led to the existing distribution of living things, must be able to
account, more or less definitely, for this and other anomalies. From these cases
it will be evident, that if any class or order of animals is very imperfectly known
and its classification altogether artificial, it is useless to attempt to account for
the anomalies its distribution may present; since those anomalies may be, to a
great extent, due to false notions as to the affinities of its component species.

According to the laws and causes of distribution discussed in the preceding
chapters, we should find limited and defined distribution to be the rule,

universal or indefinite distribution to be the exception, in every natural group
corresponding to what are usually regarded as families and genera; and so much
is this the case in nature, that when we find a group of this nominal rank
scattered as it were at random over the earth, we have a strong presumption that
it is not natural; but is, to a considerable extent, a haphazard collection of
species. Of course this reasoning will only apply, in cases where there are no
unusual means of dispersal, nor any exceptional causes which might determine
a scattered distribution.

From the considerations now adduced it becomes evident, that it is of the first
importance for the success of our inquiry to secure a natural classification of
animals, especially as regards the families and genera. The higher groups, such
as classes and orders, are of less importance for our purpose; because they are
almost always widely and often universally distributed, except those which are
so small as to be evidently the nearly extinct representatives of a once more
extensive series of forms. We now proceed to explain the classification to be
adopted, as low down as the series of families. To these, equivalent English
names are given wherever they exist, in order that readers possessing no
technical knowledge, may form some conception of the meaning of the term
"family" in zoology.

The primary divisions of the animal kingdom according to two eminent modern
authorities are as follows:

Huxley. Carus and Gerstaeker.
Classification of Animals (1869). Handbuch der Zoologie (1868).

1. Protozoa
1. Protozoa.
2. Infusoria
3. Cœlenterata 2. Cœlenterata.
4. Annuloida 3. Echinodermata.
4. Vermes.
5. Annulosa
5. Arthropoda.
6. Molluscoida 6. Molluscoida.
7. Mollusca 7. Mollusca.
8. Vertebrata 8. Vertebrata.

For reasons already stated it is only with the fifth, seventh, and eighth of these
groups that the present work proposes to deal; and even with the fifth and
seventh only partially and in the most general way.

The classes of the vertebrata, according to both the authors above quoted, are: 1.
Mammalia. 2. Aves. 3. Reptilia. 4. Amphibia. 5. Pisces, in which order they will
be taken here.

The sub-classes and orders of mammalia are as follows:

MAMMALIA.

Huxley (1869), Flower (1870). Carus (1868).

1. Primates.
1. Primates 5. Prosimii.
2. Chiroptera 2. Chiroptera.
3. Insectivora 3. Insectivora.
6. Carnivora
4. Carnivora 7. Pinnipedia.
5. Cetacea
Monodelphia 6. Sirenia 12. Natantia.
10. Artiodactyla.
7. Ungulata 11. Perissodactyla.
8. Proboscidea 9. Proboscidea.
9. Hyracoidea 8. Lamnungia.
10. Rodentia 4. Rodentia.
11. Edentata 13. Bruta.
Didelphia 12. Marsupialia 14. Marsupialia.
Ornithodelphia 13. Monotremata 15. Monotremata.

The above series of orders is arranged according to Professor Flower's
Osteology of Mammalia, and they will follow in this succession throughout my
work. Professor Huxley arranges the same orders in a different series.

In determining the manner in which the several orders shall be subdivided into
families, I have been guided in my choice of classifications mainly by the
degree of attention the author appears to have paid to the group, and his known
ability as a systematic zoologist; and in a less degree by considerations of
convenience as regards the special purposes of geographical distribution. In
many cases it is a matter of great doubt whether a certain group should form
several distinct families or be united into one or two; but one method may bring
out the peculiarities of distribution much better than the other, and this is, in our
case, a sufficient reason for adopting it.

For the Primates I follow, with some modifications, the classification of Mr. St.
George Mivart given in his article "Apes" in the new edition of the
Encyclopædia Britannica, and in his paper in the Proceedings of the Zoological
Society of London, 1865, p. 547. It is as follows:

Order—PRIMATES, divided into two Sub-orders:
I. Anthropoidea.
II. Lemuroidea.

Sub-order—Anthropoidea.
Fam.
Hominidæ Man.
1. Simiidæ Anthropoid Apes.
Simii 2. Semnopithecidæ Old-world Monkeys.
3. Cynopithecidæ Baboons and Macaques.
4. Cebidæ American Monkeys.
Cebii
5. Hapalidæ Marmosets.

Sub-order—Lemuroidea.
Fam.
6. Lemuridæ Lemurs.
7. Tarsiidæ Tarsiers.
8. Chiromyidæ Aye-ayes.

Omitting man (for reasons stated in the preface) the three first families are
considered by Professor Mivart to be sub-families of Simiidæ; but as the
geographical distribution of the Old World apes is especially interesting, it is

thought better to treat them as families, a rank which is claimed for the
anthropoid apes by many naturalists.

As no good systematic work on the genera and species of bats has been yet
published, I adopt the five families as generally used in this country, with the
genera as given in the papers of Dr. J. E. Gray and Mr. Tomes. A monograph by
Dr. Peters has long been promised, and his outline arrangement was published
in 1865, but this will perhaps be materially altered when the work appears.

Order—CHIROPTERA.

Fam.
Frugivora 9. Pteropidæ Fruit-eating
Bats.
10. Phyllostomidæ Leaf-nosed
Bats.
Istiophora
11. Rhinolophidæ Horse-shoe
Insectivora Bats.
12. Vespertilionidæ True Bats.
Gymnorhini 13. Noctilionidæ Dog-headed
Bats.

The genera of Chiroptera are in a state of great confusion, the names used by
different authors being often not at all comparable, so that the few details given
of the distribution of the bats are not trustworthy. We have therefore made little
use of this order in the theoretical part of the work.

The osteology of the Insectivora has been very carefully worked out by
Professor Mivart in the Jounral of Anatomy and Physiology (Vol. ii., p. 380),
and I follow his classification as given there, and in the Proceedings of the
Zoological Society (1871).

Order—INSECTIVORA.

Fam.
14. Galeopithecidæ Flying Lemurs.

15. Macroscelididæ Elephant Shrews.
16. Tupaiidæ Squirrel Shrews.
17. Erinaceidæ Hedgehogs.
18. Centetidæ Tenrecs.
19. Potamogalidæ Otter Shrew.
20. Chrysochloridæ Golden Moles.
21. Talpidæ Moles.
22. Soricidæ Shrews.

The next order, Carnivora, has been studied in detail by Professor Flower; and I
adopt the classification given by him in the Proceedings of the Zoological
Society, 1869, p. 4.

Order—CARNIVORA.

Fam.
23. Felidæ Cats, Lion, &c.
24. Cryptoproctidæ Cryptoprocta.
Æluroidea 25. Viverridæ Civets.
26. Protelidæ Aard-wolf.
27. Hyænidæ Hyænas.
Fissipedia Cynoidea 28. Canidæ Dogs, Foxes, &c.
29. Mustelidæ Weasels.
30. Procyonidæ Racoons.
Arctoidea
31. Æluridæ Pandas.
32. Ursidæ Bears.
33. Otariidæ Eared Seals.
Pinnipedia 34. Trichechidæ Walrus.
35. Phocidæ Seals.

The Cetacea is one of those orders the classification of which is very unsettled.
The animals comprising it are so huge, and there is so much difficulty in
preserving them, that only a very few species are known with anything like
completeness. A considerable number of genera and species have been
described or indicated; but as many of these are founded on imperfect

specimens of perhaps a single individual, it is not to be wondered at that those
few naturalists who occupy themselves with the study of these large animals,
cannot agree as to the proper mode of grouping them into natural families. They
are, however, of but little importance to us, as almost all the species inhabit the
ocean, and of only a few of them can it be said that anything is accurately
known of their distribution. I therefore consider it best to follow Professor
Carus, who makes a smaller number of families; but I give also the arrangement
of Dr. Gray in his British Museum catalogue of whales and seals, as modified
subsequently in the Proceedings of Zoological Society, 1870, p. 772. The
Zeuglodontidæ, a family of extinct tertiary whales, are classed by Professors
Owen and Carus between Cetacea and Sirenia, while Professor Huxley
considers them to have been carnivorous and allied to the seals.

Order—CETACEA.

Fam. (Carus). Fam. (Gray).
Sub-order I.— Balænidæ 36. Balænidæ.
Mystaceti. Balænopteridæ 37. Balænopteridæ.
Catodontidæ 38. Catodontidæ.
Hyperoodontidæ.
Hyperoodontidæ 39. Epiodontidæ.
Xiphiadæ.
Sub-order II.—
Odontoceti. Monodontidæ 40. (Part of Delphinidæ.)
Platanistidæ.
Iniadæ.
Delphinidæ.
Delphinidæ 41. Globiocephalidæ.
Orcadæ.
Belugidæ.
Pontoporiadæ.
Extinct family Zeuglodontidæ.

Order—SIRENIA.

The order Sirenia, comprising the sea-cows, consists of a single family:

Family 42. Manatidæ.

The extensive order Ungulata comprises the three orders Pachydermata,
Solidungula, and Ruminantia of the older naturalists. The following
classification is that now generally adopted, the only difference of opinion
being as to whether some of the groups should be classed as families or sub-
families, a matter of little importance for our purpose:

Order—UNGULATA.

Fam.
43. Equidæ Horses.
Perissodactyla or
44. Tapiridæ Tapirs.
Odd-toed
45. Rhinoceros.
Ungulates
Rhinocerotidæ
46. Hippopotamus.
Suina Hippopotamidæ
47. Suidæ Swine.
Tylopoda 48. Camelidæ Camels.
Artiodactyla or
Tragulina 49. Tragulidæ Chevrotains.
Even-toed
50. Cervidæ Deer.
Ungulates
51. Giraffes.
Pecora Camelopardidæ
52. Bovidæ Cattle, Sheep,
Antelopes, &c.

The two next orders consist of but a single family each, viz.:

Order Fam.
PROBOSCIDEA 53. Elephantidæ Elephants.
HYRACOIDEA 54. Hyracidæ Rock-rabbits.

We now come to the Rodentia, a very extensive and difficult order, in which
there is still much difference of opinion as to the details of classification,
although the main outlines are pretty well settled. The foundations of a true

classification of this order were laid by Mr. G. R. Waterhouse more than thirty
years ago, and succeeding authors have done little more than follow his
arrangement with unimportant modifications. Professor Lilljeborg, of Upsala,
has however made a special study of this group of animals, and has given an
original and detailed classification of all the genera. (Systematisk Öfversigt af de
Gnagande Däggdjuren, Glires. Upsala, 1866.) I follow this arrangement with a
few slight modifications suggested by other naturalists, and which make it
better adapted for the purposes of this work.

Order—RODENTIA.

Fam.
55. Muridæ Rats.
56. Spalacidæ Mole-rats.
57. Dipodidæ Jerboas.
58. Myoxidæ Dormice.
Murina 59. Saccomyidæ Pouched
(Waterhouse) Rats.
60. Castoridæ Beavers.
61. Sciuridæ Squirrels.
62. Sewellels.
Simplicidentati
Haploodontidæ
63. Chinchillidæ Chinchillas.
64. Octodontidæ Octodons.
65. Echimyidæ Spiny Rats.
Hystricina
66. Cercolabidæ Tree
(Waterhouse)
Porcupines
67. Hystricidæ Porcupines.
68. Caviidæ Cavies.
Leporina 69. Lagomyidæ Pikas.
Duplicidentati
(Waterhouse) 70. Leporidæ Hares.

The Edentata have been classified by Mr. Turner, in the Proceedings of the
Zoological Society (1851, p. 205), by Dr. Gray in the British Museum
Catalogue, and by Professor Carus in his Handbuch. The former takes a middle
course between the numerous families of Dr. Gray, seven in number, and the

two families to which Professor Carus restricts the existing species. I therefore
follow Mr. Turner.

Order—EDENTATA.

Fam.
Bradypoda 71. Bradypodidæ Sloths.
72. Manididæ Scaly Ant-eaters.
73. Dasypodidæ Armadillos.
Entomophaga
74. Orycteropodidæ Ant-bears.
75. Myrmecophagidæ Ant-eaters.

The Marsupials have been well classified and described by Mr. Waterhouse in
the first volume of his Natural History of Mammalia, and his arrangement is
here followed. The suborders adopted by Professor Carus are also given.

Order—MARSUPIALIA.

Fam.
76. Didelphidæ Opossums.
77. Dasyuridæ Native Cats.
Rapacia (Wagner)
78. Myrmecobiidæ Native Ant-eater.
79. Peramelidæ Bandicoots.
Poephaga (Owen) 80. Macropodidæ Kangaroos.
Carpophaga (Owen) 81. Phalangistidæ Phalangers.
Rhizophaga (Owen) 82. Phascolomyidæ Wombats.

Order—MONOTREMATA.

The last order, the Monotremata, consist of two families, which Professor Carus
combines into one, but which it seems more natural to keep separate.

Fam.

83. Ornithorhynchidæ Duckbill.
84. Echidnidæ Echidna.

BIRDS.

Birds are perhaps the most difficult to classify of all the divisions of the
vertebrata. The species and genera are exceedingly numerous, and there is such
a great uniformity in general structure and even in the details of external form,
that it is exceedingly difficult to find characters by which orders and families
can be characterised. For a long time the system of Vigors and Swainson was
followed; but this wholly ignored anatomical characters and in many cases
plainly violated well-marked affinities. Characters derived from the form of the
sternum, the scutellation of the tarsi, and the arrangement of the feathers, have
all assisted in determining natural groups. More recently Professor Huxley has
applied the variations of the bony palate to the general arrangement of birds;
and still more recently Professor Garrod has studied certain leg-muscles for the
same purpose. The condition of the young as regards plumage, and even the
form, texture, and coloration of the egg, have also been applied to solve
doubtful cases of affinity; yet the problem is not settled, and it will probably
remain for another generation of ornithologists to determine with any approach
to accuracy what are the most natural divisions of the class into orders and
families. In a work like the present it is evidently not advisable to adopt all the
recent classifications; since experience has shown that no arrangement in which
one set of characters is mainly relied on, long holds its ground. Such
modifications of the old system as seem to be well established will be adopted;
but the older groups will be adhered to in cases where the most recent
classifications are open to doubt, or seem inconvenient as separating families,
which, owing to their similarity in general structure, form and habits are best
kept together for the purposes of geographical distribution.

The old plan of putting the birds of prey at the head of the class, is now almost
wholly given up; both because they are not the most highly organised, but only
one of the most specialised forms of birds, and because their affinities are not
with the Passeres, but rather with the cormorants and some other of the aquatic
groups. The Passeres therefore are placed first; and the series of families is
begun by the thrushes, which are certainly the most typical and generally well-
organised form of birds. Instead of the Scansores and Fissirostres of the older
authors, the order Picariæ, which includes them both, is adopted, but with some

reluctance; as the former are, generally speaking, well marked and strongly
contrasted groups, although certain families have been shown to be
intermediate. In the Picariæ are included the goat-suckers, swifts, and
humming-birds, sometimes separated as a distinct order, Macrochires. The
parrots and the pigeons form each a separate order. The old groups of Grallæ
and Anseres are preserved, as more convenient than breaking them up into
widely separated parts; for though the latter plan may in some cases more
strictly represent their affinities, its details are not yet established, nor is it much
used by ornithologists. In accordance with these views the following is the
series of orders and families of birds adopted in this work:

Class—AVES.

Orders.
Including the great mass of the smaller birds—
1. Crows,
Passeres Finches, Flycatchers, Creepers, Honeysuckers,
&c., &c.
Including Woodpeckers, Cuckoos, Toucans,
2. Picariæ Kingfishers,
Swifts, &c., &c.
3. Psittaci Parrots only.
4. Columbæ Pigeons and the Dodo.
5. Gallinæ Grouse, Pheasants, Curassows, Mound-builders, &c.
6. Opisthocomi The Hoazin only.
7. Accipitres Eagles, Owls, and Vultures.
8. Grallæ Herons, Plovers, Rails, &c.
9. Anseres Gulls, Ducks, Divers, &c.
10. Struthiones Ostrich, Cassowary, Apteryx, &c.

The Passeres consist of fifty families, which may be arranged and grouped in
series as follows. It must however be remembered that the first family in each
series is not always that which is most allied to the last family of the preceding
series. All extensive natural groups consist of divergent or branching alliances,
which renders it impossible to arrange the whole in one continuous series.

A.—Typical or Turdoid Passeres.
1. Turdidæ Thrushes.
2. Sylviidæ Warblers.
3. Timaliidæ Babblers.
4. Panuridæ Reedlings.
5. Cinclidæ Dippers.
6. Troglodytidæ Wrens.
7. Chamæidæ
8. Certhiidæ Creepers.
9. Sittidæ Nuthatches.
10. Paridæ Tits.
11. Liotrichidæ Hill-tits.
12. Phyllornithidæ Green Bulbuls.
13. Pycnonotidæ Bulbuls.
14. Oriolidæ Orioles.
15. Campephagidæ Caterpillar-shrikes.
16. Dicruridæ Drougos.
17. Muscicapidæ Flycatchers.
18. Pachycephalidæ Thick-heads.
19. Laniidæ Shrikes.
20. Corvidæ Crows.
21. Paradiseidæ Paradise-birds.
22. Meliphagidæ Honey-suckers.
23. Nectarineidæ Sun-birds.

B.—Tanagroid Passeres.
24. Dicæidæ Flower-peckers.
25. Drepanididæ
26. Cærebidæ Sugar-birds.
27. Mniotiltidæ Wood-warblers.
28. Vireonidæ Greenlets.
29. Ampelidæ Waxwings.
30. Hirundinidæ Swallows.
31. Icteridæ Hangnests.
32. Tanagridæ Tanagers.
33. Fringillidæ Finches.

C.—Sturnoid Passeres.

34. Ploceidæ Weaver-birds.
35. Sturnidæ Starlings.
36. Artamidæ Swallow-shrikes.
37. Alaudidæ Larks.
38. Motacillidæ Wagtails.

D.—Formicaroid Passeres.
39. Tyrannidæ Tyrants.
40. Pipridæ Manakins.
41. Cotingidæ Chatterers.
42. Phytotomidæ Plant-cutters.
43. Eurylæmidæ Broad-bills.
44. Dendrocolaptidæ American Creepers.
45. Formicariidæ Ant-thrushes.
46. Pteroptochidæ
47. Pittidæ Pittas.
48. Paictidæ

E.—Anomalous Passeres.
49. Menuridæ Lyre-birds.
50. Atrichidæ Scrub-birds.

The preceding arrangement is a modification of that proposed by myself in the
Ibis (1874, p. 406). The principal alterations are adding the families Panuridæ
and Sittidæ in series A, commencing series B with Dicæidæ; bringing
Vireonidæ next to the allied American family Mniotiltidæ; and placing
Motacillidæ in series C next to Alaudidæ. At the suggestion of Professor
Newton I place Menuridæ and Atrichidæ apart from the other Passeres, as they
both possess striking peculiarities of anatomical structure.

The heterogeneous families constituting the order Picariæ may be conveniently
arranged as follows:

51. Picidæ Woodpeckers.
52. Yungidæ Wrynecks.
53. Indicatoridæ Honey-guides.
Sub-order— 54. Megalæmidæ Barbets.
Scansores. 55. Rhamphastidæ Toucans.
56. Musophagidæ Plantain-eaters.
57. Coliidæ Colies.
58. Cuculidæ Cuckoos.
Intermediate 59. Leptosomidæ The Leptosoma.
60. Bucconidæ Puff-birds.
61. Galbulidæ Jacamars.
62. Coraciidæ Rollers.
63. Meropidæ Bee-eaters.
64. Todidæ Todies.
65. Momotidæ Motmots.
66. Trogonidæ Trogons.
Sub-order— 67. Alcedinidæ Kingfishers.
Fissirostres. 68. Bucerotidæ Hornbills.
69. Upupidæ Hoopoes.
70. Irrisoridæ Promerops.
71. Podargidæ Frog-mouths.
72. Steatornithidæ The Guacharo.
73. Caprimulgidæ Goatsuckers.
74. Cypselidæ Swifts.
75. Trochilidæ Humming-birds.

The Psittaci or parrot tribe are still in a very unsettled state of classification; that
recently proposed by Professor Garrod differing widely from the arrangement
adopted in Dr. Finsch's monograph of the order. Taking advantage of the
researches of these and other authors, the following families are adopted as the
most convenient in the present state of our knowledge:

76. Cacatuidæ The Cockatoos.
77. Platycercidæ The Broad-tailed Paroquets of Australia.
78. Palæornithidæ The Oriental Parrots and Paroquets.

79. Trichoglossidæ The Brush-tongued Paroquets and Lories.
80. Conuridæ The Macaws and their allies.
81. Psittacidæ The African and South American Parrots.
82. Nestoridæ The Nestors of New Zealand.
83. Stringopidæ The Owl-parrots of New Zealand.

The Columbæ, or pigeons, are also in a very unsatisfactory state as regards a
natural classification. The families, sub-families, and genera proposed by
various authors are very numerous, and often quite irreconcilable. I therefore
adopt only two families; and generally follow Mr. G. R. Gray's hand-list for the
genera, except where trustworthy authorities exist for a different arrangement.
The families are:

84. Columbidæ Pigeons and Doves.
85. Dididæ The extinct Dodo and allies.

The Gallinæ, or game-birds, may be divided into seven families:

Fam. Sub-fam.
86. Pteroclidæ Sand-grouse
87. Tetraonidæ Partridges and Grouse.
Pavoninæ Peafowl.
Lophophorinæ Tragopans, &c.
Phasianinæ Pheasants.
88. Phasianidæ Euplocaminæ Fire-backed Pheasants, &c.
Gallinæ Jungle-fowl.
Meleagrinæ Turkeys.
Numidinæ Guinea-fowl.
89. Turnicidæ Hemipodes.
90. Megapodiidæ Mound-makers.
Cracinæ Curassows.
91. Cracidæ Penelopinæ Guans.
Oreophasinæ Mountain-pheasant.
92. Tinamidæ Tinamous.

The Opisthocomi consist of one family containing a single species, the
"Hoatzin" of Guiana.

Family 93. Opisthocomidæ.

The Accipitres, or birds of prey, which were long considered to be the highest
and most perfect order of birds, are now properly placed lower down in the
series, their affinities being more with the aquatic than with the perching birds.
The following is the arrangement adopted by Mr. Sharpe in his recently
published British Museum catalogue of diurnal birds of prey:—

Sub-orders. Fam. Sub-families.
Vulturinæ Vultures.
94. Vulturidæ
Sarcorhamphinæ Turkey-buzzards.
95. Serpentariidæ
Falcones Polyborniæ Caracaras.
Accipitrinæ Hawks.
96. Falconidæ Buteoninæ Buzzards.
Aquilinæ Eagles.
Falconinæ Falcons.
Pandiones 97. Pandionidæ Fishing-eagles.
Striges 98. Strigidæ Owls.

The Grallæ or Grallatores are in a very unsettled state. The following series of
families is in accordance with the views of some of the best modern
ornithologists:

99. Rallidæ Rails, &c.
100. Scolopacidæ Sandpipers and Snipes
101. Chionididæ Sheath-bills.
102. Thinocoridæ Quail-snipes.
103. Parridæ Jacanas.
104. Glareolidæ Pratincoles.
105. Charadriidæ Plovers.
106. Otididæ Bustards.

107. Gruidæ Cranes.
108. Cariamidæ Cariamas.
109. Aramidæ Guaraunas.
110. Psophiidæ Trumpeters.
111. Eurypygidæ Sun-bitterns.
112. Rhinochœtidæ Kagus.
113. Ardeidæ Herons.
114. Plataleidæ Spoonbills and Ibis.
115. Ciconiidæ Storks.
116. Palamedeidæ Screamers.
117. Phænicopteridæ Flamingoes.

The Anseres or Natatores are almost equally unsettled. The flamingoes are
usually placed in this order, but their habits best assort with those of the waders.

Fam.
118. Anatidæ Duck and Geese.
119. Laridæ Gulls.
120. Procellariidæ Petrels.
121. Pelecanidæ Pelicans.
122. Spheniscidæ Penguins.
123. Colymbidæ Divers.
124. Podicipidæ Grebes.
125. Alcidæ Auks.

The last order of birds is the Struthiones or Ratitæ, considered by many
naturalists to form a distinct sub-class. It consists of comparatively few species,
either living or recently extinct.

126. Struthionidæ Ostriches.
Living 127. Casuariidæ Cassowaries.
128. Apterygidæ Apteryx.
129. Dinornithidæ Dinornis.
Extinct 130. Palapterygidæ Palapteryx.
131. Æpyornithidæ Æpyornis.

REPTILES.

In reptiles I follow the classification of Dr. Günther as given in the
Philosophical Transactions, vol. clvii., p. 625. He divides the class into five
orders as follows:—

Sub-classes. Orders.
1. Ophidia Serpents.
I. Squamata 2. Lacertilia Lizards.
3. Rhyncocephalina The Hatteria.
II. Loricata 4. Crocodilia Crocodiles.
III. Cataphracta 5. Chelonia Tortoises.

In the arrangement of the families comprised in each of these orders I also
follow the arrangement of Dr. Günther and Dr. J. E. Gray, as given in the British
Museum Catalogue, or as modified by the former gentleman who has kindly
given me much personal information.

The Ophidia, or Snakes, form the first order and are classified as follows:—

Fam.

1. Typhlopidæ
2. Tortricidæ
Burrowing Snakes.
3. Xenopeltidæ
4. Uropeltidæ
5. Calamaridæ Dwarf ground-snakes.
6. Oligodontidæ.
7. Colubridæ Colubrine Snakes.
8. Homalopsidæ Fresh-water Snakes.
9. Psammophidæ Desert-snakes.
Innocuous Snakes 10. Rachiodontidæ.
11. Dendrophidæ Tree-snakes.
12. Dryiophidæ Whip-snakes.
13. Dipsasidæ Nocturnal tree-snakes.
14. Scytalidæ
15. Lycodontidæ Fanged ground-snakes.
16. Amblycephalidæ Blunt-heads.
17. Pythonidæ Pythons.
18. Erycidæ Sand-snakes.
19. Acrochordidæ Wart-snakes.

20. Elapidæ Cobras, &c.
Venomous Colubrine 21. Dendraspididæ.
Snakes 22. Atractaspididæ.
23. Hydrophidæ Sea-snakes.

24. Crotalidæ Pit-vipers.
Viperine Snakes
25. Viperidæ True vipers.

The second order, Lacertilia, are arranged as follows:—

Fam.

26. Trogonophidæ
27. Chirotidæ
Amphisbænians.
28. Amphisbænidæ
29. Lepidosternidæ
30. Varanidæ Water Lizards.
31. Helodermidæ.
32. Teidæ Teguexins.
33. Lacertidæ
Land Lizards.
34. Zonuridæ
35. Chalcidæ.
36. Anadiadæ.
37. Chirocolidæ.
38. Iphisadæ.
39. Cercosauridæ.
40. Chamæsauridæ.
41. Gymnopthalmidæ Gape-eyed Scinks.
42. Pygopodidæ Two-legged Lizards.
43. Aprasiadæ.
44. Lialidæ.
45. Scincidæ Scinks.
46. Ophiomoridæ Snake-lizards.
47. Sepidæ Sand-lizards.
48. Acontiadæ.
49. Geckotidæ Geckoes.
50. Iguanidæ Iguanas.
51. Agamidæ Fringed Lizards.
52. Chameleonidæ Chameleons.

The third order, Rhyncocephalina consists of a single family:—

53. Rhyncocephalidæ The Hatteria of New Zealand.

The fourth order, Crocodilia or Loricata, consists of three families:—

54. Gavialidæ Gavials.
55. Crocodilidæ Crocodiles.
56. Alligatoridæ Alligators.

The fifth order, Chelonia, consists of four families:—

57. Testudinidæ Land and fresh-water Tortoises.
58. Chelydidæ Fresh-water Turtles.
59. Trionychidæ Soft Turtles.
60. Cheloniidæ Sea Turtles.

AMPHIBIA.

In the Amphibia I follow the classification of Professor Mivart, as given for a
large part of the order in the Proceedings of the Zoological Society for 1869.
For the remainder I follow Dr. Strauch, Dr. Günther, and a MSS. arrangement
kindly furnished me by Professor Mivart.

The class is first divided into three groups or orders, and then into families as
follows:—

Order I.—PSEUDOPHIDIA.

Fam.
1. Cæciliadæ Cæcilia.

Order II.—BATRACHIA URODELA.

2. Sirenidæ Siren.
3. Proteidæ Proteus.
4. Amphiumidæ Amphiuma.
5. Menopomidæ Giant Salamanders.
6. Salamandridæ Salamanders and Newts.

Order III.—BATRACHIA ANOURA.

7. 16. Pelodryadæ
Rhinophrynidæ
Tree
8. Phryniscidæ 17. Hylidæ
Frogs.
9. Hylaplesidæ 18.
Toads. Polypedatidæ
10. Bufonidæ 19. Ranidæ
11. Xenorhinidæ 20. Frogs.
Discoglossidæ
12. Engystomidæ 21. Pipidæ
Tongueless
13. 22.
Toads.
Bombinatoridæ Dactylethridæ
14. Frogs.
Plectromantidæ
15. Alytidæ

FISHES.

These are arranged according to the classification of Dr. Günther, whose great
work "The British Museum Catalogue of Fishes," has furnished almost all the
material for our account of the distribution of the class.

In that work all existing fishes are arranged in six sub-classes and thirteen
orders. A study of the extraordinary Ceratodus from Australia has induced Dr.
Günther to unite three of his sub-classes; but as his catalogue will long remain a
handbook for every student of fishes, it seems better to follow the arrangement
there given, indicating his later views by bracketing together the groups he now
thinks should be united.

Sub-class. Order. Families. Remarks.

1. 47 Gasterosteidæ
Acanthopterygii to Notacanthi.
2. Do. 5 Pomacentridæ
Pharyncognathi to Chromidæ.
3. Acanthini 6 Gadopsidæ to
Pleuronectidæ.
4. Physostomi 29 Siluridæ to
Teleostei
Pegasidæ.
5. 2 Solenostomidæ
Lophobranchii and
Syngnathidæ.
6. Plectognathi 2 Sclerodermi
Ganoidei and
Gymnodontes.
Dipnoi 7. Sirenoidei 1 Sirenoidei.
8. Holostei 3 Amiidæ to
Lepidosteidæ.
Ganoidei 9. Chondrostei 2 Accipenseridæ
and
Polydontidæ.
10. Holocephala 1 Chimæridæ.
Chondropterygii 11. 15 Carchariidæ to
Plagiostomata Myliobatidæ.
Cyclostomata 12. 2 Petromyzontidæ
Marsipobranchii and Myxinidæ.
Leptocardii 13. Cirrhostomi 1 Cirrhostomi.
Total 116 families.

INSECTS.

The families and genera of insects are so immensely numerous, probably
exceeding fifty-fold those of all other land animals, that for this cause alone it
would be impossible to enter fully into their distribution. It is also quite
unnecessary, because many of the groups are so liable to be transported by
accidental causes, that they afford no useful information for our subject; while
others are so obscure and uninteresting that they have been very partially collected

and studied, and are for this reason equally ineligible. I have therefore selected a
few of the largest and most conspicuous families, which have been so assiduously
collected in every part of the globe, and so carefully studied at home, as to afford
valuable materials for comparison with the vertebrate groups, when we have made
due allowance for the dependence of many insects on peculiar forms of vegetation,
and the facility with which many of them are transported either in the egg, larva, or
perfect state, by winds, currents, and other less known means.

I confine myself then, almost exclusively, to the sixteen families of Diurnal
Lepidoptera or butterflies, and to six of the most extensive, conspicuous, and
popular families of Coleoptera. The number of species of Butterflies is about the
same as that of Birds, while the six families of Coleoptera selected, comprise more
than twenty thousand species, far exceeding the number of all other vertebrates.
These families have all been recently catalogued, so that we have very complete
information as to their arrangement and distribution.

LEPIDOPTERA DIURNA, OR BUTTERFLIES.

Fam. Fam.
1. Danaidæ. 9. Libythæidæ.
2. Satyridæ. 10. Nemeobiidæ.
3. Elymniidæ. 11. Eurygonidæ.
4. Morphidæ. 12. Erycinidæ.
5. Brassolidæ. 13. Lycænidæ.
6. Acræidæ. 14. Pieridæ.
7. Heliconidæ. 15. Papilionidæ.
8. Nymphalidæ. 16. Hesperidæ.

COLEOPTERA, OR BEETLES.

Fam. Fam.
1. Tiger-beetles. 4. Cetoniidæ Rose-chafers.
Cicindelidæ
2. Carabidæ Ground- 5. Buprestidæ Metallic Beetles.
beetles.
3. Lucanidæ Stag-beetles. 6. Long-horned
Longicornia Beetles.

The above families comprise the extensive series of ground beetles (Carabidæ)
containing about 9,000 species, and the Longicorns, which are nearly as numerous
and surpass them in variety of form and colour as well as in beauty. The Cetoniidæ
and Buprestidæ are among the largest and most brilliant of beetles; the Lucanidæ
are pre-eminent for remarkable form, and the Cicindelidæ for elegance; and all the
families are especial favourites with entomologists, so that the whole earth has
been ransacked to procure fresh species.

Results deduced from a study of these will, therefore, fairly represent the
phenomena of distribution of Coleoptera, and, as they are very varied in their
habits, perhaps of insects in general.

MOLLUSCA.

The Mollusca are usually divided into five classes as follows:—

I. Cephalopoda Cuttle-fish.
II. Gasteropoda Snails and aquatic Univalves.
III. Pteropoda Oceanic Snails.
IV. Brachiopoda Symmetrical Bivalves.
V. Conchifera Unsymmetrical Bivalves.

The Gasteropoda and Conchifera alone contain land and freshwater forms, and to
these we shall chiefly confine our illustrations of the geographical distribution of
the Mollusca. The classification followed is that of Dr. Pfeiffer for the Operculata
and Dr. Von Martens for the Helicidæ. The families chiefly referred to are:—

Class II.—GASTEROPODA.

Order 2.—Pulmonifera.

Fam.

1. Helicidæ.
2. Limacidæ.
3. Oncidiadæ.
In-operculata 4. Limnæidæ.
5. Auriculidæ.
6. Aciculidæ.
7. Diplommatinidæ.
8. Cyclostomidæ.
Operculata
9. Helicinidæ.

PART II.

ON THE DISTRIBUTION OF EXTINCT ANIMALS.

CHAPTER VI.

THE EXTINCT MAMMALIA OF THE OLD WORLD.

Although it may seem somewhat out of place to begin the systematic treatment of
our subject with extinct rather than with living animals, it is necessary to do so in
order that we may see the meaning and trace the causes of the existing distribution
of animal forms. It is true, that the animals found fossil in a country are very
generally allied to those which still inhabit it; but this is by no means universally
the case. If it were, the attempt to elucidate our subject by Palæontology would be
hopeless, since the past would show us the same puzzling diversities of faunas and
floras that now exist. We find however very numerous exceptions to this rule, and
it is these exceptions which tell us of the past migrations of whole groups of
animals. We are thus enabled to determine what portion of the existing races of
animals in a country are descendants of its ancient fauna, and which are
comparatively modern immigrants; and combining these movements of the forms
of life with known or probable changes in the distribution of land and sea, we shall
sometimes be able to trace approximately the long series of changes which have
resulted in the actual state of things. To gain this knowledge is our object in
studying the "Geographical Distribution of Animals," and our plan of study must
be determined, mainly, by the facilities it affords us for attaining this object. In
discussing the countless details of distribution we shall meet with in our survey of
the zoological regions, we shall often find it useful to refer to the evidence we
possess of the range of the group in question in past times; and when we attempt to
generalise the phenomena on a large scale, with the details fresh in our memory,
we shall find a reference to the extinct faunas of various epochs to be absolutely
necessary.

The degree of our knowledge of the Palæontology of various parts of the world is
so unequal, that it will not be advisable to treat the subject under each of our six
regions. Yet some subdivision must be made, and it seems best to consider
separately the extinct animals of the Old and of the New Worlds. Those of Europe
and Asia are intimately connected, and throw light on the past changes which have
led to the establishment of the three great continental Old World regions, with their
various subdivisions. The wonderful extinct fauna recently discovered in North
America, with what was previously known from South temperate America, not
only elucidates the past history of the whole continent, but also gives indications of
the mutual relations of the eastern and western hemispheres.

The materials to be dealt with are enormous; and it will be necessary to confine
ourselves to a general summary, with fuller details on those points which directly
bear upon our special subject. The objects of most interest to the pure zoologist
and to the geologist—those strange forms which are farthest removed from any
now living—are of least interest to us, since we aim at tracing the local origin or
birthplace of existing genera and families; and for this purpose animals whose
affinities with living forms are altogether doubtful, are of no value whatever.

The great mass of the vertebrate fossils of the tertiary period consist of mammalia,
and this is precisely the class which is of most value in the determination of
zoological regions. The animals of the secondary period, though of the highest
interest to the zoologist are of little importance to us; both because of their very
uncertain affinities for any existing groups, and also because we can form no
adequate notion of the distribution of land and sea in those remote epochs. Our
great object is to trace back, step by step, the varying distribution of the chief
forms of life; and to deduce, wherever possible, the physical changes which must
have accompanied or caused such changes. The natural division of our subject
therefore is into geological periods. We first go back to the Post-Pliocene period,
which includes that of the caves and gravels of Europe containing flint
implements, and extends back to the deposit of the glacial drift in the concluding
phase of the glacial epoch. Next we have the Pliocene period, divided into its later
portion (the Newer Pliocene) which includes the Glacial epoch of the northern
hemisphere; and its earlier portion (the Older Pliocene), represented by the red and
coralline crag of England, and deposits of similar age in the continent. During this
earlier epoch the climate was not very dissimilar from that which now prevails; but
we next get evidence of a still earlier period, the Miocene, when a warmer climate
prevailed in Europe, and the whole fauna and flora were very different. This is
perhaps the most interesting portion of the tertiary deposits, and furnishes us with
the most valuable materials for our present study. Further back still we have the
Eocene period, with apparently an almost tropical climate in Europe; and here we
find a clue to some of the most puzzling facts in the distribution of living animals.
Our knowledge of this epoch is however very imperfect; and we wait for
discoveries that will elucidate some of the mystery that still hangs over the origin
and migrations of many important families. Beyond this there is a great chasm in
the geological record as regards land animals; and we have to go so far back into
the past, that when we again meet with mammalia, birds, and land-reptiles, they
appear under such archaic forms that they cease to have any local or geographical
significance, and we can only refer them to wide-spread classes and orders. For the
purpose of elucidating geographical distribution, therefore, it is, in the present state
of our knowledge, unnecessary to go back beyond the tertiary period of geology.

The remains of Mammalia being so much more numerous and important than
those of other classes, we shall at first confine ourselves almost exclusively to
these. What is known of the birds, reptiles, and fishes of the tertiary epoch will be
best indicated by a brief connected sketch of their fossils in all parts of the globe,
which we shall give in a subsequent chapter.

Historic Period.—In tracing back the history of the organic world we find, even
within the limits of the historical period, that some animals have become extinct,
while the distribution of others has been materially changed. The Rytina of the
North Pacific, the dodo of Mauritius, and the great auk of the North Atlantic
coasts, have been exterminated almost in our own times. The kitchen-middens of
Denmark contain remains of the capercailzie, the Bos primigenius, and the beaver.
The first still abounds farther north, the second is extinct, and the third is becoming
so in Europe. The great Irish elk, a huge-antlered deer, probably existed almost
down to historic times.

Pleistocene or Post-Pliocene Period.—We first meet with proofs of important
changes in the character of the European fauna, in studying the remains found in
the caverns of England and France, which have recently been so well explored.
These cave-remains are probably all subsequent to the Glacial epoch, and they all
come within the period of man's occupation of the country. Yet we find clear
proofs of two distinct kinds of change in the forms of animal life. First we have a
change clearly traceable to a difference of climate. We find such arctic forms as the
rein-deer, the musk-sheep, the glutton, and the lemming, with the mammoth and
the woolly rhinoceros of the Siberian ice-cliffs, inhabiting this country and even
the south of France. This is held to be good proof that a sub-arctic climate
prevailed over all Central Europe; and this climate, together with the continental
condition of Britain, will sufficiently explain such a southward range of what are
now arctic forms.

But together with this change we have another that seems at first sight to be in an
exactly opposite direction. We meet with numerous animals which now only
inhabit Africa, or South Europe, or the warmer parts of Asia. Such are, large
felines—some closely related to the lion (Felis spelæa), others of altogether extinct
type (Machairodus) and forming the extreme development of the feline race;—
hyænas; horses of two or more species; and a hippopotamus. If we go a little
further back, to the remains furnished by the gravels and brick-earths, we still find
the same association of forms. The reindeer, the glutton, the musk-sheep, and the
woolly rhinoceros, are associated with several other species of rhinoceros and
elephant; with numerous civets, now abundant only in warm countries; and with

antelopes of several species. We also meet here with a great extension of range of
forms now limited to small areas. The Saiga antelope of Eastern Europe occurs in
France, where wild sheep and goats and the chamois were then found, together
with several species of deer, of bear, and of hyæna. A few extinct genera even
come down to this late period, such as the great sabre-toothed tiger, Machairodus;
Galeotherium, a form of Viverridæ; Palæospalax, allied to the mole; and
Trogontherium, a gigantic form of beaver,

We find then, that even at so early a stage of our inquiries we meet with a problem
in distribution by no means easy to solve. How are we to explain the banishment
from Europe in so short a space of time (geologically speaking) of so many forms
of life now characteristic of warmer countries, and this too during a period when
the climate of Central Europe was itself becoming warmer? Such a change must
almost certainly have been due to changes of physical geography, which we shall
be better able to understand when we have examined the preceding Pliocene
period. We may here notice, however, that so far as we yet know, this great recent
change in the character of the fauna is confined to the western part of the
Palæarctic region. In caves in the Altai Mountains examined by Prof. Brandt, a
great collection of fossil bones was discovered. These comprised the Siberian
rhinoceros and mammoth, and the cave hyæna; but all the others, more than thirty
distinct species, are now living in or near the same regions. We may perhaps
impute this difference to the fact that the migration of Southern types into this part
of Siberia was prevented by the great mountain and desert barrier of the Central
Asiatic plateau; whereas in Europe there was at this time a land connection with
Africa. Post-pliocene deposits and caverns in Algeria have yielded remains
resembling the more southern European types of the Post-pliocene period, but
without any admixture of Arctic forms; showing, as we might expect, that the
glacial cold did not extend so far south. We have here remains of Equus, Bos,
Antilope, Hippopotamus, Elephas, Rhinoceros, Ursus, Canis, and Hyæna, together
with Phacochœrus, an African type of swine which has not occurred in the
European deposits.

It is perhaps to the earlier portion of this period that the Merycotherium of the
Siberian drift belongs. This was an animal related to the living camel, thus
supporting the view that the Camelidæ are essentially denizens of the extra-
tropical zone.

Pliocene Period.

Primates.—We here first meet with evidence of the existence of monkeys in
Central Europe. Species of Macacus have left remains not only in the Newer
Pliocene of the Val d'Arno in Italy, but in beds of the same age at Grays in Essex;
while Semnopithecus and Cercopithecus, genera now confined to the Oriental and
Ethiopian regions respectively, have been found in the Pliocene deposits of the
South of France and Italy.

Carnivora.—Most of the genera which occurred in the Post-Pliocene are found
here also, and many of the same species. Few new forms appear, except
Hyænarctos, a large bear with characters approaching the hyænas, and Pristiphoca,
a new form of seal, both from the Older Pliocene of France; and Galecynus, a fox-
like animal intermediate between Canis and Viverra, from the Pliocene of
Œninghen in Switzerland.

Cetacea.—Species of Balæna, Physeter, and Delphinus occur in the Older
Pliocene of England and France, and with these the remains of many extinct forms,
Balænodon and Hoplocetus (Balænidæ); Belemnoziphius and Choneziphius
(Hyperoodontidæ), and Halitherium, an extinct form of the next order—Sirenia,
now confined to the tropics, although the recently extinct Rytina of the N. W.
Pacific shows that it is also adapted for temperate climates.

Ungulata.—The Pliocene deposits are not very rich in this order. The horses
(Equidæ) are represented by the genus Equus; and here we first meet with
Hipparion, in which small lateral toes appear. Both genera occur in British
deposits of this age. A more interesting fact for us is the occurrence of the genus
Tapirus in the Newer Pliocene of France and in the older beds of both France and
England, since this genus is now isolated in the remotest parts of the eastern and
western tropics. The genera Rhinoceros, Hippopotamus, and Sus, occur here as in
the preceding epoch.

We next come to the deer genus (Cervus), which appears to have been at its
maximum in this period, no less than eight species occurring in the Norwich Crag,
and Forest-beds. Among the Bovidæ, the antelopes, ox, and bison, are the only
forms represented here, as in the Post-Pliocene period. Passing on to the
Proboscidea, we find three species of elephants and two of Mastodon preserved in
European beds of this period, all distinct from those of Post-Pliocene times.

Rodentia.—In this order we find representatives of many living European forms;
as Cricetus (hamster), Arvicola (vole), Castor (beaver), Arctomys (marmot),

Hystrix (porcupine), Lepus (hare), and Lagomys (pika); and a few that are extinct,
the most important being Chalicomys, allied to the beaver; and Issiodromys, said to
come nearest to the remarkable Pedetes of South Africa, both found in the Pliocene
formations of France.

General Conclusions as to Pliocene and Post-Pliocene Faunas of Europe.—This
completes the series of fossil forms of the Pliocene deposits of Europe. They show
us that the presence of numerous large carnivora and ungulates (now almost
wholly tropical) in the Post-Pliocene period, was due to no exceptional or
temporary cause, but was the result of a natural succession from similar races
which had inhabited the same countries for long preceding ages. In order to
understand the vast periods of time covered by the Pliocene and Post-Pliocene
formations, the works of Sir Charles Lyell must be studied. We shall then come to
see, that the present condition of the fauna of Europe is wholly new and
exceptional. For a long succession of ages, various forms of monkeys, hyænas,
lions, horses, hipparions, tapirs, rhinoceroses, hippopotami, elephants, mastodons,
deer, and antelopes, together with almost all the forms now living, produced a rich
and varied fauna such as we now see only in the open country of tropical Africa.
During all this period we have no reason to believe that the climate or other
physical conditions of Europe were more favourable to the existence of these
animals than now. We must look upon them, therefore, as true indigenes of the
country, and their comparatively recent extinction or banishment as a remarkable
phenomenon for which there must have been some adequate cause. What this
cause was we can only conjecture; but it seems most probable that it was due to the
combined action of the Glacial period, and the subsidence of large areas of land
once connecting Europe with Africa. The existence, in the small island of Malta, of
no less than three extinct species of elephant (two of very small stature), of a
gigantic dormouse, an extinct hippopotamus, and other mammalia, together with
the occurrence of remains of hippopotamus in the caves of Gibraltar, indicate very
clearly that during the Pliocene epoch, and perhaps during a considerable part of
the Post-Pliocene, a connection existed between South Europe and North Africa in
at least these two localities. At the same time we have every reason to believe that
Britain was united to the Continent, what is now the German Ocean constituting a
great river-valley. During the height of the Glacial epoch, these large animals
would probably retire into this Mediterranean land and into North Africa, making
annual migrations northwards during the summer. But as the connecting land sank
and became narrower and narrower, the migrating herds would diminish, and at

last cease altogether; and when the glacial cold had passed away would be
altogether prevented from returning to their former haunts.

Miocene Period.

We now come to a period which was wonderfully rich in all forms of life, and of
which the geological record is exceptionally complete. Various lacustrine,
estuarine, and other deposits in Europe, North India, and North America, have
furnished such a vast number of remains of extinct mammalia, as to solve many
zoological problems, and to throw great light on the early distribution and centres
of dispersal of various groups of animals. In order to show the bearing of these
remains on our special subject, we will first give an account of the extinct fauna of
Greece, of the Upper Miocene period; since this, being nearest to Africa and Asia,
best exhibits the relations of the old European fauna to those countries. We shall
then pass to the Miocene fauna of France and Central Europe; and conclude with
the remarkable Siwalik and other Indian extinct faunas, which throw an additional
light on the early history of the animal life of the great old-world continents.

Extinct Animals of Greece.

These are from the Upper Miocene deposits at Pikermi, near Athens, and were
collected by M. Gaudry a few years ago. They comprise ten living and eighteen
extinct genera of mammalia, with a few birds and reptiles.

Primates.—These are represented by Mesopithecus, a genus believed to be
intermediate between the two Indian genera of monkeys, Semnopithecus and
Macacus.

Carnivora.—These were abundant. Of Felis there were four species, ranging from
the size of a cat to that of a jaguar, a large hyæna, and a large weasel (Mustela).
Besides these there were the huge Machairodus, larger than any existing lion or
tiger, and with enormously developed canine teeth; Hyænictis and Lycæna, extinct
forms of Hyænidæ; Thalassictis=Ictitherium, an extinct genus of Viverridæ but
with resemblances to the hyænas, represented by three species, some of which
were larger than any existing Viverridæ; Promephytis, an extinct form of
Mustelidæ, having resemblances to the European marten, to the otters, and to the
S. African Zorilla; and lastly, Simocyon, an extraordinary carnivore of the size of a

small panther, but having the canines of a cat, the molars of a dog, and the jaws
shaped like those of a bear.

Ungulata.—These are numerous and very interesting. The Equidæ are represented
by the three-toed Hipparion, which continued to exist till the Older Pliocene
period. There are three large species of Rhinoceros, as well as a species of the
extinct genus Leptodon of smaller size. Remains of a very large wild boar (Sus)
were found. Very interesting is the occurrence of a species of giraffe
(Camelopardalis) as tall as the African species but more slender; and also an
extinct genus Helladotherium, not quite so tall as the giraffe but much more
robust, and showing some approach to the Antilopidæ in its dentition. Antelopes
were abundant, ranging from the size of the gazelle to that of the largest living
species. Three or four seem referable to living genera, but the majority are of
extinct types, and are classed in the genera Palæotragus, Palæoryx, Tragocerus,
and Palæoreas; while Dremotherium is an ancient generalized form of Cervidæ or
deer.

Proboscidea.—These are represented by two species of Mastodon, and two of
Dinotherium, an extraordinary extinct form supposed to be, to some extent,
intermediate between the elephants and the aquatic manatees (Sirenia.)

Rodentia.—This order is represented by a species of Hystrix, larger than living
porcupines.

Edentata.—This order, now almost confined to South America, was represented in
the Miocene period by several European species. Ancylotherium and
Macrotherium, belonging to an extinct family but remotely allied to the African
ant-bear (Orycteropus), occur in Greece.

Birds.—Species of Phasianus and Gallus were found; the latter especially
interesting as being now confined to India.

Reptiles.—These are few and unimportant, consisting of a tortoise (Testudo) and a
large lizard allied to Varanus.

Summary of the Miocene Fauna of Greece.—Although we cannot consider that the
preceding enumeration gives us by any means a complete view of the actual

inhabitants of this part of Europe during the later portion of the Miocene period,
we yet obtain some important information. The resemblance that appeared in the
Pliocene fauna of Europe, to that of the open country of tropical Africa, is now still
more remarkable. We not only find great felines, surpassing in size and destructive
power the lions and leopards of Africa, with hyænas of a size and in a variety not
to be equalled now, but also huge rhinoceroses and elephants, two forms of
giraffes, and a host of antelopes, which, from the sample here obtained, were
probably quite as numerous and varied as they now are in Africa. Joined with this
abundance of antelopes we have the absence of deer, which probably indicates that
the country was open and somewhat of a desert character, since there were deer in
other parts of Europe at this epoch. The occurrence of but a single species of
monkey is also favourable to this view, since a well-wooded country would most
likely have supplied many forms of these animals.

Miocene Fauna of Central and Western Europe.

We have now to consider the Miocene fauna of Europe generally, of which we
have very full information from numerous deposits of this age in France,
Switzerland, Italy, Germany, and Hungary.

Primates.—Three distinct forms of monkeys have been found in Europe—in the
South of France, in Switzerland, and Wurtemberg; one was very like Colobus or
Semnopithecus; the others—Pliopithecus and Dryopithecus—were of higher type,
and belonged to the anthropomorphous apes, being nearest to the genus Hylobates
or gibbons. Both have occurred in the South of France. The Dryopithecus was a
very large animal (equal to the gorilla), and M. Lartet considers that in the
character of its dentition it approached nearer to man than any of the existing
anthropoid apes.

Insectivora.—These small animals are represented by numerous remains
belonging to four families and a dozen genera. Of Erinaceus (hedgehog) several
species are found in the Upper Miocene; and in the Lower Miocene of Auvergne
two extinct genera of the same family—Amphechinus and Tetracus—have been
discovered. Several species of Talpa (mole) occur in the Upper Miocene of France,
while the extinct Dinylus is from Germany, and Palæospalax from the Lower
Miocene of the Isle of Wight. The Malayan family Tupaiidæ or squirrel-shrews, is
believed to be represented by Oxygomphus, a fossil discovered in South Germany
(Wiesenau) by H. von Meyer. The Soricidæ or shrews, are represented by several
extinct genera—Plesiosorex, Mysarachne and Galeospalax; as well as by

Amphisorex and Myogale still living. Echinogale, a genus of Centetidæ now
confined to Madagascar, is said to occur in the Lower Miocene of Auvergne, a
most interesting determination, if correct, as it would form a transition to the
Solenodon of the Antilles belonging to the same family; but I am informed by Prof.
Flower that the affinities of the animals described under this name are very
doubtful.

Carnivora.—Besides Felis and Machairodus, which extend back to the Upper
Miocene, there are two other genera of Felidæ, Pseudælurus in the Upper Miocene
of France, and Hyænodon, which occurs in the Upper and Lower Miocene of
France, named from some resemblance in its teeth to the hyænas, and considered
by some Palæontologists to form a distinct family, Hyænodontidæ. The Viverridæ,
or civets, were very numerous, consisting of the living genus Viverra, and three
extinct forms—Thalassictis=Ictitherium, as large as a panther, and Soricictis, a
smaller form, occurring both in France and Hungary. Of Hyænidæ, there was the
living genus Hyæna, and the extinct Hyænictis, which has occurred in Hungary as
well as in Greece. The Canidæ, or wolf and fox family, were represented by
Pseudocyon, near to Canis; Hemicyon, intermediate between dogs and gluttons;
and Amphicyon, of which several species occur in the Upper and Lower Miocene
of France, some of them larger than a tiger. The Mustelidæ, or weasels, were
represented by five genera, the existing genera Lutra (otter) and Mustela (weasel);
Potamotherium, an extinct form of otter; Taxodon, allied to the badger and otter;
Palæomephitis in Germany, and the Promephytis (already noticed) in Greece. The
bears were represented only by Hyænarctos, which has been noticed as occurring
in the Pliocene, and first appears in the Upper Miocene of France. Seals are
represented by a form resembling the Antarctic Otaria, remains of which occur in
the Upper Miocene of France.

Cetacea (whales).—These occur frequently in the Miocene deposits, four living,
and five extinct genera having been described; but these marine forms are not of
much importance for our purpose.

Sirenia (sea-cows).—These are represented by two extinct genera, Halitherium
and Trachytherium. Several species of the former have been discovered, but the
latter has occurred in France only, and its affinities are doubtful.

Ungulata.—Horses are represented by Hipparion and Anchitherium, the latter
occurring in both Upper and Lower Miocene and Eocene; while Hipparion, which
is more nearly allied to living horses, first appears in the Upper Miocene and
continues in the Pliocene.

Hippotherium, in the Upper Miocene of the Vienna basin, forms a transition to
Paloplotherium, an Eocene genus of Tapiridæ or Palæotheridæ. Tapirs, allied to
living forms, occur in both Upper and Lower Miocene. Rhinoceroses are still
found in the Upper Miocene, and here first appear the four-toed hornless
rhinoceros, Acerotherium. The Suidæ (swine) are rather numerous. Sus (wild boar)
continued as far back as the Upper Miocene; but now there first appear a number
of extinct forms which have been named Hyotherium, Palæochœrus, Chœromorus,
all of a small or moderate size; Hyopotamus, nearly as large as a tapir; and
Anthracotherium, nearly the size of a hippopotamus and, according to Dr. Leidy,
the type of a distinct family. Listriodon, from the Upper Miocene of the Vienna
basin, is sometimes classed with the tapirs.

We now come to a well-marked new family of Artiodactyle or even-toed Ungulata,
the Anoplotheriidæ, which consisted of more slender long-tailed animals, allied to
the swine but with indications of a transition towards the camels. The only genera
that appear in the Miocene formation are, Chalicotherium, nearly as large as a
rhinoceros, of which three species have been found in Germany and France; and
Synaphodus, known only from its teeth, which differ somewhat from those of the
Anoplotherium which appears earlier in the Eocene formation. Another extinct
family, Amphimericidæ or Xiphodontidæ, is represented by two genera,
Cainotherium and Microtherium, in the Miocene of France. They were of very
small size, and are supposed to be intermediate between the Suidæ and Tragulidæ.

The Camelopardalidæ, or giraffes, were represented in Europe in Miocene times
by the gigantic Helladotherium, which has been found in the south of France, and
in Hungary, as well as in Greece. The chevrotains (Tragulidæ) are represented by
the extinct genus Hyomoschus.

The Cervidæ do not seem to have appeared in Europe before the Upper Miocene
epoch, when they were represented by Dorcatherium and Amphimoschus, allied to
Moschus, and also by true Cervus, as well as by small allied forms, Dremotherium,
Amphitragalus (in the Lower Miocene), Micromeryx, Palæomeryx, and
Dicrocerus.

The Bovidæ, or hollow-horned ruminants, were not well represented in Central
Europe in Miocene times. There were no sheep, goats, or oxen, and only a few
antelopes of the genus Tragocerus, and one allied to Hippotragus; and these all
lived in the Upper Miocene period, as did the more numerous forms of Greece.

Proboscidea.—The true elephants do not extend back to the Miocene period, but
they are represented by the Mastodons, which had less complex teeth. These first
appear in the Upper Miocene of Europe, five species being known from France,
Germany, Switzerland, and Greece. Dinotherium, already noticed as occurring in
Greece, extended also to Germany and France, where remains of three species
have been found.

Rodentia.—A considerable number of generic forms of this order have been
obtained from the Miocene strata. The principal genera are Cricetodon, allied to
the hamsters, numerous in both the Upper and Lower Miocene period of France;
Myoxus (the dormice) in France, and an allied genus, Brachymys, in Germany. The
beavers were represented by the still living genus Castor, and the extinct
Steneofiber in France. The squirrels by the existing Scuirus and Spermophilus; and
by extinct forms, Lithomys and Aulacodon, in Germany, the latter resembling the
African genus Aulacodes. The hares, by Lagomys and an extinct form Titanomys.
Besides these, remains referred to the South American genera, Cavia (cavy) and
Dasyprocta (agouti), have been found, the former in the Upper Miocene of
Switzerland, the latter in the Lower Miocene of Auvergne. Palæomys, allied to the
West Indian Capromys, has been found in the same deposits; as well as
Theridomys, said by Gervais to be allied to Anomalurus and Echimys, the former
now living in W. Africa, the latter in S. America.

Edentata.—These are only represented by the Macrotherium and Ancylotherium of
the Grecian deposits, the former occurring also in France and Germany in Upper
Miocene strata.

Marsupials.—These consist of numerous species related to the opossums
(Didelphys), but separated by Gervais under the name Peratherium. They occur in
both Upper and Lower Miocene beds.

Upper Miocene Deposits of the Siwalik Hills and other Localities in N. W. India.

These remarkable fresh-water deposits form a range of hills at the foot of the
Himalayas, a little south of Simla. They were investigated for many years by Sir P.
Cautley and Dr. Falconer, and add greatly to our knowledge of the early fauna of
the Old World continent.

Primates.—Remains of the genera Semnopithecus and Macacus were found, with
other forms of intermediate character; and some teeth indicated animals allied to

the orang-utan of Borneo, and of similar size.

Carnivora.—These consisted of species of Felis and Machairodus of large size;
Hyæna, Canis, Mellivora, and an allied genus Ursitaxus; Ursus, in the deposits of
the Nerbudda valley (of Pliocene age); Hyænarctos as large as the cave bear;
Amphicyon of the size of a polar bear (in the deposits of the Indus valley, west of
Cashmere); Lutra, and an extinct allied genus Enhydrion.

Ungulata.—These are very numerous, and constitute the most important feature of
this ancient fauna. Horses are represented by a species of Equus from the Siwalik
Hills and the Irawaddy deposits in Burmah, and by two others from the Pliocene of
the Nerbudda Valley; while Hippotherium—a slender, antelope-like animal, found
in the Siwalik Hills and in Europe—is supposed to form a transition from the
Equidæ to the Tapiridæ. These latter are found in the Upper Indus deposits, where
there is a species of Tapirus, and one of an extinct genus Antelotherium. Of
Rhinoceros, five extinct species have been found—in the Siwalik Hills, in Perim
Island, and one at an elevation of 16,000 feet in the deserts of Thibet.
Hippopotamus occurs in the Pliocene of the Nerbudda, and is represented in the
older Miocene deposits by Hexaprotodon, of which three species have been found
in various parts of India. Another remarkable genus, Merycopotamus, connects
Hippopotamus with Anthracotherium, one of the extinct European forms allied to
the swine. These last are represented by several large species of Sus, and by the
extinct European genus Chœrotherium.

The extinct Anoplotheridæ are represented by a species of the European genus
Chalicotherium, larger than a horse.

An extinct camel, larger than the living species, was found in the Siwalik Hills.

Three species of deer (Cervus) have been found in the Siwaliks, and one in the
Nerbudda deposits.

A large and a small species of giraffe (Camelopardalis) were found in the Siwalik
Hills and at Perim Island.

The Bovidæ are represented by numerous species of Bos, and by the extinct genera
Hemibos and Amphibos. There are also three species of antelopes, one of which is
allied to the African Alcephalus.

We now come to an extraordinary group of extinct animals, probably forming a
new family intermediate between the antelope and the giraffe. The Sivatherium
was an enormous four-horned ruminant, larger than a rhinoceros. It had a short
trunk like a tapir, the lower horns on the forehead were simple, the upper pair
palmated. The Bramatherium, an allied form from Perim Island, showed somewhat
more affinity for the giraffe.

Proboscidea.—No less than seven species of elephants and four of mastodons
ranged over India, their remains being found in all the deposits from the Siwalik
Hills to Burmah. A large Dinotherium has also been found at Perim Island.

Reptiles.—Many remains of birds were found, but these have not been determined.
Reptiles were numerous and interesting, the most remarkable being the huge
tortoise, Colossochelys, whose shell was twelve feet long and head and neck eight
feet more. Other small tortoises of the genera Testudo, Emys, Trionyx and Emydida
were found, the Emys being a living species. There were three extinct and one
living species of crocodile, and one of them was larger than any now living. The
only other reptile of importance was a large lizard of the genus Varanus.

General Observations on the Miocene faunas of Europe and Asia.—Comparing
the three faunas of approximately the same period, and allowing for the necessarily
imperfect record of each, we find a wonderful similarity of general type over the
enormous area between France on the west and the Irawaddy river in Burmah on
the east. We may even extend our comparison to Northern China, where remains of
Hyæna, Tapir, Rhinoceros, Chalicotherium, and Elephas, have been recently
found, closely resembling those from the Miocene or Pliocene deposits of Europe
or India, and showing that the Palæarctic region had then the same great extent
from west to east that it has now. Of about forty genera comprised in the Indian
Miocene fauna, no less than twenty-seven inhabited Central and Western Europe
during the same epoch. The Indian Miocene fossils are much what we should
expect as the forerunners of the existing fauna, the giraffes and hippopotami being
the only additions from the present Ethiopian fauna. The numerous forms of the
restricted bovine type, show that these probably originated in India; while the
monkeys appear to be altogether of Oriental types.

In Europe, however, we meet with a totally different assemblage of animals from
those that form the existing fauna. We find apes and monkeys, many large Felidæ,

numerous civets and hyænas, tapirs, rhinoceros, hippopotamus, elephants, giraffes,
and antelopes, such as now characterise the tropics of Africa and Asia. Along with
these we meet with less familiar types, showing relations with the Centetidæ of
Madagascar, the Tupaiidæ of the Malay Islands, the Capromys, of the West Indies,
and the Echimys of South America. And besides all these living types we have a
host of extinct forms,—ten or twelve genera allied to swine; nine genera of tapir-
like animals; four of horses; nine of wolves; with many distinct forms of the long-
extinct families of Anoplotheridæ, Xiphodontidæ, and the edentate Macrotheridæ.
It is almost certain that during the Miocene period Europe was not only far richer
than it is now in the higher forms of life, but not improbably richer than any part of
the globe now is, not excepting tropical Africa and tropical Asia.

Eocene Period.

The deposits of Eocene age are less numerous, and spread over a far more limited
area, than those of the Miocene period, and only restricted portions of them furnish
any remains of land animals. Our knowledge of the Eocene mammalian fauna is
therefore very imperfect and will not occupy us long, as most of the new types it
furnishes are of more interest to the zoologist than to the student of distribution.
Some of the Eocene mammalia of Europe are, however, of interest in comparison
with those of North America of the same age; while others show that ancestral
types of groups now confined to Australia or to South America, then inhabited
Europe.

Primates.—The only undoubted Eocene examples of this order, are the
Cænopithecus lemuroides from the Jura, which has points of resemblance to the
South American marmosets and howlers, and also to the Lemuridæ; and a cranium
recently discovered in the Department of Lot (S.W. France), undoubtedly
belonging to the Lemuridæ, and which most resembles that of the West African
"Potto" (Perodicticus). This discovery has led to another, for it is now believed that
remains formerly referred to the Anoplotheridæ (Adapis and Aphelotherium from
the Upper Eocene of Paris) were also Lemurs. Some remains from the Lower
Eocene of Suffolk were at first supposed to be allied to Macacus, but were
subsequently referred to the Ungulate, Hyracotherium. There is still, however,
some doubt as to its true affinities.

Chiroptera.—In the Upper Eocene of Paris remains of bats have been found, so
closely resembling living forms as to be referred to the genus Vespertilio.

Carnivora.—The only feline remains, are those of Hyænodon in the Upper Eocene
of Hampshire, and Pterodon, an allied form from beds of the same age in France;
with Ælurogale, found in the South of France in deposits of phosphate of lime of
uncertain age, but probably belonging to this period. Viverridæ (civets) are
represented by two genera, Tylodon, the size of a glutton from the Upper Eocene,
and Palæonyctis, allied to Viverra, from the Middle Eocene of France. The Canidæ
(wolves and foxes) appear to have been the most ancient of the existing types of
Carnivora, five genera being represented by Eocene remains. Of these, Galethylax
and Cyotherium were small, and with the existing genus Canis are found in the
Upper Eocene of France. Arctocyon, about the size of a wolf, is a very ancient and
generalised form of carnivore which can not be placed in any existing family. It is
found in the Lower Eocene of France, and is thus the oldest known member of the
Carnivora.

Ungulata.—These are more numerous. Equidæ (horses) are represented by the
Miocene Anchitherium in the Lower, and by a more ancient form, Anchilophus, in
the Middle Eocene of France. Tapiridæ and Palæotheridæ were very numerous.
Palæotherium and the allied genus Paloplotherium, were abundant in France and
England in Upper Eocene times. They somewhat resembled the tapir, with
affinities for the horse and rhinoceros. A new genus, Cadurcotherium, allied to the
rhinoceros and equally large, has been found in the same deposits of phosphate of
lime as the lemur and Ælurogale. In the Middle Eocene of both England and
France are found Lophiodon allied to the tapir, but in some of the species reaching
a larger size; Propalæotherium and Pachynolophus of smaller size and having
affinities for the other genera named; and Plagiolophus, a small, slender animal
which Professor Huxley thinks may have been a direct ancestor of the horse. In the
Lower Eocene we meet with Coryphodon, much larger than the tapir, and armed
with large canine teeth; Pliolophus, a generalised type, allied to the tapir and horse;
and Hyracotherium, a small animal from the Lower Eocene of England, remotely
allied to the tapir.

Among the Artiodactyla, or even-toed ungulates, the swine are represented by
several extinct genera, of moderate or small size—Acotherium, Chœropotamus,
Cebochœrus and Dichobune, all from the Upper and the last also from the Middle
Eocene of France; but Eutelodon, from the phosphate of lime deposits is large. The
Dichobune was the most generalised type, presenting the characters of many of the
other genera combined, and was believed by Dr. Falconer to approach the musk-
deer. The Cainotherium of the Miocene also occurs here, and an allied genus
Plesiomeryx from the same deposits as Euteledon.

The Eocene Anoplotheridæ were numerous. The Anoplotherium was a two-toed,
long-tailed Pachyderm, ranging from the size of a hog to that of an ass; the allied
Eurytherium was four-toed; and there are one or two others of doubtful affinity. All
are from the Upper Eocene of France and England.

Rodentia.—Remains referred to the genera Myoxus (dormouse) and Sciurus
(squirrel) have been found in the Upper Eocene of France; as well as
Plesiarctomys, an extinct genus between the marmots and squirrels. The Miocene
Theridomys is also found here.

Marsupials.—The Didelphys (opossum) of Cuvier, now referred to an extinct
genus Peratherium, is found in the Upper Eocene of France and England.

General Considerations on the Extinct Mammalian Fauna of Europe.—It is a
curious fact that no family, and hardly a genus, of European mammalia occurs in
the Pliocene deposits, without extending back also into those of Miocene age.
There are, however, a few groups which, seem to be late developments or recent
importations into the Palæarctic region, as they occur only in Post-Pliocene
deposits. The most important of these are the badger, glutton, elk, reindeer,
chamois, goat, and sheep, which only occur in caves and other deposits of Post-
Pliocene age. Camels only occur in the Post-Pliocene of Siberia (Merycotherium),
although a true Camelus of large size appears to have inhabited some part of
Central Asia in the Upper Miocene period, being found in the Siwalik beds. The
only exclusively Pliocene genera in Europe are Ursus, Equus, Hippopotamus, Bos,
Elephas, Arvicola, Trogontherium, Arctomys, Hystrix and Lepus; but of these
Equus, Hippopotamus, Bos, and Elephas are found in the Miocene deposits of
India. Owing, no doubt, in part to the superior productiveness of the various
Miocene beds, large numbers of groups appear to have their origin or earliest
appearance here. Such are Insectivora, Felidæ, Hyænidæ, Mustelidæ, Ursus,
Equidæ, Tapirus, Rhinocerotidæ, Hippopotamidæ, Anthracotheridæ (extinct), Sus,
Camelopardidæ, Tragulidæ, Cervidæ, Bovidæ, Elephantidæ, and Edentata.

Groups which go back to the Eocene period, are, Primates allied to South
American monkeys, as well as some of the Lemuridæ; bats of the living genus
Vespertilio; Hyænodontidæ, an ancestral form of Carnivore; Viverridæ; Canidæ (to
the Upper Eocene), and the ancestral Arctocyonidæ to the Lower Eocene;
Hyænarctos, an ancestral type of bears and hyænas; Anchitheridæ, ancestral

horses, to the Middle Eocene; Palæotheridæ, comprising numerous generalised
forms, ancestors of the rhinoceros, horse, and tapir; Suidæ, with numerous
generalised forms, to the Middle Eocene; Anoplotheridæ and Xiphodontidæ,
ancestral families of even-toed Ungulates, connecting the ruminants with the
swine; and lastly, several groups of Rodents, and a Marsupial, in the Upper
Eocene. We thus find all the great types of Mammalia well developed in the
earliest portion of the tertiary period; and the occurrence of Quadrumana, of the
highly specialized bats (Vespertilio), of various forms of Carnivora, and of
Ungulates, clearly differentiated into the odd and even-toed series, associated with
such lower forms as Lemurs and Marsupials—proves, that we have here hardly
made an approach towards the epoch when the mammalian type itself began to
diverge into its various modifications. Some of the Carnivora and Ungulates do,
indeed, exhibit a less specialised structure than later forms; yet so far back as the
Upper Miocene the most specialised of all carnivora, the great sabre-toothed
Machairodus, makes its appearance.

The Miocene is, for our special study, the most valuable and instructive of the
Tertiary periods, both on account of its superior richness, and because we here
meet with many types now confined to separate regions. Such facts as the
occurrence in Europe during this period of hippopotami, tapirs, giraffes,
Tragulidæ, Edentata, and Marsupials—will assist us in solving many of the
problems we shall meet with in reviewing the actual distribution of living forms of
those groups. Still more light will, however, be thrown on the subject by the fossil
forms of the American continent, which we will now proceed to examine.

CHAPTER VII.

EXTINCT MAMMALIA OF THE NEW WORLD.

The discoveries of very rich deposits of mammalian remains in various parts of the
United States have thrown great light on the relations of the faunas of very distant
regions. North America now makes a near approach to Europe in the number and
variety of its extinct mammalia, and in no part of the world have such perfect
specimens been discovered. In what are called the "Mauvaises terres" of Nebraska
(the dried-up mud of an ancient lake), thousands of entire crania and some almost
entire skeletons of ancient animals have been found, their teeth absolutely perfect,
and altogether more resembling the preparations of the anatomist, than time-worn
fossils such as we are accustomed to see in the museums of Europe. Other deposits
have been discovered in Oregon, California, Virginia, South Carolina, Texas, and
Utah, ranging over all the Tertiary epochs, from Post-Pliocene to Eocene, and
furnishing a remarkable picture of the numerous strange mammalia which
inhabited the ancient North American continent.

North America—Post-Pliocene Period.

Insectivora.—The only indications of this order yet discovered, consists of a single
tooth of some insectivorous animal found in Illinois, but which cannot be referred
to any known group.

Carnivora.—These are fairly represented. Two species of Felis as large as a lion;
the equally large extinct Trucifelis, found only in Texas; four species of Canis,
some of them larger than wolves; two species of Galera, a genus now confined to
the Neotropical region; two bears, and an extinct genus, Arctodus; an extinct
species of racoon (Procyon), and an allied extinct genus, Myxophagus—show, that
at a very recent period North America was better supplied with Carnivora than it is
now. Remains of the walrus (Trichechus) have also been found as far south as
Virginia.

Cetacea.—Three species of dolphins belonging to existing genera, have been
found in the Eastern States; and two species of Manatus, or sea-cow, in Florida and
South Carolina.

Ungulata.—Six extinct horses (Equus), and one Hipparion; the living South
American tapir, and a larger extinct species; a Dicotyles, or peccary, and an allied

genus, Platygonus; a species of the South American llamas (Auchenia), and one of
a kind of camel, Procamelus; two extinct bisons; a sheep, and two musk-sheep
(Ovibos); with three living and one extinct deer (Cervus), show an important
increase in its Herbivora.

Proboscidea.—Two elephants and two mastodons, added to this remarkable
assemblage of large vegetable-feeding quadrupeds.

Rodentia.—These consist mainly of genera and species still living in North
America; the only important exceptions being a species of the South American
capybara (Hydrochœrus) in South Carolina; and Praotherium, an extinct form of
hare, found in a bone cave in Pennsylvania.

Edentata.—Here we meet with a wonderful assemblage, of six species belonging
to four extinct genera, mostly of gigantic size. A species of Megatherium, three of
Megalonyx, and one of Mylodon—huge terrestrial sloths as large as the rhinoceros
or even as the largest elephants—ranged over the Southern States to Pennsylvania,
the latter (Mylodon) going as far as the great lakes and Oregon. Another form,
Ereptodon, has been found in the Mississippi Valley.

Marsupialia.—The living American genus of opossums, Didelphys, has been
found in deposits of this age in South Carolina.

Remarks on the Post-Pliocene fauna of North America.—The assemblage of
animals proved, by these remains, to have inhabited North America at a
comparatively recent epoch, is most remarkable. In Europe, we found a striking
change in the fauna at the same period; but that consisted almost wholly in the
presence of animals now inhabiting countries immediately to the north or south.
Here we have the appearance of two new assemblages of animals, the one now
confined to the Old World—horses, camels, and elephants; the other exclusively of
South American type—llamas, tapirs, capybaras, Galera, and gigantic Edentata.
The age of the various deposits in which these remains are found is somewhat
uncertain, and probably extends over a considerable period of time, inclusive of
the Glacial epoch, and perhaps both anterior and subsequent to it. We have here, as
in Europe, the presence and apparent co-existence in the same area, of Arctic and
Southern forms—the walrus and the manatee—the musk-sheep and the gigantic
sloths. Unfortunately, as we shall see, the immediately preceding Pliocene deposits

of North America are rather poor in organic remains; yet it can hardly be owing to
the imperfection of the record of this period, that not one of the South American
types above numerated occurs there, while a considerable number of Old World
forms are represented. Neither in the preceding wonderfully rich Miocene or
Eocene periods, does any one of these forms occur; or, with the exception of
Morotherium, from Pliocene deposits west of the Rocky Mountains, any apparent
ancestor of them! We have here unmistakable evidence of an extensive
immigration from South into North America, not very long before the beginning of
the Glacial epoch. It was an immigration of types altogether new to the country,
which spread over all the southern and central portions of it, and established
themselves sufficiently to leave abundance of remains in the few detached
localities where they have been discovered. How such large yet defenceless
animals as tapirs and great terrestrial sloths, could have made their way into a
country abounding in large felines equal in size and destructiveness to the lion and
the tiger, with numerous wolves and bears of the largest size, is a great mystery.
But it is nevertheless certain that they did so; and the fact that no such migration
had occurred for countless preceding ages, proves that some great barrier to the
entrance of terrestrial mammalia which had previously existed, must for a time
have been removed. We must defer further discussion of this subject till we have
examined the relations of the existing faunas of North and South America.

Tertiary Period.

When we get to remains of the Tertiary age, especially those of the Miocene and
Eocene epochs, we meet with so many interesting and connected types, and such
curious relations with living forms in Europe, that it will be clearer to trace the
history of each order and family throughout the Tertiary period, instead of
considering each of the subdivisions of that period separately.

It will be well however first to note the few American Post-Pliocene or living
genera that are found in the Pliocene beds. These consist of several species of
Canis, from the size of a fox to that of a large wolf; a Felis as large as a tiger; an
Otter (Lutra); several species of Hipparion; a peccary (Dicotyles); a deer (Cervus);
several species of Procamelus; a mastodon; an elephant; and a beaver (Castor). It
thus appears that out of nearly forty genera found in the Post-Pliocene deposits,
only ten are found in the preceding Pliocene period. About twelve additional
genera, however, appear there, as we shall see in going over the various orders.

Primates.—Among the vast number of extinct mammalia discovered in the
Tertiary deposits of North America, no example of this order had been recognized
up to 1872, when the discovery of more perfect remains showed, that a number of
small animals of obscure affinities from the Lower Eocene of Wyoming, were
really allied to the lemurs and perhaps also to the marmosets, the lowest form of
American monkeys, but having a larger number of teeth than either. A number of
other remains of small animals from the same formation, previously supposed to
be allied to the Ungulata, are now shown to belong to the Primates; so that no less
than twelve genera of these animals are recognized by Mr. Marsh, who classes
them in two families—Limnotheridæ, comprising the genera Limnotherium,
(which had larger canine teeth), Thinolestes, Telmatolestes, Mesacodon,
Bathrodon, and Antiacodon of Marsh, with Notharctos, Hipposyus, Microsyops,
and Palæacodon previously described by Leidy;—and Lemuravidæ, consisting of
the genera Lemuravus (Marsh) and Hyopsodus (Leidy). The animals of the latter
family were most allied to existing lemurs, but were a more generalized form,
Lemuravus having forty-four teeth, the greatest number known in the order. These
numerous forms ranged from the size of a small squirrel to that of a racoon. It is
especially interesting to find these peculiar lemuroid forms in America, just when a
lemur has been discovered of about the same age in Europe; and as the American
forms are said to show an affinity with the South American marmosets, while the
European animal is most allied to a West African group, we have evidently not yet
got back far enough to find the primeval or ancestral type from which all the
Primates sprang.

About the same time, in the succeeding Miocene formation, true monkeys were
discovered. Mr. Marsh describes Laopithecus as an animal nearly the size of the
largest South American monkeys, and allied both to the Cebidæ and the Eocene
Limnotheridæ. Mr. Cope has described Menotherium from the Miocene of
Colorado, as a lemuroid animal, the size of a cat, and perhaps allied to
Limnotherium. More Miocene remains will, no doubt, be discovered, by which we
shall be enabled to trace the origin of some of the existing forms of South
American monkeys; and perhaps help to decide the question (now in dispute
among anatomists) whether the lemurs are really Primates, or form an altogether
distinct and isolated order of mammalia.

Insectivora.—This order is represented by comparatively few forms in the tertiary
beds, and these are all very different from existing types. In the Upper Miocene of
Dakota are found remains indicating two extinct genera, Lepictis and Ictops. In the
Miocene of Colorado, Professor Cope has recently discovered four new genera,
Isacis; allied to the preceding, but as large as a Mephitis or skunk; Herpetotherium,

near the moles; Embasis, more allied to the shrews; and Dommina, of uncertain
affinities. Two others have been found in the Eocene of Wyoming; Amomys,
having some resemblance to hedgehogs and to the Eastern Tupaia; and Washakius,
of doubtful affinities.

Far back in the Triassic coal of North Carolina has been found the jaw of a small
mammal (Dromotherium), the teeth of which somewhat resemble those of the
Australian Myrmecobius, and may belong either to the Insectivora or Marsupials;
if indeed, at that early period these orders were differentiated.

Carnivora.—The most ancient forms of this order are some remains found in the
Middle Eocene of Wyoming, and others recently described by Professor Cope
(1875) from the Eocene of New Mexico, of perhaps earlier date. The former
consist of three genera, Patriofelis, Uintacyon, and Sinopa,—animals of large size
but which cannot be classed in any existing family; and two others, Mesonyx and
Synoplotherium, believed by Mr. Cope to be allied to Hyænodon. The latter consist
of four genera,— Oxyæna, consisting of several species, some as large as a jaguar,
was allied to Hyænodon and Pterodon; Pachyæna, allied to the last; Prototomus,
allied to Amphicyon and the Viverridæ; and Limnocyon, a civet-like carnivore with
resemblances to the Canidæ.

In the Miocene formations we find the Feline type well developed. The wonderful
Machairodus, which in Europe lived down to Post-Pliocene times, is found in the
Upper Miocene of Dakota; and perfect crania have been discovered, showing that
the chin was lengthened downwards to receive and protect the enormous canines.
Dinyctis was allied both to Machairodus and to the weasels. Three new genera
have been lately described by Professor Cope from the Miocene of Colorado,—
Bunælurus, with characters of both cats and weasels; Daptophilus, allied to
Dinyctis; and Hoplophoneus, more allied to Machairodus. The Canidæ are
represented by Amphicyon, which occurs in deposits of the same age in Europe;
and by Canis, four species of which genus are recorded by Professor Cope from
the Miocene of Colorado, and it also occurs in the Pliocene. The Hyænodon is
represented by three species in the Miocene of Dakota and Colorado. It occurs also
in the European Miocene and Upper Eocene formations, and constitutes a distinct
family Hyænodontidæ, allied, according to Dr. Leidy, to wolves, cats, hyænas and
weasels. The Ursidæ are represented by only one species of an extinct genus,
Leptarchus, from the Pliocene of Nebraska. From the Pliocene of Colorado, Prof.
Cope has recently described Tomarctos, as a "short-faced type of dog;" well as
species of Canis and Martes.

Ungulata.—The animals belonging to this order being usually of large size and
accustomed to feed and travel in herds, are liable to wholesale destruction by
floods, bogs, precipices, drought or hunger. It is for these reasons, probably, that
their remains are almost always more numerous than those of other orders of
mammalia. In America they are especially abundant; and the number of new and
intermediate types about whose position there is much difference of opinion
among Palæontologists, renders it very difficult to give a connected summary of
them with any approach to systematic accuracy.

Beginning with the Perissodactyla, or odd-toed ungulates, we find the Equine
animals remarkably numerous and interesting. The true horses of the genus Equus,
so abundant in the Post-Pliocene formations, are represented in the Pliocene by
several ancestral forms. The most nearly allied to Equus is Pliohippus, consisting
of animals about the size of an ass, with the lateral toes not externally developed,
but with some differences of dentition. Next come Protohippus and Hipparion, in
which the lateral toes are developed but are small and functionless. Then we have
the allied genera, Anchippus, Merychippus, and Hyohippus, related to the
European Hippotherium, which were all still smaller animals, Protohippus being
only 2½ feet high. In the older deposits we come to a series of forms, still
unmistakably equine, but with three or more toes used for locomotion and with
numerous differentiations in form, proportions, and dentition. These constitute the
family Anchitheridæ. In the Miocene we have the genera Anchitherium (found also
in the European Miocene), Miohippus and Mesohippus, all with three toes on each
foot, and about the size of a sheep or large goat. In the Eocene of Utah and
Wyoming, we get a step further back, several species having been discovered
about the size of a fox with four toes in front and three behind. These form the
genus Orohippus, and are the oldest ancestral horse known. Prof. Marsh points out
the remarkably perfect series of forms in America, which, beginning with this
minute ancient type, is gradually modified by gaining increased size, increased
speed by concentration of the limb-bones, elongation of the head and neck, the
canine teeth decreased in size, the molars becoming longer and being coated with
cement—till we at last come to animals hardly distinguishable, specifically, from
the living horse.

Allied to these, are a series of forms showing a transition to the tapirs, and to the
Palæotherium of the European Eocene. In the Pliocene we have Parahippus; in the
Miocene Lophiodon, found in the same formation and in the Eocene of Europe,
and allied to the tapir; and in the Eocene, Palæosyops, as large as a rhinoceros,
which had large canines and was allied to the tapir and Palæotherium; Limnohyus,
forming the type of a family Limnohyidæ, which included the last genus and some

others mentioned further on; and Hyrachyus, allied to Lophiodon, and to
Hyracodon an extinct form of rhinoceros. Besides these we have Lophiotherium
(also from the Eocene of Europe); Diplacodon allied to Limnohyus, but with
affinities to modern Perissodactyla and nearly as large as a rhinoceros; and
Colonoceras, also belonging to the Limnohyidæ, an animal which was the size of a
sheep, and had divergent protuberances or horns on its nose. A remarkable genus,
Bathmodon, lately described by Professor Cope, and of which five species have
been found in the Eocene of New Mexico and Wyoming, is believed to form the
type of a new family, having some affinity to Palæosyops and to the extinct
Brontotheridæ. It had large canine tusks but no horns.

The Rhinocerotidæ are represented in America by the genus Rhinoceros in the
Pliocene and Miocene, and by Aceratherium and Hyracodon in the Miocene. Both
the latter were hornless, and Hyracodon was allied to the Eocene Hyrachyus, one
of the Lophiodontidæ. In the Eocene and Miocene deposits of Utah, and Oregon,
several remarkable extinct rhinoceroses have been recently discovered, forming
the genus Diceratherium. These had a pair of nasal horns placed side by side on
the snout, not behind each other as in existing two-horned rhinoceroses, the rest of
their skeleton resembling the hornless Aceratherium. They were of rather small
size.

Next to these extinct rhinoceroses come the Brontotheridæ, an extraordinary
family of large mammalia, some of which exceeded in bulk the largest living
rhinoceros. They had four toes to the front and three to the hind feet, with a pair of
large divergent horns on the front of the head, in both sexes. Professor Marsh and
Dr. Leidy have described four genera, Brontotherium, Titanotheium, Megacerops,
and Anisacodon, distinguished by peculiarities of dentition. Though most nearly
allied to the rhinoceroses, they show some affinity for the gigantic Dinocerata of
the Eocene to be noticed further on. Professor Cope has since described another
genus, Symborodon, from the Miocene of Colorado, with no less than seven
species, one nearly the size of an elephant. He thinks they had a short tapir-like
proboscis. The species differ greatly in the form of the cranium and development
of the horn-bearing processes.

We commence the Artiodactyla, or even-toed Ungulates, with the hog tribe. These
are represented by species of peccaries, (Dicotyles) from the Pliocene of Nebraska
and Oregon; and by an allied form Thinohyus, very like Dicotyles, but having an
additional premolar tooth and a much smaller brain-cavity. From the Miocene are

three allied genera, Nanohyus, Leptochœrus, and Perchœrus. Professor Cope,
however, thinks Leptochœrus may be Lemuroid, and allied to Menotherium. The
Anthracotheridæ, a family which connects the Hippopotamidæ and Ruminants,
and which occurs in the Miocene of Europe and India, are represented in America
by the genus Hyopotamus from the Miocene of Dakota, and Elotherium from the
Miocene of Oregon and the Eocene of Wyoming; the latter genus being sometimes
classed with the preceding family, and lately placed by Professor Marsh, in the
new order, Tillodontia. Professor Cope has since described three other genera from
the Eocene of New Mexico: Meniscotherium, having resemblances to Palæosyops,
Hyopotamus, and the Limnotheridæ; Phenacodus, the size of a hog, of doubtful
position, but perhaps near Elotherium; and Achænodon, as large as a cow, but more
hog-like than the preceding. Another new genus from the Miocene of Colorado—
Pelonax—is said by Professor Cope to come between Elotherium and
Hippopotamus.

The Camelidæ are very abundant, and form one of the most striking features of the
ancient fauna of America. Procamelus, Homocamelus, and Megalomeryx, are
extinct genera found in the Pliocene formation; the first very closely allied to the
Old World camel, the last smaller and more sheep-like. In the Miocene two other
genera occur, Pœbrotherium and Protomeryx, the former allied to both the camel
and the llama.

Deer are represented by a single species of Cervus in the Pliocene, while two
extinct genera, Leptomeryx and Merycodus, are found in the Miocene deposits, the
latter indicating a transition between camels and deer. Two other genera,
Hypisodus and Hypertragulus, of very small size, are said by Professor Cope to be
allied to the Tragulidæ and to Leptomeryx.

The Bovidæ, or hollow-horned ruminants, are only represented in the Newer
Pliocene by a single species of an extinct genus, Casoryx, said to be intermediate
between antelopes and deer.

We now come to an exclusively American family, the Oreodontidæ, which
consisted of small animals termed by Dr. Leidy, "ruminating hogs," and which had
some general structural resemblances to deer and camels. They abounded in North
America during the Pliocene, and especially during the Miocene epoch, no less
than six genera and twenty species having been discovered. Merychus contains the
Pliocene forms; while Oreodon, Eporeodon, Merychochœrus, Leptauchenia, and
Agriochœrus are Miocene. The last genus extends back into the Eocene period, and
shows affinity to the European Anoplotheridæ of the same epoch.

Proboscidea.—The Elephantidæ are only represented in America by one species of
Mastodon and one of Elephas, in the Newer Pliocene deposits. In the Older
Pliocene, Miocene, and Upper Eocene, no remains of this order have been found;
and in 1869, Dr. Leidy remarked on the small average size of the extinct North
American mammalia, which were almost all smaller than their living analogues.
Since then, however, wonderful discoveries have been made in deposits of Middle
Eocene age in Wyoming and Colorado, of a group of huge animals not only
rivalling the elephants in size, but of so remarkable and peculiar a structure as to
require the formation of a new order of mammals—Dinocerata—for their
reception.

This order consists of animals with generalised Ungulate and Proboscidean
affinities. The lower jaw resembles that of the hippopotamus; they had five toes on
the anterior feet and four on the posterior; three pairs of horns, the first pair on the
top of the head, large and perhaps palmated, the second pair above the eyes, while
the third and smallest stood out sideways on the snout. They had enormous upper
canines, of which the roots entered the middle horn cores, no upper incisors, and
small molars. Professor Marsh believes that they had no trunk. The remains
discovered indicate four genera, Dinoceras (3 sp.), Tinoceras (2 sp.), Uintatherium
(1 sp.), and Eobasileus (2 sp.). Many other names have been given to fragments of
these animals, and even those here given may not be all distinct.

Another new order, Tillodontia, recently established by Professor Marsh, is
perhaps yet more remarkable in a zoological point of view, since it combines the
characters of Carnivora, Ungulata, and Rodents. These animals have been formed
into two families, Tillotheridæ and Stylinodontidæ; and three genera, Tillotherium,
Anchippodus, and Stylinodontia. All are from the Eocene of Wyoming and New
Jersey. Perhaps to these must be added Elotherium from the Miocene of Dakota,
the other forms being all Eocene. They were mostly animals of small size, between
that of the capybara and tapir. The skull resembled in form that of a bear; the molar
teeth were of Ungulate type, and the incisors like those of a Rodent; but the
skeleton was more that of the Ursidæ, the feet being plantigrade. Professor Cope
has since described three new genera from the Eocene of New Mexico, Ectoganus,
Calamodon, and Esthonyx, comprising seven species allied to Tillotherium and
Anchippodus, and having also relations, as Professor Cope believes, with the South
American Toxodontidæ.

Rodentia.—This order is represented in the Pliocene by a beaver, a porcupine, and
an American mouse (Hesperomys), all extinct species of living genera, the Hystrix
being an Old World type; and Professor Cope has recently described Panolax, a

new genus of hares from the Pliocene of New Mexico. The Miocene deposits have
furnished an extinct genus allied to the hares—Palæolagus; one of the squirrel
family—Ischyromys; a small extinct form of beaver—Palæocastor; and an extinct
mouse—Eumys. The Eocene strata of Wyoming have lately furnished two extinct
forms of squirrel, Paramys and Sciuravus; and another of the Muridæ (or mouse
family), Mysops.

Cetacea.—Numerous remains of dolphins and whales, belonging to no less than
twelve genera, mostly extinct, have been found in the Miocene deposits of the
Atlantic and Gulf States, from New Jersey to South Carolina and Louisiana; while
seven genera of the extinct family, Zeuglodontidæ, have been found in Miocene
and Eocene beds of the same districts. Some remains associated with these are
doubtfully referred to the Seal family (Phocidæ) among the Carnivora.

Edentata.—Till quite recently no remains of this order have occurred in any North
American deposits below the Post-Pliocene; but in 1874 Prof. Marsh described
some remains allied to Megalonyx and Mylodon, from the Pliocene beds of
California and Idaho, and forming a new genus, Morotherium. As these remains
have only occurred to the west of the Rocky Mountains, and in Pliocene deposits
whose exact age is not ascertained, they hardly affect the remarkable absence of
this group from the whole of the exceedingly rich Tertiary deposits in all other
parts of North America.

General Relations of the extinct Tertiary Mammalia of North America and Europe.
—Having now given a sketch of the extinct Mammalia which inhabited Europe
and North America during the Tertiary period, we are enabled by comparing them,
to ascertain their relations to each other, and to see how far they elucidate the
problem of the birth-place and subsequent migrations of the several families and
genera. We have already pointed out the remarkable features of the Quaternary (or
Post-Pliocene) fauna of North America, and now proceed to discuss that of the
various Tertiary periods, which is closely connected with the extinct fauna of
Europe.

The Tertiary Mammalia of North America at present described belong to from
eighty to one hundred genera, while those of Europe are nearly double that
number; yet only eighteen genera are common to the two faunas, and of these eight
are living and belong chiefly to the Pliocene period. Taking first, the genera which

in America do not go back beyond the Pliocene period (ten in number), we find
that eight of them in Europe go back to the Upper Miocene. These are Felis,
Pseudælurus, Hipparion, Cervus, Mastodon, Elephas (in India), Castor and
Hystrix; while another, Canis, goes back to the Upper Eocene and the tenth, Equus,
confined to the newer Pliocene or perhaps to the Post-Pliocene in America, extends
back to the older Pliocene in Europe. Of the seven European genera which are
confined to the Miocene period in America, three, Hyænodon, Anchitherium, and
Lophiodon go back to the Eocene in Europe; three others, Machairodus,
Rhinoceros, and Aceratherium, are also of Miocene age in Europe; Amphicyon
goes back to the Lower Miocene of Europe. Lophiotherium belongs to the Eocene
of both countries.

If we turn now to families instead of genera, we find that the same general rule
prevails. Mustelidæ (weasels), Ursidæ (bears), true Equidæ (horses), and Bovidæ
(oxen &c.), go no further back in America than the Pliocene, while they all go back
to the Miocene in Europe. Suidæ (swine) and Anoplotheridæ (extinct) are found in
the American Miocene and in the European Eocene. Anchitheridæ (extinct) reach
the Upper Eocene in America, while in Europe they range through Upper, Middle,
and Lower Eocene. Cervidæ (deer) alone are Miocene in both countries. There
remain two families in which America has the preeminence. Camelidæ (camels)
were wonderfully developed in the American Pliocene and Miocene periods,
abounding in genera and species; whereas in Europe the group only exists in the
Post-Pliocene or Lower Pliocene, with one Upper Miocene species of Camelus in
N. India. The Anthracotheridæ (extinct), found only in the Upper Miocene of
France and India, reach even the Lower Eocene in America.

These facts may be due, in part, to a want of strict co-ordination between the
Tertiary deposits of Europe and North America,—in part to the imperfection of the
record in the latter country. Yet it does not seem probable that they are altogether
due South America and well marked differences to imperfect knowledge; yet we
find such important families as the Civets, Hyænas, Giraffes, and Hippopotami
absent from America, with the Weasels, and Antelopes almost so; while America
possesses almost all the Camelidæ, two peculiar orders, Dinocerata and
Tillodontia, and four remarkably peculiar families, Limnotheridæ, Lemuravidæ,
Oreodontidæ and Brontotheridæ. If then the facts at present known represent
approximately the real time-relations of the groups in question on the two
continents, they render it probable that weasels, bears, true horses, swine, oxen,
sheep and antelopes, originated on the Old World continent, and were transmitted
to America during some part of the Miocene period; while camels originated in the
New World, and somewhere about the same time passed over to Europe. Of the

extinct families common to the two hemispheres, the Anthracotheridæ alone seem
to have had an American origin. Of the genera common to the two countries,
almost all seem to have had a European origin, the only genera of equal date being
the two rhinoceroses and three Anchitheridæ; but if the Brontotheridæ are allied to
the Rhinocerotidæ, these latter may have originated in America, although now an
exclusively Old World type. These conclusions are not improbable when we
consider the much greater size of the Old World continents, extending far into the
tropics and probably always more or less united to the tropical areas; while the
evidence of the extinct mammalia themselves shows, that South America has been
for the most part isolated from the northern continent, and did not take part in the
development of its characteristic Tertiary fauna.

Before speculating further on this subject, it will be well to lay before our readers a
summary of South American palæontology, after which we shall be in a better
position to draw correct inferences from the whole body of the evidence.

South America.

Unfortunately, our knowledge of the interesting fossil fauna of this continent, is
almost wholly confined to the Post-Pliocene and Pliocene periods. A few remains
have been discovered in deposits believed to be of Eocene age, but nothing
whatever representing the vast intervening period, so rich in peculiar forms of
animal life both in North America and Europe.

Fauna of the Brazilian caves.—What we know of the Post-Pliocene period is
chiefly due to the long-continued researches of Dr. Lund in the caves of Central
Brazil, mostly situated in a district near the head waters of the San Francisco river
in the Province of Minas Geraes. The caves are formed in limestone rocks, and are
so numerous that Dr. Lund visited thousands, but only sixty contained bones in any
quantity. These caves have a floor of reddish earth, often crowded with bones. In
one experiment, half a cubic foot of this earth contained jaws of 400 opossums,
2,000 mice, besides remains of bats, porcupines and small birds. In another trial,
the whole of the earth in a cavern was carried out for examination, amounting to
6,552 firkins; and, from a calculation made by measured samples, it was estimated
to contain nearly seven millions of jaw-bones of cavies, opossums, porcupines, and
mice, besides small birds, lizards, and frogs. This immense accumulation is
believed to have been formed from the bodies of animals brought into the cavern
by owls; and, as these are unsocial birds, the quantity found implies an immense
lapse of time, probably some thousands of years. More than 100 species of

Mammalia, in all, were obtained in these caves. Some were living species or
closely allied to such; but the majority were extinct, and a considerable number,
about one-fourth, belonged to extinct genera, or genera not now inhabiting South
America. Stone implements and human remains were found in several of the caves
with extinct animals. The following enumeration of these remains is from the
corrected list of M. Gervais.

Primates.—Extinct species of Cebus, Callithrix, and Jacchus—South American
genera of monkeys; with an extinct genus, Protopithecus—an animal of large size
but belonging to the American family Cebidæ.

Chiroptera.—Species belonging to the South American Phyllostomidæ, and to two
South American genera of other families.

Carnivora.—Five species of Felis, some allied to living animals, others extinct; a
species of the widespread extinct genus Machairodus; and a small species referred
to Cynælurus, the genus containing the hunting leopard now found only in Africa
and India. Canidæ are represented by Canis and Icticyon (a living Brazilian species
of the latter genus), and the extinct genus Speothos. Mustelidæ are represented by
extinct species of the South American genera Mephitis and Galictis. Procyonidæ,
by a species of Nasua. Ursidæ, by Arctotherium, a genus closely resembling, if not
identical with, that containing the "spectacled bear" of Chili.

Ungulata.—Equus, Tapirus, Dicotyles, Auchenia, Cervus, Leptotherium, and
Antilope, are the cave-genera of this order. Equus and Antelope are particularly
interesting, as representing groups forming no part of existing South American
zoology; while the presence also of Leptotherium, an extinct genus of antelopes,
shows that the group was fairly represented in South America at this comparatively
recent period.

Proboscidea.—A species of Mastodon, found also in the Pliocene of La Plata,
represents this order.

Rodentia.—These abound. Dasyprocta, Cælogenys, Cavia, Kerodon, all living
genera of Caviidæ, are represented by extinct species. Cercolabes, the 'tree
porcupine' (Cercolabidæ) has two species, one as large as a peccary; Myopotamus,
Loncheres, Carterodon, are existing genera of spiny rats (Echimyidæ); and there
are two extinct genera of the same family, Lonchophorus and Phyllomys.
Lagostomus (Chinchillidæ), the viscacha of the Pampas, is represented by an

extinct species. There is also an extinct species of Lepus; several species of
Hesperomys and Oxymycterus; and a large Arvicola, a genus not living in South
America.

Edentata.—These, which constitute the great feature of the existing South
American fauna, were still more abundant and varied in the Cave period, and it is
remarkable that most of them are extinct genera. The armadillos are alone
represented by living forms, Dasypus, and Xenurus; Eurydon and Heterodon, are
extinct genera of the same family, as well as Chlamydotherium—huge armadillos
the size of a tapir or rhinoceros, and Pachytherium, which was nearly as large. The
ant-eaters are represented only by Glossotherium, an extinct form allied to
Myrmecophaga and Manis. The sloths were more numerous, being represented by
the extinct genera Cælodon, Sphenodon and Ochotherium, the last of large size.
The huge terrestrial sloths—Megatheridæ, also abounded; there being species of
Megatherium and Megalonyx, as well as the allied Scelidotherium, supposed to
have some affinity for the African Orycteropus.

Marsupials.—No new forms of these appear, but numerous species of Didelphys,
all closely allied to opossums still living in South America.

The preceding sketch of the wonderful cave fauna of Central Brazil, is sufficient to
show that it represents, in the main, a period of great antiquity. Not only are almost
the whole of the species extinct, but there are twenty extinct genera, and three
others not now inhabitants of South America. The fact that so few remains of the
living animals of the country are found in these caves, indicates that some change
of physical conditions has occurred since they were the receptacles of so many of
the larger animals; and the presence of many extinct genera of large size,
especially among the Edentata and American families of Rodents, are additional
proofs of a very high antiquity. Yet many of these cave animals are closely allied to
those which are found in North America in the Post-Pliocene deposits only, so that
we have no reason to suppose the cave-fauna to be of much earlier date. But the
great amount of organic change it implies, must give us an enlarged idea of the
vast periods of time, as measured by years, which are included in this, the most
recent of all geological epochs.

Pliocene Period of Temperate South America.—We have now to consider the
numerous remains of extinct animals found in various deposits in the Pampas, and
in Patagonia, and a few in Bolivia. The age of these is uncertain; but as they are
very similar to the cave-fauna, though containing a somewhat larger proportion of
extinct genera and some very remarkable new forms, they cannot be very much
older, and are perhaps best referred at present to the newer portion of the Pliocene
formation.

Carnivora.—The genus Machairodus or sabre-toothed tigers, represents the
Felidæ. There are several species of wolves (Canis); a weasel (Mustela); two bears
of the Brazilian cave-genus Arctotherium; and the extinct European genus
Hyænarctos.

Ungulata.—There are two species of Equus, found in the Pampas, Chili, and
Bolivia; two of Macrauchenia, an extraordinary extinct group allied to the tapir
and Palæotherium, but with the long neck, and general size of a camel. A second
species found on the highlands of Bolivia is much smaller.

A more recent discovery, in Patagonia, is the almost perfect series of teeth of a
large animal named Homalodontotherium; and which is believed by Professor
Flower, who has described it, to have been allied to Rhinoceros, and still more to
the Miocene Hyracodon from North America; and also to present some
resemblances to Macrauchenia, and though much more remotely, to the curious
genus Nesodon mentioned further on.

The Artiodactyla, or even-toed Ungulates, are represented by a species of
Dicotyles, or peccary, found in the deposits of the Pampas; by Auchenia, or llama,
of which three extinct species inhabited Bolivia, in which country two allied but
extinct genera, Palæolama and Camelotherium, have also been found. Three
species of deer (Cervus), from the Pampas deposits, complete the list of Pliocene
Ungulates.

Proboscidea.—The cave species of Mastodon is found also in the Pampas
deposits, and another in the Andes of Chili and Bolivia.

Rodents.—These are not so numerous as in the caves. There are species of the
existing genera, Kerodon and Cavia (Caviidæ); Lagostomus (Chinchillidæ);
Ctenomys (Octodontidæ); Lepus (hare); Hesperomys and Oxymycterus (Muridæ);
Arvicola, a genus not living in South America; and an extinct genus, Cardiodus.

There is also a remarkable extinct form, Typotherium, larger than the capybara, and
having affinities to Edentates and Ungulates. Three species have been found in the
Pampas deposits.

Edentata.—These are as abundant and remarkable as in the cave deposits.
Scelidotherium, Megatherium, Megalonyx, Glossotherium and Dasypus, have
already been noticed as from the Brazilian caves. We have here, in addition, the
huge Mylodon allied to the Megatherium, and the allied genera—Gnathopsis and
Lestodon. We then come to the huge extinct armadillos, Glyptodon and
Schistopleurum, the former consisting of numerous species, some of which were as
large as an elephant. Another genus, Eutatus, is allied to the living three-banded
armadillos; and a species of the existing genus Euphractus has been found in
Bolivia.

Toxodontidæ.—There remain a number of huge animals rivalling the Megatherium
in size, and forming the genera Toxodon and Nesodon, but whose position is
doubtful. Several species have been found in the deposits of the Pampas and
Patagonia. They are allied at once to Ungulates, Rodents, Edentates, and the
aquatic Sirenia, in so puzzling a manner that it is impossible to determine to what
order they belong, or whether they require a new order to be formed for their
reception. Some are believed to date back to the Miocene period, and they indicate
what strange forms may still be discovered, should any productive deposits be
found in South America of middle Tertiary age.

Pliocene Mammalia of the Antilles.—These may be noticed here, as they are of
special interest, proving the connection of the larger West Indian Islands with the
Continent some time in the later Tertiary period. They consist of remains of two
large animals belonging to the South American Chinchillidæ, found in cave
deposits in the island of Anguilla, and forming two new genera, Amblyrhiza and
Loxomylus; and remain allied to Megalonyx from Cuba, which have been named
Megalocnus and Myomorphus.

Eocene fauna of South America.—The few remains yet discovered in the Tertiary
deposits of the Pampas which are believed to be of Eocene age, are exceedingly
interesting, because they show us another change in the scenery of the great drama
of life; there being apparently a considerable resemblance, at this epoch, between
South America and Europe. They consist of a large extinct feline animal,

Eutemnodus; of Palæotherium and Anoplotherium, the well-known extinct
Ungulates of the European Tertiaries, and which have never been found in North
America; and of three genera of Rodents,—Theridromys, allied to Echimys, and
found also in the Eocene and Miocene of France; Megamys, allied to the living
Capromys of the Antilles, and also to Palæomys, an extinct form of the French
Miocene; and a very large animal referred to Arvicola, a genus found also in the
Pliocene deposits of South America, and abundant in the northern hemisphere. No
Edentates have been found.

The resemblances of this fauna to that of Europe rather than to any part of
America, are so strong, that they can hardly be accidental. We greatly want,
however, more information on this point, as well as some corresponding evidences
as to the condition of West and South Africa about the same epoch, before we can
venture to speculate on their bearing as regards the early migrations of organic
forms.

General Remarks on the Extinct Mammalian Fauna of the Old and New Worlds.—
Leaving the more special applications of palæontological evidence to be made
after discussing the relations of the existing fauna of the several regions, we
propose here to indicate briefly, some of the more general deductions from the
evidence which has now been laid before our readers.

The first, and perhaps the most startling fact brought out by our systematic review,
is the very recent and almost universal change that has taken place in the character
of the fauna, over all the areas we have been considering; a change which seems to
be altogether unprecedented in the past history of the same countries as revealed
by the geological record. In Europe, in North America, and in South America, we
have evidence that a very similar change occurred about the same time. In all three
we find, in the most recent deposits—cave-earths, peat-bogs, and gravels—the
remains of a whole series of large animals, which have since become wholly
extinct or only survive in far-distant lands. In Europe, the great Irish elk, the
Machairodus and cave-lion, the rhinoceros, hippopotamus, and elephant;—in
North America, equally large felines, horses and tapirs larger than any now living,
a llama as large as a camel, great mastodons and elephants, and abundance of huge
megatheroid animals of almost equal size;—in South America these same
megatheroids in greater variety, numerous huge armadillos, a mastodon, large
horses and tapirs, large porcupines, two forms of antelope, numerous bears and
felines, including a Machairodus, and a large monkey,—have all become extinct

since the deposition of the most recent of the fossil-bearing strata. This is certainly
not a great while ago, geologically; and it is almost certain that this great organic
revolution, implying physical changes of such vast proportions that they must have
been due to causes of adequate intensity and proportionate range, has taken place
since man lived on the earth. This is proved to have been the case in Europe, and is
supported by much evidence both as regards North and South America.

It is clear that so complete and sudden a change in the higher forms of life, does
not represent the normal state of things. Species and genera have not, at all times,
become so rapidly extinct. The time occupied by the "Recent period," that is the
time since these changes took place is, geologically, minute. The time of the whole
of the Post-Pliocene period, as measured by the amount of physical and general
organic change known to have taken place, is exceedingly small when compared
with the duration of the Pliocene period, and still smaller, probably, as compared
with the Miocene. Yet during these two periods we meet with no such break in the
continuity of the forms of life, no such radical change in the character of the fauna
(though the number of specific and generic changes may be as great) as we find in
passing from the Post-Pliocene to recent times. For example, in Central Europe
numerous hyænas, rhinoceroses, and antelopes, with the great Machairodus,
continued from Miocene all through Pliocene into Post-Pliocene times; while
hippopotami and elephants continued to live through a good part of the Pliocene
and Post-Pliocene periods,—and then all suddenly became extinct or left the
country. In North America there has been more movement of the fauna in all the
periods; but we have similar great felines, horses, mastodons, and elephants, in the
Pliocene and Post-Pliocene periods, while Rhinoceros is common to the Miocene
and Pliocene, and camels range continuously from Miocene, through Pliocene, to
Post-Pliocene times;—when all alike became extinct. Even in South America the
evidence is, as far as it goes, all the same way. We find Machairodus, Equus,
Mastodon, Megatherium, Scelidotherium, Megalonyx, and numerous gigantic
armadillos, alike in the caves and in the stratified tertiary deposits of the Pampas;
—yet all have since passed away.

It is clear, therefore, that we are now in an altogether exceptional period of the
earth's history. We live in a zoologically impoverished world, from which all the
hugest, and fiercest, and strangest forms have recently disappeared; and it is, no
doubt, a much better world for us now they have gone. Yet it is surely a marvellous
fact, and one that has hardly been sufficiently dwelt upon, this sudden dying out of
so many large mammalia, not in one place only but over half the land surface of
the globe. We cannot but believe that there must have been some physical cause
for this great change; and it must have been a cause capable of acting almost

simultaneously over large portions of the earth's surface, and one which, as far as
the Tertiary period at least is concerned, was of an exceptional character. Such a
cause exists in the great and recent physical change known as "the Glacial epoch."
We have proof in both Europe and North America, that just about the time these
large animals were disappearing, all the northern parts of these continents were
wrapped in a mantle of ice; and we have every reason to believe that the presence
of this large quantity of ice (known to have been thousands of feet if not some
miles in thickness) must have acted in various ways to have produced alterations
of level of the ocean as well as vast local floods, which would have combined with
the excessive cold to destroy animal life. There is great difference of opinion
among geologists and physicists as to the extent, nature, and duration of the
Glacial epoch. Some believe it to have prevailed alternately in the northern and
southern hemispheres; others that it was simultaneous in both. Some think there
was a succession of cold periods, each lasting many thousands of years, but with
intercalated warm periods of equal duration; others deny that there is any evidence
of such changes, and maintain that the Glacial epoch was one continuous period of
arctic conditions in the temperate zones, with some fluctuations perhaps but with
no regular alternations of warm periods. Some believe in a huge ice-cap covering
the whole northern hemisphere from the pole to near 50° north latitude in the
eastern, and 40° in the western hemisphere; while others impute the observed
effects either to glaciers from local centres, or to floating icebergs of vast size
passing over the surface during a period of submersion.

Without venturing to decide which of these various theories will be ultimately
proved to be correct, we may state, that there is an increasing belief among
geologists in the long duration of this ice-period, and the vast extent and great
thickness attained by the ice-sheet. One of the most recent, and not the least able,
of the writers on this question (Mr. Belt) shows strong reasons for adopting the
view that the ice-period was simultaneous in both hemispheres; and he calculates
that the vast amount of water abstracted from the ocean and locked up in
mountains of ice around the two poles, would lower the general level of the ocean
about 2,000 feet. This would be equivalent to a general elevation of the land to the
same amount, and would thus tend to intensify the cold; and this elevation may
enable us to understand the recent discoveries of signs of glacial action at
moderate elevations in Central America and Brazil, far within the tropics. At the
same time, the weight of ice piled up in the north would cause the land surface to
sink there, perhaps unequally, according to the varying nature of the interior crust
of the earth; and since the weight has been removed land would rise again, still
somewhat irregularly; and thus the phenomena of raised beds of arctic shells in
temperate latitudes, are explained.

Now, it is evident, that the phenomena we have been considering—of the recent
changes of the mammalian fauna in Europe, North America, South Temperate
America, and the highlands of Brazil—are such as might be explained by the most
extreme views as to the extent and vastness of the ice-sheet, and especially as to its
simultaneous occurrence in the northern and southern hemispheres; and where two
such completely independent sets of facts are found to combine harmoniously, and
supplement each other on a particular hypothesis, the evidence in favour of that
hypothesis is greatly strengthened. An objection that will occur to zoologists, may
here be noticed. If the Glacial epoch extended over so much of the temperate and
even parts of the tropical zone, and led to the extinction of so many forms of life
even within the tropics, how is it that so much of the purely tropical fauna of South
America has maintained itself, and that there are still such a vast number of forms,
both of mammalia, birds, reptiles, and insects, that seem organized for an exclusive
existence in tropical forests? Now Mr. Belt's theory, of the subsidence of the ocean
to the extent of about 2,000 feet, supplies an answer to this objection; for we
should thus have a tract of lowland of an average width of some hundreds of miles,
added to the whole east coast of Central and South America. This tract would, no
doubt, become covered with forests as it was slowly formed, would enjoy a
perfectly tropical climate, and would thus afford an ample area for the continued
existence and development of the typical South American fauna; even had glaciers
descended in places so low as what is now the level of the sea, which, however,
there is no reason to believe they ever did. It is probable too, that this low tract,
which all round the Gulf of Mexico would be of considerable width, offered that
passage for intermigration between North and South America, which led to the
sudden appearance in the former country in Post-Pliocene times, of the huge
Megatheroids from the latter; a migration which took place in opposite directions
as we shall presently show.

The birth-place and migrations of some mammalian families and genera.—We
have now to consider a few of those cases in which the evidence already at our
command, is sufficiently definite and complete, to enable us to pronounce with
some confidence as to the last movements of several important groups of
mammalia.

Primates.—The occurrence in North America of numerous forms of Lemuroidea,
forming two extinct families, which are believed by American palæontologists to
present generalized features of both Lemuridæ and Hapalidæ, while in Europe only
Lemurine forms allied to those of Africa have occurred in deposits of the same age
(Eocene), renders it possible that the Primates may have originated in America,
and sent one branch to South America to form the Hapalidæ and Cebidæ, and

another to the Old World, giving rise to the lemurs and true apes. But the fact that
apes of a high degree of organization occur in the European Miocene, while in the
Eocene, a monkey believed to have relations to the Lemuroids and Cebidæ has
also been discovered, make it more probable that the ancestral forms of this order
originated in the Old World at a still earlier period. The absence of any early
tertiary remains from the tropical parts of the two hemispheres, renders it
impossible to arrive at any definite conclusions as to the origin of groups which
were, no doubt, always best developed in tropical regions.

Carnivora.—This is a very ancient and wide-spread group, the families and genera
of which had an extensive range in very early times. The true bears (Ursus) are
almost the only important genus that seems to have recently migrated. In Europe it
dates back to the Older Pliocene, while in North America it is Post-Pliocene only.
Bears, therefore, seem to have passed into America from the Palæarctic region in
the latter part of the Pliocene period. They probably came in on the north-west, and
passed down the Andes into South America, where one isolated species still exists.

Ungulata.—Horses are very interesting. In Europe they date back under various
forms to the Miocene period, and true Equus to the Older Pliocene. In North
America they are chiefly Pliocene, true Equus being Post-Pliocene, with perhaps
one or two species Newer Pliocene; but numerous ancestral forms date back to the
Miocene and Eocene, giving a more perfect "pedigree of the horse" than the
European forms, and going back to a more primitive type—Orohippus. In South
America, Equus is the only genus, and is Post-Pliocene or at most Newer Pliocene.
While, therefore, the ancient progenitors of the Equidæ were common to North
America and Europe, in Miocene and even Eocene times, true horses appear to
have arisen in the Palæarctic region, to have passed into North America in the
latter part of the Pliocene period, and thence to have spread over all suitable
districts in South America. They were not, however, able to maintain themselves
permanently in their new territory, and all became extinct; while in their birth-
place, the Old World, they continue to exist under several varied forms.

True tapirs are an Old World group. They go back to the Lower Miocene in
Europe, while in both North and South America they are exclusively Post-
Pliocene. They occur in France down to the Newer Pliocene, and must, about that
time, have entered America. The land connection by which this and so many other
animals passed between the Old and New Worlds in late Tertiary times, was almost
certainly in the North Pacific, south of Behring's Straits, where, as will be seen by
our general map, there is a large expanse of shallow water, which a moderate
elevation would convert into dry land, in a sufficiently temperate latitude.

The peccary (Dicotyles), now a characteristic South American genus, is a recent
immigrant from North America, where it appears to have been developed from
ancestral forms of swine dating back to the Miocene period.

Antelopes are an Old World type, but a few of them appear to have entered North,
and reached South America in late Pliocene times. Camels, strange to say, are a
special North American type, since they abounded in that continent under various
ancient forms in the Miocene period. Towards the end of that period they appear to
have entered eastern Asia, and developed into the Siberian Merycotherium and the
North Indian Camelus, while in the Pliocene age the ancestral llamas entered
South America.

Cervidæ are a wide-spread northern type in their generalized form, but true deer
(Cervus) are Palæarctic. They abounded in Europe in Miocene times, but only
appear in North and South America in the later Pliocene and Post-Pliocene periods.

True oxen (Bovinæ) seem to be an Oriental type (Miocene), while they appear in
Europe only late in the Pliocene period, and in America are confined to the Post-
Pliocene.

Elephants (Elephantidæ) are an Old World type, abounding in the Miocene period
in Europe and India, and first appearing in America in Post-Pliocene or later
Pliocene times. Ancestral forms, doubtfully Proboscidean (Dinocerata), existed in
North America in the Eocene period, but these became extinct without leaving any
direct descendants, unless the Brontotheridæ and rhinoceroses may be so
considered.

Marsupials are almost certainly a recent introduction into South and North
America from Asia. They existed in Europe in Eocene and Miocene times, and
presumably over a considerable part of the Old World; but no trace of them
appears in North or South America before the Post-Pliocene period.

Edentata.—These offer a most curious and difficult problem. In South America
they abound, and were so much more numerous and varied in the Post-Pliocene
and Pliocene, that we may be sure they lived also in the preceding Miocene period.
A few living Edentates are scattered over Africa and Asia, and they flourished in
Europe during the Miocene age—animals as large (in some species) as a
rhinoceros, and most allied to living African forms. In North America no trace of
Edentata has been found earlier than the Post-Pliocene period, or perhaps the

Newer Pliocene on the west coast. Neither is there any trace of them in South
America in the Eocene formations; but this may well be owing to our very
imperfect knowledge of the forms of that epoch. Their absence from North
America is, however, probably real; and we have to account for their presence in
the Old World and in South America. Their antiquity is no doubt very great, and
the point of divergence of the Old World and South American groups, may take us
back to early Eocene, or even to Pre-Eocene times. The distribution of land and sea
may then have been very different from what it is now; and to those who would
create a continent to account for the migrations of a beetle, nothing would seem
more probable than that a South Atlantic continent, then united parts of what are
now Africa and South America. There is, however, so much evidence for the
general permanence of what are now the great continents and deep oceans, that
Professor Huxley's supposition of a considerable extension of land round the
borders of the North Pacific Ocean in Mesozoic times, best indicates the probable
area in which the Edentate type originated, and thence spread over much of the
Old World and South America. But while in the latter country it flourished and
increased with little check, in the other great continents it was soon overcome by
the competition of higher forms, only leaving a few small-sized representatives in
Africa and Asia.

CHAPTER VIII.

VA R I O U S E X T I N C T A N I M A L S ; — A N D O N T H E A N T I Q U I T Y O F T H E
GENERA OF INSECTS AND LAND MOLLUSCA.

EXTINCT MAMMALIA OF AUSTRALIA.

These have all been obtained from caves and late Tertiary or Post-Tertiary
deposits, and consist of a large number of extinct forms, some of gigantic size, but
all marsupials and allied to the existing fauna. There are numerous forms of
kangaroos, some larger than any living species; and among these are two genera,
Protemnodon and Sthenurus, which Professor Garrod has lately shown to have
been allied, not to any Australian forms, but to the Dendrolagi or tree-kangaroos of
New Guinea. We have also remains of Thylacinus and Dasyurus, which now only
exist in Tasmania; and extinct species of Hypsiprymnus and Phascolomys, the
latter as large as a tapir. Among the more remarkable extinct genera are
Diprotodon, a huge thick-limbed animal allied to the kangaroos, but nearly as large
as an elephant; Nototherium, having characters of Macropus and Phascolarctos
combined, and as large as a rhinoceros; and Thylacoleo, a phalanger-like marsupial
nearly as large as a lion, and supposed by Professor Owen to have been of
carnivorous habits, though this opinion is not held by other naturalists.

Here then we find the same phenomena as in the other countries we have already
discussed,—the very recent disappearance of a large number of peculiar forms,
many of them far surpassing in size any that continue to exist. It hardly seems
probable that in this case their disappearance can have been due to the direct
effects of the Glacial epoch, since no very extensive glaciation could have
occurred in a country like Australia; but if the ocean sank 2,000 feet, the great
eastern mountain range might have given rise to local glaciers. It is, however,
almost certain that during late Tertiary times Australia must have been much more
extensive than it is now. This is necessary to allow of the development of its
peculiar and extensive fauna, especially as we see that that fauna comprised
animals rivalling in bulk those of the great continents. It is further indicated by the
relations with New Guinea, already alluded to, and by the general character of the
various faunas which compose the Australian region, details of which will be
found in the succeeding part of this work. The lowering of the ocean during the
Glacial period would be favourable to the still further development of the fauna of
such a country; and it is to the unfavourable conditions produced by its subsequent
rising—equivalent to a depression of the land to the amount of two thousand feet
—that we must impute the extinction of so many remarkable groups of animals. It
is not improbable, that the disappearance of the ice and the consequent (apparent)

subsidence of the land, might have been rapid as compared with the rate at which
large animals can become modified to meet new conditions. Extensive tracts of
fertile land might have been submerged, and the consequent crowding of large
numbers of species and individuals on limited areas would have led to a struggle
for existence in which the less adapted and less easily modifiable, not the
physically weaker, would succumb.

There is, however, another cause for the extinction of large rather than small
animals whenever an important change of conditions occurs, which has been
suggested to me by a correspondent,[4] but which has not, I believe, been adduced
by Mr. Darwin or by any other writer on the subject. It is dependent on the fact,
that large animals as compared with small ones are almost invariably slow
breeders, and as they also necessarily exist in much smaller numbers in a given
area, they offer far less materials for favourable variations than do smaller animals.
In such an extreme case as that of the rabbit and elephant, the young born each
year in the world are probably as some millions to one; and it is very easily
conceivable that in a thousand years the former might, under pressure of rapidly
changing conditions, become modified into a distinct species, while the latter, not
offering enough favourable variations to effect a suitable adaptation, would
become extinct. We must also remember the extreme specialization of many of the
large animals that have become extinct—a specialization which would necessarily
render modification in any new direction difficult, since the inherited tendency of
variation would probably be to increase the specialization in the same directions
which had heretofore been beneficial. If to these two causes we add the difficulty
of obtaining sufficient food for such large animals, and perhaps the injurious
effects of changes of climate, we shall not find it difficult to understand how such
a vast physical revolution as the Glacial epoch, with its attendant phenomena of
elevations and subsidences, icy winds, and sudden floods by the bursting of lake
barriers, might have led to the total extinction of a vast number of the most bulky
forms of mammalia, while the less bulky were able to survive, either by greater
hardiness of constitution or by becoming more or less modified. The result is
apparent in the comparatively small or moderate size of the species constituting the
temperate fauna, in all parts of the globe.

It is much to be regretted that no mammalian remains of earlier date have been
found in Australia, as we should then see if it is really the case that marsupials
have always formed its highest type of mammalian life. At present its fossil fauna
is chiefly interesting to the zoologist, but throws little light on the past relations of
this isolated country with other parts of the globe.

Mammalian remains in the Secondary Formations.

In the oldest Tertiary beds of Europe and North America, we have (even with our
present imperfect record) a rich and varied mammalian fauna. As compared with
our living or recent highly specialized forms, it may be said to consist of
generalised types; but as compared with any primeval mammalian type, it must be
pronounced highly specialised. Not only are such diversified groups as Carnivora,
Perrissodactyle and Artiodactyle Ungulates, Primates, Chiroptera, Rodents, and
Marsupials already well marked, but in many of these there is a differentiation into
numerous families and genera of diverse character. It is impossible therefore to
doubt, that many peculiar forms of mammalia must have lived long anterior to the
Eocene period; but there is unfortunately a great gap in the record between the
Eocene and Cretaceous beds, and these latter being for the most part marine
continue the gap as regards mammals over an enormous lapse of time. Yet far
beyond both these chasms in the Upper Oolitic strata, remains of small mammalia
have been found; again, in the Stonesfield slate, a member of the Lower Oolite,
other forms appear. Then comes the marine Lias formation with another huge gap;
but beyond this again in the Upper Trias, the oldest of the secondary formations,
mammalian teeth have been discovered in both England and Germany, and these
are, as nearly as can be ascertained, of the same age as the Dromatherium already
noticed, from North America. They have been named Microlestes, and show some
resemblance to those of the West Australian Myrmecobius. In the Oolitic strata
numerous small jawbones have been found, which have served to characterise
eight genera, all of which are believed to have been Marsupials, and in some of
them a resemblance can be traced to some of the smaller living Australian species.
These, however, are mere indications of the number of mammalia that must have
lived in the secondary period, so long thought to be exclusively "the age of
reptiles;" and the fact that the few yet found are at all comparable with such
specialised forms as still exist, must convince us, that we shall have to seek far
beyond even the earliest of these remains, for the first appearance of the
mammalian type of vertebrata.

Extinct Birds.

Compared with those of mammalia, the remains of birds are exceedingly scarce in
Europe and America; and from the wandering habits of so many of this class, they
are of much less value as indications of past changes in physical geography. A
large proportion of the remains belong to aquatic or wading types, and as these
have now often a world-wide range, the occurrence of extinct forms can have little

bearing on our present inquiry. There are, however, a few interesting cases of
extinct land-birds belonging to groups now quite strangers to the country in which
they are found; and others scarcely less interesting, in which groups now peculiar
to certain areas are shown to have been preceded by allied species or genera of
gigantic size.

Palæarctic Region and N. India.—In the caves and other Post-Pliocene deposits of
these countries, the remains of birds almost all belong to genera now inhabiting the
same districts. Almost the only exceptions are, the great auk and the capercailzie,
already mentioned as being found in the Danish mounds; the latter bird, with
Tetrao albus, in Italian caverns; and a species of pheasant (Phasianus) said to have
occurred in the Post-Pliocene of France, considerably west of the existing range of
the genus in a wild state.

In the preceding Pliocene deposits, but few remains have been found, and all of
existing genera but one, a gallinaceous bird (Gallus bravardi) allied to the
domestic fowl and peacock.

The Miocene beds of France and Central Europe have produced many more
remains of birds, but these, too, are mostly of existing European genera, though
there are some notable exceptions. Along with forms undistinguishable from crows
(Corvus), shrikes (Lanius), wagtails (Motacilla), and woodpeckers (Picus), are
found remains allied to the Oriental edible-nest swift (Collocalia) and Trogon; a
parrot resembling the African genus Psittacus; an extinct form Necrornis, perhaps
allied to the plantain-eaters (Musophaga); Homalophus, doubtfully allied to
woodpeckers, and Limnatornis to the hoopoes. The gallinaceous birds are
represented by three species of pheasants, some very close to the domesticated
species; Palæoperdix allied to the partridges; and Palæortyx, small birds allied to
the American genus Ortyx, but with larger wings. There are also species of
Pterocles allied to living birds, and a small pigeon. There are numerous living
genera of Accipitres; such as eagle (Aquila), kite (Milvus), eagle-owl (Bubo), and
screech-owl (Strix); with the African secretary-bird (Serpentarius), and some
extinct forms, as Palæocercus, Palæohierix and Palæetus.

Aquatic and wading birds were abundant, including numerous rails, bustards,
herons, sandpipers, gulls, divers, and pelicans. There were also many ducks, some
allied to the genus Dendrocygna; the Oriental genus of storks, Leptoptilus;
Ibidipodia, a remarkable form allied to Ibis and Ciconia; Elornis, near Limosa;
Pelagornis, a large bird allied to gannets and pelicans; Hydrornis, allied to the
ducks and petrels; Dolichopterus, allied to plovers. Perhaps the most interesting of

these extinct birds are, however, the flamingoes, represented by forms hardly
distinguishable from living species, and by one extinct genus Palælodus, which
had very long toes, and probably walked on aquatic plants like the tropical jacanas.

The Miocene beds of North India have furnished few birds; the only one of
geographical interest being an extinct species of ostrich, not very different from
that now inhabiting Arabia.

On the whole, the birds of Europe at this period were very like those now living,
with the addition of a few tropical forms. These latter were, however, perhaps
more numerous and important than they appear to be, as they belong to inland and
forest-haunting types, which would not be so frequently preserved as the marsh
and lake-dwelling species. Taking this into consideration, the assemblage of
Miocene birds accords well with what we know of the mammalian fauna. We have
the same indications of a luxuriant vegetation and subtropical climate, and the
same appearance of Oriental and especially of African types. Trogon is perhaps the
most interesting of all the forms yet discovered, since it furnishes us with a central
point whence the living trogons of Asia, Africa, and South America might have
diverged.

In the Eocene we find ourselves almost wholly among extinct forms of birds. The
earliest known Passerine bird is here met with, in Protornis, somewhat similar to a
lark, found in the Lower Eocene of Switzerland; while another Passerine form,
Palægithalus, and one allied to the nuthatch (Sitta), have been discovered in the
Upper Eocene of Paris. Picariæ of equal antiquity are found. Cryptornis, from the
Paris Eocene, and Halcyornis from the Lower Eocene of the Isle of Sheppey, were
both allied to kingfishers; while a form allied to Centropus a genus of cuckoos, or,
as Milne-Edwards thinks, to the Madagascar Leptosomus, has been found in the
Upper Eocene of France. Several Accipitres of somewhat doubtful affinities have
been found in the same country; while Lithornis, from the Lower Eocene of the
Isle of Sheppey, was a small vulturine bird supposed to be allied to the American
group, Cathartes. Among the waders, some extinct forms of plovers have been
found, and a genus (Agnopterus), allied to the flamingoes; while there are many
swimming birds, such as pelicans, divers, and several extinct types of doubtful
affinities. Most intersting of all is a portion of a cranium discovered in the Lower
Eocene of Sheppey, and lately pronounced by Professor Owen to belong to a large
Struthious bird, allied to the New Zealand Dinornis and also perhaps to the ostrich.
Another gigantic bird is the Gastornis, from the Lower Eocene of Paris, which was
as large as an ostrich, but which is believed to have been a generalised type, allied
to wading and swimming birds as well as to the Struthiones.

Beyond this epoch we have no remains of birds in European strata till we come to
the wonderful Archæopteryx from the Upper Oolite of Bavaria; a bird of a totally
new type, with a bony tail, longer than the body, each vertebra of which carried a
pair of diverging feathers.

North America.—A number of bird-remains have lately been found in the rich
Tertiary and Cretaceous deposits of the United States; but here, too, comparatively
few are terrestrial forms. No Passerine bird has yet been found. The Picariæ are
represented by Uintornis, an extinct form allied to woodpeckers, from the Eocene
of Wyoming. Species of turkey (Meleagris) occur in the Post-Pliocene and as far
back as the Miocene strata, showing that this interesting type is a true denizen of
temperate North America. The other birds are, Accipitres; waders and aquatics of
existing genera; and a number of extinct forms of the two latter orders—such as,
Aletornis an Eocene wader; Palæotringa, allied to the sandpipers, and Telmatobius
to the rails, both Cretaceous; with Graculavus, allied to Graculus; Laornis allied to
the swans; Hesperornis a gigantic diver; and Icthyornis a very low form, with
biconcave vertebra, such as are only found in fishes and some reptiles—also from
Cretaceous deposits.

South America.—The caverns of Brazil produced thirty-four species of birds, most
of them referable to Brazilian genera, and many to still existing species. The most
interesting were two species of American ostrich (Rhea), one larger than either of
the living species; a large turkey-buzzard (Cathartes); a new species of the very
isolated South American genus Opisthocomus; and a Cariama, or allied new
genus.

Madagascar and the Mascarene Islands.—We have here only evidence of birds
that have become extinct in the historical period or very little earlier. First we have
a group of birds incapable of flight, allied to pigeons, but forming a separate
family, Dididæ; and which, so far as we yet know, inhabited Mauritius, Rodriguez,
and probably Bourbon. Aphanapteryx, an extinct genus of rails, inhabited
Mauritius; and another genus, (Erythromachus), Rodriguez. A large parrot, said by
Prof. Milne Edwards to be allied to Ara and Microglossus, also inhabited
Mauritius; and another allied to Eclectus, the island of Rodriguez. None of these
have been found in Madagascar; but a gigantic Struthious bird, Æpyornis, forming
a peculiar family distinct both from the ostriches of Africa and the Dinornis of
New Zealand inhabited that island; and there is reason to believe that this may
have lived less than 200 years ago.

New Zealand.—A number of extinct Struthious birds, forming two families,
Dinornithidæ and Palapterygidæ, have been found in New Zealand. Some were of
gigantic size. They seem allied both to the living Apteryx of New Zealand and the
emu of Australia. They are quite recent, and some of them have probably lived
within the last few centuries. Remains of Dinornis have also been found in a Post-
Pliocene deposit in Queensland, N. E. Australia[5]—a very important discovery, as
it gives support to the theory of a great eastward extension of Australia in Tertiary
times.

Extinct Tertiary Reptiles.

These will not occupy us long, as no very great number are known, and most of
them belong to a few principal forms of comparatively little geographical interest.

Tortoises are perhaps the most abundant of the Tertiary reptiles. They are
numerous in the Eocene and Miocene formations both in Europe and North
America. The genera Emys and Trionyx abound in both countries, as well as in the
Miocene of India. Land tortoises occur in the Eocene of North America and in the
Miocene of Europe and India, where the huge Colossochelys, twelve feet long, has
been found. In the Pliocene deposits of Switzerland the living American genus
Chelydra has been met with. These facts, together with the occurrence of a living
species in the Miocene of India, show that this order of reptiles is of great
antiquity, and that most of the genera once had a wider range than now.

Crocodiles, allied to the three forms now characteristic of India, Africa, and
America, have been found in the Eocene of our own country, and several species
of Crocodilus have occurred in beds of the same age in North America.

Lizards are very ancient, many small terrestrial forms occurring in all the Tertiary
deposits. A species of the genus Chamæleo is recorded from the Eocene of North
America, together with several extinct genera.

Snakes were well developed in the Eocene period, where remains of several have
been found which must have been from twelve to twenty feet long. An extinct
species of true viper has occurred in the Miocene of France, and one of the
Pythonidæ in the Miocene brown coal of Germany.

Batrachia occur but sparingly in a fossil state in the Tertiary deposits. The most
remarkable is the large Salamander (Andreas) from the Upper Miocene of
Switzerland, which is allied to the Menopoma living in North America. Species of
frog (Rana), and Palæophryus an extinct genus of toads, have been found in the
Miocene deposits of Germany and Switzerland.

Fresh water fish are almost unknown in the Tertiary deposits of Europe, although
most of the families and some genera of living marine fish are represented from
the Eocene downwards.

Antiquity of the Genera of Insects.

Fossil insects are far too rarely found, to aid us in our determination of difficult
questions of geographical distribution; but in discussing these questions it will be
important to know, whether we are to look upon the existing generic forms of
insects as of great or small antiquity, compared with the higher vertebrates; and to
decide this question the materials at our command are ample.

The conditions requisite for the preservation of insects in a fossil state are no doubt
very local and peculiar; the result being, that it is only at long intervals in the
geological record that we meet with remains of insects in a recognisable condition.
None appear to have been found in the Pliocene formation; but in the Upper
Miocene of Œninghen in Switzerland, associated with the wonderfully rich fossil
flora, are found immense quantities of insects. Prof. Heer examined more than
5,000 specimens belonging to over 800 species, and many have been found in
other localities in Switzerland; so that more than 1,300 species of Miocene insects
have now been determined. Most of the orders are represented, but the beetles
(Coleoptera) are far the most abundant. Almost all belong to existing genera, and
the majority of these genera now inhabit Europe, only three or four being
exclusively Indian, African, or American.

In the Lower Miocene of Croatia there is another rich deposit of insects, somewhat
more tropical in character, comprising large white-ants and dragon-flies differently
marked from any now inhabiting Europe. A butterfly is also well preserved, with
all the markings of the wings; and it seems to be a Junonia, a tropical genus,
though it may be a Vanessa, which is European, but the fossil most resembles
Indian species of Junonia.

The Eocene formations seem to have produced no insect remains; but they occur
again in the Upper Cretaceous at Aix-la-Chapelle, where two butterflies have been
found, Cyllo sepulta and Satyrites Reynesii, both belonging to the Satyridæ, and
the former to a genus now spread over Africa, India, and Australia.

A little earlier, in the Wealden formation of our own country, numerous insects
have been found, principally dragon flies (Libellula, Æshna); aquatic Hemiptera
(Velia Hydrometra); crickets, cockroaches, and cicadas, of familiar types.

Further back in the Upper Oolite of Bavaria—which produced the wonderful long-
tailed bird, Archæopteryx—insects of all orders have been found, including a moth
referred to the existing genus Sphinx.

In the Lower Oolite of Oxfordshire many fossil beetles have been found whose
affinities are shown by their names:—Buprestidium, Curculionidium, Blapsidium,
Melolonthidium, and Prionidium; a wing of a butterfly has also been found, allied
to the Brassolidæ now confined to tropical America, and named Palæontina
oolitica.

Still more remote are the insects of the Lias of Gloucestershire, yet they too can be
referred to well-known family types—Carabidæ, Melolonthidæ, Telephoridæ,
Elateridæ, and Curculionidæ, among beetles; Gryllidæ and Blattidæ among
Orthoptera; with Libellula, Agrion, Æshna, Ephemera, and some extinct genera.
When we consider that almost the only vertebrata of this period were huge Saurian
reptiles like the Icthyosaurus, Plesiosaurus, and Dinosaurus, with the flying
Pterodactyles; and that the great mass of our existing genera, and even families, of
fish and reptiles had almost certainly not come into existence, we see at once that
types of insect-form are, proportionately, far more ancient. At this remote epoch
we find the chief family types (the genera of the time of Linnæus) perfectly
differentiated and recognisable. It is only when we go further back still, into the
Palæozoic formations, that the insect forms begin to show that generalization of
type which renders it impossible to classify them in any existing groups. Yet even
in the coal formation of Nova Scotia and Durham, the fossil insects are said by
competent entomologists to be "allied to Ephemera," "near Blatta," "near
Phasmidæ;" and in deposits of the same age at Saarbrück near Trèves, a well-
preserved wing of a grasshopper or locust has been found, as well as a beetle
referred to the Scarabeidæ. More remarkable, however, is the recent discovery in
the carboniferous shales of Belgium, of the clearly-defined wing of a large moth
(Breyeria borinensis), closely resembling some of the Saturniidæ; so that we have
now all the chief orders of Insects—including those supposed to be the most

highly developed and the most recent—well represented at this very remote epoch.
Even the oldest insects, from the Devonian rocks of North America, can mostly be
classed as Neuroptera or Myriapoda, but appear to form new families.

We may consider it, therefore, as proved, that many of the larger and more
important genera of insects date back to the beginning of the Tertiary period, or
perhaps beyond it; but the family types are far older, and must have been
differentiated very early in the Secondary period, while some of them perhaps go
back to Palæozoic times. The great comparative antiquity of the genera is however
the important fact for us, and we shall have occasion often to refer to it, in
endeavouring to ascertain the true bearing of the facts of insect distribution, as
elucidating or invalidating the conclusions arrived at from a study of the
distribution of the higher animals.

Antiquity of the Genera of Land and Fresh-Water Shells.

The remains of land and fresh-water shells are not much more frequent than those
of insects. Like them, too, their forms are very stable, continuing unchanged
through several geological periods. In the Pliocene and Miocene formations, most
of the shells are very similar to living species, and some are quite identical. In the
Eocene we meet with ordinary forms of the genera Helix, Clausilia, Pupa,
Bulimus, Glandina, Cyclostoma, Megalostoma, Planorbis, Paludina and Limnæa,
some resembling European species, others more like tropical forms. A British
Eocene species of Helix is still living in Texas; and in the South of France are
found species of the Brazilian sub-genera Megaspira and Anastoma. In the
secondary formation no true land shells have been found, but fresh water shells are
tolerably abundant, and almost all are still of living forms. In the Wealden (Lower
Cretaceous) and Purbeck (Upper Oolite) are found Unio, Melania, Paludina,
Planorbis, and Limnæa; while the last named genus occurs even in the Lias.

The notion that land shells were really not in existence during the secondary period
is, however, proved to be erroneous by the startling discovery, in the Palæozoic
coal measures of Nova Scotia, of two species of Helicidæ, both of living genera—
Pupa vetusta, and Zonites priscus. They have been found in the hollow trunk of a
Sigillaria, and in great quantities in a bed full of Stigmarian rootlets. The most
minute examination detects no important differences of form or of microscopic
structure, between these shells and living species of the same genera! These
mollusca were the contemporaries of Labyrinthodonts and strange Ganoid fishes,
which formed almost the whole vertebrate fauna. This unexpected discovery

renders it almost certain, that numbers of other existing genera, of which we have
found no traces, lived with these two through the whole secondary period; and we
are thus obliged to assume as a probability, that any particular genus has lived
through a long succession of geological ages. In estimating the importance of any
peculiarities or anomalies in the geographical distribution of land shells as
compared with the higher vertebrates, we shall, therefore, have to keep this
possible, and even probable high antiquity, constantly in mind.

We have now concluded our sketch of Tertiary Palæontology as a preparation for
the intelligent study of the Geographical Distribution of Land Animals; and
however imperfectly the task has been performed, the reader will at all events have
been convinced that some such preliminary investigation is an essential and most
important part of our work. So much of palæontology is at present tentative and
conjectural, that in combining the information derived from numerous writers,
many errors of detail must have been made. The main conclusions have, however,
been drawn from as large a basis of facts as possible; and although fresh
discoveries may show that our views as to the past history of some of the less
important genera or families are erroneous, they can hardly invalidate our results
to any important degree, either as regards the intercommunications between
separate regions in the various geological epochs, or as to the centres from which
some of the more important groups have been dispersed.

PART III.

ZOOLOGICAL GEOGRAPHY:

A REVIEW OF THE CHIEF FORMS OF ANIMAL LIFE IN THE SEVERAL REGIONS AND SUB-REGIONS,
WITH THE INDICATIONS THEY AFFORD OF GEOGRAPHICAL MUTATIONS.

CHAPTER IX.

THE ORDER OF SUCCESSION OF THE REGIONS.—
C O S M O P O L I TA N G R O U P S O F A N I M A L S . — TA B L E S O F
DISTRIBUTION.

Having discussed, in our First Part, such general and preliminary matters as
are necessary to a proper comprehension of our subject; and having made
ourselves acquainted, in our Second Part, with the most important results of
Palæontology, we now come to our more immediate subject, which we
propose to treat first under its geographical aspect. Taking each of our six
regions in succession, we shall point out in some detail the chief zoological
features they present, as influenced by climate, vegetation, and other
physical features. We shall then treat each of the sub-regions by itself, as
well as such of the islands or other sub-divisions as present features of
special interest; endeavouring to ascertain their true relations to each other,
and the more important changes of physical geography that seem necessary
to account for their present zoological condition.

Order of Succession of the Regions.—We may here explain the reason for
taking the several regions in a different succession from that in which they
appear in the tabular or diagrammatic headings to each family, in the
Fourth, and concluding part of this work. It will have been seen, by our
examination of extinct animals (and it will be made still clearer during our
study of the several regions) that all the chief types of animal life appear to
have originated in the great north temperate or northern continents; while
the southern continents—now represented by South America, Australia, and
South Africa with Madagascar—have been more or less completely
isolated, during long periods, both from the northern continent and from
each other. These latter countries have, however, been subject to more or
less immigration from the north during rare epochs of approximation to, or
partial union with it. In the northern, more extensive, and probably more
ancient land, the process of development has been more rapid, and has
resulted in more varied and higher types; while the southern lands, for the
most part, seem to have produced numerous diverging modifications of the

lower grades of organization, the original types of which they derived either
from the north, or from some of the ancient continents in Mesozoic or
Palæozoic times. Hence those curious resemblances in the fauna of South
America, Australia, and, to a less extent, Madagascar, which have led to a
somewhat general belief that these distant countries must at one time or
other have been united; a belief which, after a careful examination of all the
facts, does not seem to the author of this work to be well founded. On the
other hand, there is the most satisfactory evidence that each southern region
has been more or less closely united (during the tertiary or later secondary
epoch) with the great northern continents, leading to numerous
resemblances and affinities in their productions.

In endeavouring to present at a glance in the most convenient manner, the
distribution of the families in the several regions and sub-regions, it was
necessary to arrange them, so that those whose relations to each other were
closest should stand side by side; the first and last being those between
which the relations were least numerous and least important. Influenced by
the usual opinions as to the relations between Australia and South America,
the series was at first begun with the Nearctic, and terminated with the
Australian and Neotropical regions; and it was not till the whole of the
vertebrate families had been gone through, and their distribution carefully
studied, that these last two regions were seen to be really wider apart than
any others of the series. It was therefore decided to alter the arrangement,
beginning with the Neotropical, and ending with the Australian regions; and
a careful inspection of the diagrams themselves, taken in their entirety, will,
it is believed, show that this is the most natural plan, and most truly exhibits
the relations of the several regions.

In the portion of our work now commencing, we are not, however, by any
means bound to begin at either end of this series. Each region is studied by
itself, but reference will often have to be made to all the other regions; and
wherever we begin, we must occasionally refer to facts which will be given
further on. As, however, the great northern continents form the central mass
from which the southern regions, as it were, diverge, and as the Palæarctic
region is both more extensive and much better known than any other, it
undoubtedly forms the most convenient starting-point for our proposed
survey of the zoological history of the earth. We thus pass from the better

known to the less known—from Europe to Africa and tropical Asia, and
thence to Australia, completing the series of regions of the Eastern
Hemisphere. Beginning again with the Neotropical region, we pass to the
Nearctic, which has such striking relations with the preceding and with the
Palæarctic region, that it can only be properly understood by constant
reference to both. We thus keep separate the Eastern and Western
hemispheres, which form, from our point of view, the most radical and most
suggestive division of terrestrial faunas; and as we are able to make this
also the dividing point of our two volumes, reference to the work will be
thereby facilitated.

Cosmopolitan Groups.—Before proceeding to sketch the zoological
features of the several Regions it will be well to notice those family groups
which belong to the earth as a whole, and which are so widely and
universally distributed over it that it will be unnecessary, in some cases, to
do more than refer to them under the separate geographical divisions.

The only absolutely cosmopolitan families of Mammalia are those which
are aerial or marine; and this is one of the striking proofs that their
distribution has been effected by natural causes, and that the permanence of
barriers is one of the chief agencies in the limitation of their range. Even
among the aerial bats, however, only one family—the Vespertilionidæ—is
truly cosmopolitan, the others having a more or less restricted range.
Neither are the Cetacea necessarily cosmopolitan, most of the families
being restricted either to warm or to cold seas; but one family, the dolphins
(Delphinidæ), is truly so. This order however will not require further notice,
as, being exclusively marine the groups do not enter into any of our
terrestrial regions. The only other family of mammals that may be
considered to be cosmopolitan, is the Muridæ (rats and mice); yet these are
not entirely so, since none are known to be truly indigenous in any part of
the Australian region except Australia itself.

In the class of Birds, a number of families are cosmopolites, if we reckon as
such all which are found in each region and sub-region; but several of these

are so abundant in some parts, while they are so sparingly represented in
others, that they cannot fairly be considered so. We shall confine that term
therefore, to such as, there is reason to believe, inhabit every important sub-
division of each region. Such are, among the Passerine birds the crows
(Corvidæ), and swallows (Hirundinidæ); among the Picariæ the kingfishers
(Alcedinidæ); among other Land birds the pigeons (Columbidæ), grouse
and partridges (Tetraonidæ), hawks (Falconidæ), and owls (Strigidæ);
among the Waders the rails (Rallidæ), snipes (Scolopacidæ), plovers
(Charadriadæ), and herons (Ardeidæ); and among the Swimmers the ducks
(Anatidæ), gulls (Laridæ), petrels (Procellariidæ), pelicans (Pelecanidæ),
and grebes (Podicipidæ).

In the class of Reptiles there are few absolutely cosmopolitan families,
owing to the scarcity of members of this group in some insular sub-regions,
such as New Zealand and the Pacific Islands. Those which are most nearly
so are the Colubridæ among snakes, and the Scincidæ among lizards.

There is no cosmopolitan family of Amphibia, the true frogs (Ranidæ)
being the most widely distributed.

Neither is any family of Freshwater Fishes cosmopolitan, the Siluridæ,
which have the widest range, being confined to warm regions, and
becoming very scarce in the temperate zones.

Among the Diurnal and Crepuscular Lepidoptera (butterflies and sphinges)
the following families are cosmopolitan:—Satyridæ, Nymphalidæ,
Lycænidæ, Pieridæ, Papilionidæ, Hesperidæ, Zygænidæ, and Sphingidæ.

Of the Coleoptera almost all, except some of the small and obscure
families, are cosmopolitan.

Of the terrestrial Mollusca, the Helicidæ alone are true cosmopolites.

Tables of Distribution of Families and Genera.—Having been obliged to
construct numerous tables of the distribution of the various groups for the
purposes of the descriptive part of the work, I have thought it well to
append the most important of them, in a convenient form, to the chapter on
each region; as much information will thereby be given, which can only be
obtained from existing works at the cost of great labour. All these tables are
drawn up on a uniform plan, the same generic and family names being used
in each; and all are arranged in the same systematic order, so as to be
readily comparable with each other. This, although it seems a simple and
natural thing to do, has involved a very great amount of labour, because
hardly two authors use the same names or follow the same arrangement.
Hence comparison between them is impossible, till all their work has been
picked to pieces, their synonymy unravelled, their differences accounted
for, and the materials recast; and this has to be done, not for two or three
authors only, but for the majority of those whose works have been consulted
on the zoology of any part of the globe.

Except in the two higher orders—Mammalia and Birds—materials do not
exist for complete tables of the genera brought down to the present time.
We have given therefore, first, a complete table of all the families of
Vertebrata and Diurnal Lepidoptera found in each region, showing the sub-
regions in which they occur, and their range beyond the limits of the region.
Families which are wholly peculiar to the region, or very characteristic and
almost exclusively confined to it, are in italics. The number prefixed to each
family corresponds to that of the series of families in the Fourth Part of this
work, so that if further information is required it can be readily referred to
without consulting the index. Names inclosed in parentheses—( . . . ) thus
—indicate families which only just enter a region from an adjacent one, to
which they properly belong. The eye is thus directed to the more, and the
less important families; and a considerable amount of information as to the
general features of the zoology of the region, is conveyed in the easiest
manner.

The tables of genera of Mammalia and Birds, are arranged on a somewhat
different plan. Each genus is given under its Family and Order, and they
follow in the same succession in all the tables. The number of species of
each genus, inhabiting the region, is given as nearly as can be ascertained;

but in many cases this can only be a general approximation. The
distribution of the genera within the region, is then given with some detail;
and, lastly, the range of the genus beyond the region is given in general
terms, the words "Oriental," "Ethiopian," &c., being used for brevity, to
indicate that the genus occurs over a considerable part of such regions.
Genera which are restricted to the region (or which are very characteristic
of it though just transgressing its limits) are given in italics; while those
which only just enter the region from another to which they really belong,
are enclosed in parentheses—( . . . ) thus. The genera are here numbered
consecutively, in order that the number of genera in each family or each
order, in the region, may be readily ascertained (by one process of
subtraction), and thus comparisons made with other regions or with any
other area. As the tables of birds would be swelled to an inconvenient
length by the insertion in each region of all the genera of Waders and
Aquatics, most of which have a very wide range and would have to be
repeated in several or all the regions, these have been omitted; but a list has
been given of such of the genera as are peculiar to, or highly characteristic
of each region.

As this is the first time that any such extensive tables of distribution have
been constructed for the whole of the Mammalia and Birds, they must
necessarily contain many errors of detail; but with all their imperfections it
is believed they will prove very useful to naturalists, to teachers, and to all
who take an intelligent interest in the wider problems of geography and
natural history.

CHAPTER X.

T H E PA L Æ A R C T I C R E G I O N .

This region is of immense extent, comprising all the temperate portions of
the great eastern continents. It thus extends from the Azores and Canary
Islands on the west to Japan on the east, a distance not far short of half the
circumference of the globe. Yet so great is the zoological unity of this vast
tract, that the majority of the genera of animals in countries so far removed
as Great Britain and Northern Japan are identical. Throughout its northern
half the animal productions of the Palæarctic region are very uniform,
except that the vast elevated desert-regions of Central Asia possess some
characteristic forms; but in its southern portion, we find a warm district at
each extremity with somewhat contrasted features. On the west we have the
rich and luxuriant Mediterranean sub-region, possessing many peculiar
forms of life, as well as a few which are more especially characteristic of
the Ethiopian region. On the east we have the fertile plains of Northern
China and the rich and varied islands of Japan, possessing a very distinct set
of peculiar forms, with others belonging to the Oriental region, into which
this part of the Palæarctic region merges gradually as we approach the
Tropic of Cancer. Thus, the countries roughly indicated by the names—
Northern Europe, the Mediterranean district, Central and Northern Asia,
and China with Japan—have each well-marked minor characteristics which
entitle them to the rank of sub-regions. Their boundaries are often
indefinable; and those here adopted have been fixed upon to some extent by
considerations of convenience, dependent on custom and on the more or
less perfect knowledge we possess of some of the intervening countries.

Zoological Characteristics of the Palæarctic Region.—The Palæarctic
region has representatives of thirty-five families of mammalia, fifty-five of
birds, twenty-five of reptiles, nine of amphibia, and thirteen of freshwater
fishes. Comparing it with the only other wholly temperate region, the
Nearctic, we find a much greater variety of types of mammalia and birds.
This may be due in part to its greater area, but more, probably, to its
southern boundary being conterminous for an enormous distance with two
tropical regions, the Ethiopean and Oriental; whereas the Nearctic has a
comparatively short southern boundary conterminous with the Neotropical
region only. This is so very important a difference, that it is rather a matter
of surprise that the two north temperate regions should not be more unequal
in the number of their higher vertebrate forms, than they actually are.

It is also to the interblending of the Palæarctic with the two adjacent
tropical regions, that we must attribute its possession of so few peculiar
family groups. These are only three; two of reptiles, Trogonophidæ and
Ophiomoridæ, and one of fishes, Comephoridæ. The number of peculiar
genera is, however, considerable, as the following enumeration will show.

Mammalia.—The monkey of Gibraltar and North Africa, and an allied
species found in Japan, are now considered to belong to the extensive
eastern genus Macacus. The former, however, is peculiar in the entire

absence of the tail, and has by many naturalists, been held to form a distinct
genus, Inuus, confined to the Palæarctic region.

Of bats there are one or two genera (Barbastellus, Plecotus) which seem to
be mainly or wholly Palæarctic, but the classification of these animals is in
such an unsettled state that the distribution of the genera is of little
importance.

In the next order, Insectivora, we have almost the entire family of the Moles
confined to the region. Talpa just enters Northern India; and Urotrichus is
common to Japan and North-Western America, but the remaining genera,
six in number, are all exclusively Palæarctic.

Among Carnivora we have Nyctereutes, the curious racoon-dog of Japan
and North-Eastern Asia; Lutronectes, an otter peculiar to Japan; and the
badger (Meles), which ranges over the whole region, and just enters the
Oriental region as far as Hongkong; Æluropus, a curious form of the
Himalayan panda, inhabiting the high mountains of Eastern Thibet; and
Pelagius, a genus of seals, ranging from the shores of Madeira to the Black
Sea.

The Ungulata, or hoofed animals, are still more productive of forms
peculiar to this region. First we have the Camels, whose native home is the
desert region of Central and Western Asia and Northern Africa, and which,
even in their domesticated condition, are confined almost wholly within the
limits of the Palæarctic region. Of Deer we have six peculiar genera, Dama
and Capreolus found in Europe, with Elaphodus, Lophotragus, Hydropotes,
and Moschus, confined to Northern China and Mongolia. The great family
Bovidæ—comprising the oxen, sheep, goats and antelopes—furnishes no
less than seven peculiar Palæarctic genera. These are Poephagus, the yak of
Thibet; Addax, a well-known antelope of Northern Africa and Syria;
Procapra, Pantholops and Budorcas, antelopine genera peculiar to Thibet
and Mongolia; with Rupicapra (the chamois), and the extraordinary large-
nosed antelope Saiga, confined to Europe and Western Asia. Besides these
we have Capra (the wild sheep and goats), all the numerous species of
which, except two, are exclusively Palæarctic.

Coming to the Rodents, we have again many peculiar forms. Of Muridæ
(the mouse and rat tribe), we have six peculiar genera, the more important
being Cricetus, Rhombomys Sminthus, and Myospalax. Of Spalacidæ
(mole-rats) both the Palæarctic genera, Ellobius and Spalax, are peculiar.
Ctenodactylus, a genus of the South American family Octodontidæ, is
found only in North Africa. To these we may add Myoxus (the dormice) and
Lagomys (the pikas or tail-less hares) as essentially Palæarctic, since but
one species of each genus is found beyond the limits of the region.

Birds.—It appears to have been the opinion of many naturalists that the
Palæarctic region could not be well characterised by its peculiar genera of
birds. In Mr. Sclater's celebrated paper already referred to, he remarks, "It
cannot be denied that the ornithology of the Palæarctic region is more easily
characterised by what it has not than by what it has," and this has been quite
recently quoted by Mr. Allen, in his essay on the distribution of North
American birds, as if it represented our present knowledge of the subject.
But, thanks to the labours of Dr. Jerdon, Mr. Swinhoe, Père David and
others, we have now learnt that a large number of birds included in the
Indian list, are either mere winter emigrants from Central Asia, or only
inhabit the higher ranges of the Himalayas, and thus really belong to the
Palæarctic region. The result is, that a host of genera are now seen to be
either exclusively or characteristically Palæarctic, and we have no further
difficulty in giving positive ornithological characters to the region. In the
tables appended to this chapter, all these truly Palæarctic genera will be
found printed in italics, with an indication of their distribution, which will
sometimes be found more fully given under the respective families in the
fourth part of this work. Referring to this table for details we shall here
summarise the results.

Of the Sylviidæ or warblers, no less than fourteen genera are either
exclusively or characteristically Palæarctic, of which Locustella, Sylvia,
Curruca and Erithacus are good examples. Of the oriental family
Timaliidæ, the genus Pterorhinus is Palæarctic. Of Panuridæ, or reedlings,
there are four peculiar genera (comprising almost the whole family); of
Certhiidæ, or creepers, one—Tichodroma—which extends southward to the
Abyssinian highlands. Of Paridæ, or tits, one—Acredula; of Corvidæ, or
crows, four—Pica (containing our magpie) being a good example; of

Fringillidæ, or finches and buntings, twelve, among which Acanthis,
Pyrrhula and Emberiza are good illustrations; of Alaudidæ, or larks, there
are two peculiar genera. Leaving the Passeres we next come to peculiar
forms among the gallinaceous birds: Syrrhaptes among the Pteroclidæ or
sand grouse; four genera of Tetraonidæ or grouse and partridges, and five of
Phasianidæ or pheasants, comprising some of the most magnificent birds in
the world. Lastly among the far-wandering aquatic birds we have no less
than five genera which are more especially Palæarctic,—Ortygometra, the
corn-crake, and Otis, the great bustard, being typical examples. We may add
to these, several genera almost confined to this region, such as Garrulus
(jays), Fringilla (true finches), Yunx (wrynecks) and some others; so that in
proportion to its total generic forms a very large number are found to be
peculiar or characteristic.

This view, of the high degree of speciality of the Palæarctic region, will no
doubt be objected to by some naturalists, on the ground that many of the
genera reckoned as exclusively Palæarctic are not so, but extend more or
less into other regions. It is well, therefore, to consider what principles
should guide us in a matter of this kind, especially as we shall have to apply
the same rules to each of the other regions. We may remark first, that the
limits of the regions themselves are, when not formed by the ocean,
somewhat arbitrary, depending on the average distribution of a number of
characteristic forms; and that slight local peculiarities of soil, elevation, or
climate, may cause the species of one region to penetrate more or less
deeply into another. The land boundary between two regions will be, not a
defined line but a neutral territory of greater or less width, within which the
forms of both regions will intermingle; and this neutral territory itself will
merge imperceptibly into both regions. So long therefore as a species or
genus does not permanently reside considerably beyond the possible limits
of this neutral territory, we should not claim it as an inhabitant of the
adjacent region. A consideration of perhaps more importance arises, from
the varying extent of the range of a genus, over the area occupied by the
region. Some genera are represented by single species existing only in a
very limited area; others by numerous species which occupy, entirely or
very nearly, the whole extent of the region; and there is every intermediate
grade between these extremes. Now, the small localised genera, are always
reckoned as among the best examples of types peculiar to a region; while

the more wide-spread groups are often denied that character if they extend a
little beyond the supposed regional limits, or send one or two, out of a large
number of species, into adjacent regions; yet there is some reason to believe
that the latter are really more important as characterising a zoological
region than the former. In the case of a single isolated species or genus we
have a dying-out group; and we have so many cases of discontinuous
species of such groups (of which Urotrichus in Japan and British Columbia,
Eupetes in Sumatra and New Guinea are examples), that it is quite as
probable as not, that any such isolated species has only become peculiar to
the region by the recent extinction of an allied form or forms in some other
region. On the other hand, a genus consisting of numerous species ranging
over an entire region or the greater part of one, is a dominant group, which
has most likely been for some time extending its range, and whose origin
dates back to a remote period. The slight extension of such a group beyond
the limits of the region to which it mainly belongs, is probably a recent
phenomenon, and in that case cannot be held in any degree to detract from
its value as one of the peculiar forms of that region.

The most numerous examples of this class, are those birds of the temperate
regions which in winter migrate, either wholly or partially, into adjacent
warmer countries. This migration most likely began subsequent to the
Miocene period, during that gradual refrigeration of the temperate zones
which culminated in the glacial epoch, and which still continues in a
mitigated form. Most of the genera, and many even of the species of birds
which migrate southwards in winter, have therefore, most likely, always
been inhabitants of our present Palæarctic and Nearctic regions; permanent
residents during warm epochs, but only able now to maintain their existence
by migration in winter. Such groups belong truly to the temperate zones,
and the test of this is the fact of their not having any, or very few,
representatives, which are permanent residents in the adjacent tropical
regions. When there are such representative species, we do not claim them
as peculiar to the Northern regions. Bearing in mind these various
considerations, it will be found that we have been very moderate in our
estimate of the number of genera that may fairly be considered as
exclusively or characteristically Palæarctic.

Reptiles and Amphibia.—The Palæarctic region possesses, in proportion to
its limited reptilian fauna, a full proportion of peculiar types. We have for
instance two genera of snakes, Rhinechis and Halys; seven of lizards,
Trigonophis, Psammodromus, Hyalosaurus, Scincus, Ophiomorus,
Megalochilus, and Phrynocephalus; eight of tailed batrachians, Proteus,
Salamandra, Seiranota, Chioglossa, Hynobius, Onychodactylus, Geotriton,
and Sieboldia; and eight of tail-less batrachians, Bombinator, Pelobates,
Didocus, Alytes, Pelodytes, Discoglossus, Laprissa, and Latonia. The
distribution of these and other Palæarctic genera will be found in our
second vol. chap. xix.

Freshwater Fish.—About twenty genera of freshwater fishes are wholly
confined to this region, and constitute a feature which ought not to be
overlooked in estimating its claim to the rank of a separate primary division
of the earth. They belong to the following families:—Percidæ (three
genera), Acerina, Percarina, Aspro; Comephoridæ (one genus),
Comephorus, found only in Lake Baikal; Salmonidæ (three genera),
Brachymystax, Luciotrutta, and Plecoglossus; Cyprinodontidæ (one genus),
Tellia, found only in Alpine pools on the Atlas Mountains; Cyprinidæ
(thirteen genera), Cyprinus, Carassus, Paraphoxinus, Tinca, Achilognathus,
Rhodeus, Chondrostoma, Pseudoperilampus, Ochetebius, Aspius, Alburnus,
Misgurnus, and Nemachilus.

Summary of Palæarctic Vertebrata.—Summarising these details, we find
that the Palæarctic region possesses thirty-five peculiar genera of
mammalia, fifty-seven of birds, nine of reptiles, sixteen of amphibia, and
twenty-one of freshwater fishes; or a total of 138 peculiar generic types of
vertebrata. Of these, 87 are mammalia and land-birds out of a total of 274
genera of these groups; or rather less than one-third peculiar, a number
which will serve usefully to compare with the results obtained in other
regions.

In our chapter on Zoological Regions we have already pointed out the main
features which distinguish the Palæarctic from the Oriental and Ethiopian
regions. The details now given will strengthen our view of their radical

distinctness, by showing to how considerable an extent the former is
inhabited by peculiar, and often very remarkable generic types.

Insects: Lepidoptera.—The Diurnal Lepidoptera, or butterflies, are not very
abundant in species, their number being probably somewhat over 500, and
these belong to not more than fifty genera. But no less than fifteen of these
genera are wholly confined to the region. Nine of the families are
represented, as follows:—1. Danaidæ; having only a single species in South
Europe. 2. Satyridæ; well represented, there being more than 100 species in
Europe, and three peculiar genera. 3. Nymphalidæ; rather poorly
represented, Europe having only about sixty species, but there is one
peculiar genus. 4. Libytheidæ; a very small family, represented by a single
species occurring in South Europe. 5. Nemeobiidæ; a rather small family,
also having only one species in Europe, but which constitutes a peculiar
genera. 6. Lycænidæ; an extensive family, fairly represented, having about
eighty European species; there are two peculiar genera in the Palæarctic
region. 7. Pieridæ; rather poorly represented with thirty-two European
species; two of the genera are, however, peculiar. 8. Papilionidæ; very
poorly represented in Europe with only twelve species, but there are many
more in Siberia and Japan. No less than five of the small number of genera
in this family are wholly confined to the region, a fact of much importance,
and which to a great extent redeems the character of the Palæarctic region
as regard this order of insects. Their names are Mesapia, Hypermnestra,
Doritis, Sericinus, and Thais; and besides these we have Parnassius—the
"Apollo" butterflies—highly characteristic, and only found elsewhere in the
mountains of the Nearctic region. 9. Hesperidæ; poorly represented with
about thirty European species, and one peculiar genus.

Four families of Sphingina occur in the Palæarctic region, and there are
several peculiar genera.

In the Zygænidæ there are two exclusively European genera, and the
extensive genus Zygæna is itself mainly Palæarctic. The small family
Stygiidæ has two out of its three genera confined to the Palæarctic region.
In the Ægeriidæ the genus Ægeria is mainly Palæarctic. The Sphingidæ

have a wider general range, and none of the larger genera are peculiar to
any one region.

Coleoptera.—The Palæarctic region is the richest portion of the globe in the
great family of Carabidæ, or predacious ground-beetles, about 50 of the
genera being confined to it, while many others, including the magnificent
genus Carabus, have here their highest development. While several of the
smaller genera are confined to the eastern or western sub-regions, most of
the larger ones extend over the whole area, and give it an unmistakable
aspect; while in passing from east to west or vice-versâ, allied species and
genera replace each other with considerable regularity, except in the
extreme south-east, where, in China and Japan, some Oriental forms appear,
as do a few Ethiopian types in the south-west.

Cicindelidæ, or tiger-beetles, are but poorly represented by about 70 species
of the genus Cicindela, and a single Tetracha in South Europe.

Lucanidæ, or stag-beetles, are also poor, there being representatives of 8
genera. One of these, Æsalus (a single species), is peculiar to South Europe,
and two others, Cladognathus and Cyclopthalmus, are only represented in
Japan, China, and Thibet.

Cetoniidæ, or rose-chafers, are represented by 13 genera, two of which are
peculiar to South Europe (Tropinota and Heterocnemis), while
Stalagmosoma, ranging from Persia to Nubia, and the fine Dicranocephalus
inhabiting North China, Corea, and Nipal, may also be considered to belong
to it. The genera Trichius, Gnorimus, and Osmoderma are confined to the
two north temperate regions.

Buprestidæ, or metallic beetles, are rather abundant in the warmer parts of
the region, 27 genera being represented, nine of which are peculiar. By far
the larger portion of these are confined to the Mediterranean sub-region. A
considerable number also inhabit Japan and China.

The Longicorns, or long-horned beetles, are represented by no less than 196
genera, 51 of which are peculiar. They are much more abundant in the

southern than the northern half of the region. Several Oriental genera
extend to Japan and North China, and a few Ethiopian genera to North
Africa. Thirteen genera are confined, to the two north temperate regions.
Several large genera, such as Dorcadion (154 species), Phytæcia (85
species), Pogonochærus (22 species), Agapanthia (22 species), and
Vesperus (7 species), are altogether peculiar to the Palæarctic region; and
with a preponderance of Leptura, Grammoptera, Stenocorus, and several
others, strongly characterise it as distinct from the Nearctic and Oriental
regions.

The other families which are well developed in the Palæarctic regions, are,
the Staphylinidæ or rove-beetles, Silphidæ or burying-beetles, Histeridæ or
mimic-beetles, Nitidulidæ, Aphodiidæ, Copridæ (especially in South
Europe), Geotrupidæ or dung-beetles, Melolonthidæ or chafers, Elateridæ
or click-beetles, the various families of Malacoderms and Heteromera,
especially Pimeliidæ in the Mediterranean sub-region, Curculionidæ or
weevils, the Phytophaga or leaf-eaters, and Cocinellidæ or lady-birds.

The number of species of Coleoptera in the western part of the Palæarctic
region is about 15,000, and there are probably not more than 2,000 to add to
this number from Siberia, Japan, and North China; but were these countries
as well explored as Europe, we may expect that they would add at least
5,000 to the number above given, raising the Palæarctic Coleopterous fauna
to 20,000 species. As the total number of species at present known to exist
in collections is estimated (and perhaps somewhat over-estimated) at 70,000
species, we may be sure that were the whole earth as thoroughly
investigated as Europe, the number would be at least doubled, since we
cannot suppose that Europe, with the Mediterranean basin, can contain
more than one-fifth of the whole of the Coleoptera of the globe.

Of the other orders of insects we here say nothing, because in their case
much more than in that of the Coleoptera and Lepidoptera, is the
disproportion enormous between our knowledge of the European fauna and
that of almost all the rest of the globe. They are, therefore, at present of
comparatively little use for purposes of geographical distribution, even

were it advisable to enter into the subject in a work which will, perhaps, be
too much overburdened with details only of interest to specialists.

Land Shells.—These are very numerous in the warmer parts of the region,
but comparatively scarce towards the North. South Europe alone possesses
over 600 species, whereas there are only 200 in all Northern Europe and
Asia. The total number of species in the whole region is probably about
1,250, of which the great majority are Helicidæ; the Operculated families
being very poorly represented. Several small genera or sub-genera are
peculiar to the region, as Testacella (West Europe and Canaries);
Leucochroa (Mediterranean district); Acicula (Europe); Craspedopoma
(Atlantic Islands); Leonia (Algeria and Spain); Pomatias (Europe and
Canaries); Cecina (Mongolia). The largest genera are Helix and Clausilia,
which together comprise more than half the species; Pupa, very numerous;
Bulimus and Achatina in moderate numbers, and all the rest small. Helix is
the only genus which contains large and handsome species; Bulimus and
Achatina, so magnificent in tropical countries, being here represented by
small and obscure forms only. Daudebardia is confined to Central and
South Europe and New Zealand; Glandina is chiefly South American;
Hyalina is only American and European; Buliminus ranges over all the
world except America; and the other European genera of Helicidæ are
widely distributed. Of the Operculata, Cyclotus, Cyclophorus, and Pupina
extend from the Oriental region into Japan and North China; Tudoria is
found in Algeria and the West Indies; Hydrocena is widely scattered, and
occurs in South Europe and Japan. The genera of freshwater shells are all
widely distributed.

The Palæarctic Sub-regions.

The four sub-regions which are here adopted, have been fixed upon as those
which are, in the present state of our knowledge, at once the most natural
and the only practicable ones. No doubt all of them could be
advantageously again subdivided, in a detailed study of the geographical
distribution of species. But in a general work, which aims at treating all
parts of the world with equal fulness, and which therefore is confined
almost wholly to the distribution of families and genera, such further

subdivision would be out of place. It is even difficult, in some of the classes
of animals, to find peculiar or even characteristic genera for the present sub-
regions; but they all have well marked climatic and physical differences,
and this leads to an assemblage of species and of groups which are
sufficiently distinctive.

I. Central and Northern Europe.

This sub-region, which may perhaps be termed the "European," is
zoologically and botanically the best known on the globe. It can be pretty
accurately defined, as bounded on the south by the Pyrenees, the Alps, the
Balkans, the Black Sea, and the Caucasus range; and by the Ural
Mountains, or perhaps more correctly the valley of the Irtish and Caspian
Sea, on the east; while Ireland and Iceland are its furthest outliers in the
west. To the north, it merges so gradually into the Arctic zone that no
demarcation is possible. The great extent to which this sub-region is
interpenetrated by the sea, and the prevalence of westerly winds bringing
warmth and moisture from an ocean influenced by the gulf-stream, give it a
climate for the most part genial, and free from extremes of heat and cold. It
is thus broadly distinguished from Siberia and Northern Asia generally,
where a more extreme and rigorous climate prevails.

The whole of this sub-region is well watered, being penetrated by rivers in
every direction; and it consists mainly of plains and undulating country of
moderate elevation, the chief mountain ranges being those of Scandinavia
in the north-west, and the extensive alpine system of Central Europe. But
these are both of moderate height, and a very small portion of their surface
is occupied either by permanent snow-fields, or by barren uplands inimical
to vegetable and animal life. It is, in fact, to these, and the numerous lesser
mountains and hills which everywhere diversify the surface of Europe, that
the variety and abundance of its animal life is greatly due. They afford the
perennial supplies to rivers, and furnish in their valleys and ever varying
slopes, stations suited to every form of existence. A considerable area of
Central Europe is occupied by uplands of moderate elevation, a
comparatively small portion being flat and marshy plains.

Most of the northern and much of the central portions of Europe are
covered with vast forests of coniferous trees; and these, occupying as they
do those tracts where the winter is most severe, supply food and shelter to
many animals who could not otherwise maintain their existence. It is
probable that the original condition of the greater part, if not the whole, of
temperate Europe, except the flat marshes of the river valleys and the sandy
downs of the coast, was that of woodland and forest, mostly of deciduous
trees, but with a plentiful admixture of such hardy evergreens as holly, ivy,
privet, and yew. A sufficient proportion of these primeval woods, and of
artificial plantations which have replaced them, fortunately remain, to
preserve for us most of the interesting forms of life, which were developed
before man had so greatly modified the surface of the earth, and so nearly
exterminated many of its original tenants. Almost exactly in proportion to
the amount of woodland that still remains in any part of Europe, do we find
(other things being equal) the abundance and variety of wild animals; a
pretty clear indication that the original condition of the country was
essentially that of a forest, a condition which only now exists in the thinly
inhabited regions of the north.

Although the sub-region we are considering is, for its extent and latitude,
richly peopled with animal life, the number of genera altogether peculiar to
it is not great. There are, however, several which are very characteristic, and
many species, both of the smaller mammalia and of birds, are wholly
restricted to it.

Mammalia.—The genera wholly confined to this sub-region are only two.
Myogale, the desman, is a curious long-snouted Insectivorous animal
somewhat resembling the water-rat in its habits. There are two species, one
found only on the banks of streams in the French Pyrenees, the other on the
great rivers of Southern Russia. The other peculiar genus, Rupicapra (the
chamois of the Alps), is found on all the high mountains of Central Europe.
Almost peculiar are Spalax (the mole-rat) found only in Eastern Europe and
Western Siberia; and Saiga, an extraordinary large-nosed antelope which
has a nearly similar distribution. Highly characteristic forms, which inhabit
nearly every part of the sub-region, are, Talpa (the mole), Erinaceus, (the
hedgehog), Sorex (the shrew), Meles (the badger), Ursus (the bear), Canis
(the wolf and fox), Mustela (the weasel), Lutra (the otter), Arvicola (the

vole), Myoxus (the dormouse), and Lepus (the hare and rabbit); while Bos
(the wild bull) was, until exterminated by man, no doubt equally
characteristic. Other genera inhabiting the sub-region will be found in the
list given at the end of this chapter.

Birds.—It is difficult to name the birds that are most characteristic of this
sub-region, because so many of the most familiar and abundant are
emigrants from the south, and belong to groups that have a different range.
There is perhaps not a single genus wholly confined to it, and very few that
have not equal claims to be placed elsewhere. Among the more
characteristic we may name Turdus (the thrushes), Sylvia (the warblers),
Panurus (the reedling), Parus (the tits), Anthus (the pipits), Motacilla (the
wagtails), which are perhaps more abundant here than in any other part of
the world, Emberiza (the buntings), Plectrophanes (the snow buntings),
Passer (the house sparrows), Loxia (the crossbills), Linota (the linnets),
Pica (the magpies), Tetrao (grouse), Lagopus (ptarmigan) and many others.

I am indebted to Mr. H. E. Dresser, who is personally acquainted with the
ornithology of much of the North of Europe, for some valuable notes on the
northern range of many European birds. Those which are characteristic of
the extreme Arctic zone, extending beyond 70° north latitude, and tolerably
abundant, are two falcons (Falco gyrfalco and F. peregrinus); the rough-
legged buzzard (Archibuteo lagopus); the snowy owl (Nyctea scandiaca);
the raven (Corvus corax); three buntings (Emberiza schæniculus,
Plectrophanes nivalis and P. calcarata); a lark (Otocorys alpestris); several
pipits, the most northern being Anthus cervinus; a wagtail (Budytes
cinereocapilla); a dipper (Cinclus melanogaster); a warbler (Cyanecula
suecica); the wheatear (Saxicola œnanthe); and two ptarmigans (Lagopus
albus and L. salicetus). Most of these birds are, of course, only summer
visitors to the Arctic regions, the only species noted as a permanent resident
in East Finmark (north of latitude 70°) being the snow-bunting
(Plectrophanes nivalis).

The birds that are characteristic of the zone of pine forests, or from about
61° to 70° north latitude, are very numerous, and it will be sufficient to note
the genera and the number of species (where more than one) to give an idea

of the ornithology of this part of Europe. The birds of prey are, Falco (three
species), Astur (two species), Buteo, Pandion, Surnia, Bubo, Syrnium, Asio,
Nyctala. The chief Passerine birds are, Corvus (two species), Pica,
Garrulus (two species), Nucifraga, Bombycilla, Hirundo (two species),
Muscicapa (two species), Lanius, Sturnus, Passer (two species), Pyrrhula,
Carpodacus, Loxia (two species), Pinicola, Fringilla (eight species),
Emberiza (five species), Alauda, Anthus, Turdus (five species), Ruticilla,
Pratincola, Accentor, Sylvia (four species), Hypolais, Regulus,
Phylloscopus (two species), Acrocephalus, Troglodytes, and Parus (six
species). Woodpeckers are abundant, Picus (four species), Gecinus, and
Yunx. The kingfisher (Alcedo), goatsucker (Caprimulgus), and swift
(Cypselus) are also common. The wood-pigeon (Columba) is plentiful. The
gallinaceous birds are three grouse, Tetrao (two species) and Bonasa, and
the common quail (Coturnix).

The remaining genera and species of temperate or north-European birds, do
not usually range beyond the region of deciduous trees, roughly indicated
by the parallel of 60° north latitude.

Plate I.

THE ALPS OF CENTRAL EUROPE, WITH CHARACTERISTIC ANIMALS.

Plate I.—Illustrating the Zoology of Central Europe.—Before considering
the distribution of the other classes of vertebrata, it will be convenient to
introduce our first illustration, which represents a scene in the Alps of
Central Europe, with figures of some of the most characteristic Mammalia
and Birds of this sub-region. On the left is the badger (Meles Taxus) one of
the weasel family, and belonging to a genus which is strictly Palæarctic. It
abounds in Central and Northern Europe and also extends into North Asia,
but is represented by another species in Thibet and by a third in Japan. The
elegantly-formed creatures on the right are chamois (Rupicapra tragus),
almost the only European antelopes, and wholly confined to the higher
mountains, from the Pyrenees to the Carpathians and the Caucasus. The
chamois is the only species of the genus, and is thus perhaps the most
characteristic European mammal. The bird on the left, above the badgers, is
the Alpine chough, (Fregilus pyrrhocorax). It is found in the high
mountains from the Alps to the Himalayas, and is allied to the Cornish
chough, which is still found on our south-western coasts, and which ranges
to Abyssinia and North China. The Alpine chough differs in having a
shorter bill of an orange colour, and vermilion red feet as in the other
species. In the foreground are a pair of ruffs (Machetes pugnax) belonging
to the Scolopacidæ or snipe family, and most nearly allied to the genus
Tringa or sandpiper. This bird is remarkable for the fine collar of plumes
which adorns the males in the breeding season, when they are excessively
pugnacious. It is the only species of its genus, and ranges over all Europe
and much of Northern Asia, migrating in the winter to the plains of India,
and even down the east coast of Africa as far as the Cape of Good Hope;
but it only breeds in the Palæarctic region, over the greater part of which it
ranges.

Reptiles and Amphibia.—There are no genera of reptiles peculiar to this
sub-region. Both snakes and lizards are comparatively scarce, there being
about fourteen species of the former and twelve of the latter. Our common
snake (Tropidonotus natrix) extends into Sweden and North Russia, but the
viper (Viperus berus) goes further north, as far as Archangel (64° N.), and
in Scandinavia (67° N.), and is the most Arctic of all known snakes. Of the
lizards, Lacerta stirpium (the sand lizard) has the most northerly range,

extending into Poland and Northern Russia; and Anguis fragilis (the blind
or slow-worm) has almost an equal range.

Amphibia, being more adapted to a northern climate, have acquired a more
special development, and thus several forms are peculiar to the North
European sub-region. Most remarkable is Proteus, a singular eel-like
aquatic creature with small legs, found only in the subterranean lakes in
Carniola and Carinthia; Alytes, a curious toad, the male of which carries
about the eggs till they are hatched, found only in Central Europe from
France to the east of Hungary; and Pelodytes, a frog found only in France.
Frogs and toads are very abundant all over Europe, the common frog (Rana
temporaria) extending to the extreme north. The newts (Triton) are also
very abundant and widely spread, though not ranging so far north as the
frogs. The genera Bombinator (a toad-like frog), and Hyla (the tree frog) are
also common in Central Europe.

Freshwater Fish.—Two genera of the perch family (Percidæ) are peculiar to
this sub-region,—Percarina, a fish found only in the river Dniester, and
Aspro, confined to the rivers of Central Europe. Of the very characteristic
forms are, Gasterosteus (stickle-back), which alone forms a peculiar family
—Gasterosteidæ; Perca, Acerina and Lucioperca, genera of the perch
family; Silurus, a large fish found in the rivers of Cenrtal Europe, of the
family Siluridæ; Esox (the pike), of the family Esocidæ; Cyprinus (carp),
Gobio (gudgeon), Leuciscus (roach, chub, dace, &c.), Tinca (tench),
Abramus (bream), Alburnus (bleak), Cobitis (loach), all genera of the
family Cyprinidæ.

Insects—Lepidoptera.—No genera of butterflies are actually confined to
this sub-region, but many are characteristic of it. Parnassius, Aporia,
Leucophasia, Colias, Melitæa, Argynnis, Vanessa, Limenitis, and
Chionobas, are all very abundant and widespread, and give a feature to the
entomology of most of the countries included in it.

Coleoptera.—This sub-region is very rich in Carabidæ; the genera
Elaphrus, Nebria, Carabus, Cychrus, Pterostichus, Amara, Trechus and
Peryphus being especially characteristic. Staphylinidæ abound. Among

Lamellicorns the genus Aphodius is most characteristic. Buprestidæ are
scarce; Elateridæ more abundant. Among Malacoderms Telephorus and
Malachius are characteristic. Curculionidæ abound: Otiorhyuchus, Omias,
Erirhinus, Bagous, Rhynchites and Ceutorhynchus being very characteristic
genera. Of Longicorns Callidium, Dorcadion, Pogonochærus, Pachyta and
Leptura are perhaps the best representatives. Donacia, Crioceris,
Chrysomela, and Altica, are typical Phytophaga; while Coccinella is the
best representative of the Securipalpes.

North European Islands.—The British Islands are known to have been
recently connected with the Continent, and their animal productions are so
uniformly identical with continental species as to require no special note.
The only general fact of importance is, that the number of species in all
groups is much less than in continental districts of equal extent, and that
this number is still farther diminished in Ireland. This may be accounted for
by the smaller area and less varied surface of the latter island; and it may
also be partly due to the great extent of low land, so that a very small
depression would reduce it to the condition of a cluster of small islands
capable of supporting a very limited amount of animal life. Yet further, if
after such a submergence had destroyed much of the higher forms of life in
Great Britain and Ireland, both were elevated so as to again form part of the
Continent, a migration would commence by which they would be stocked
afresh; but this migration would be a work of time, and it is to be expected
that many species would never reach Ireland or would find its excessively
moist climate unsuited to them.

Some few British species differ slightly from their continental allies, and
are considered by many naturalists to be distinct. This is the case with the
red grouse (Lagopus scoticus) among birds; and a few of the smaller
Passeres have also been found to vary somewhat from the allied forms on
the Continent, showing that the comparatively short interval since the
glacial period, and the slightly different physical conditions dependent on
insularity, have sufficed to commence the work of specific modification.
There are also a few small land-shells and several insects not yet found
elsewhere than in Britain; and even one of the smaller Mammalia—a shrew
(Sorex rusticus). These facts are all readily explained by the former union of
these islands with the Continent, and the alternate depressions and

elevations which are proved by geological evidence to have occurred, by
which they have been more than once separated and united again in recent
times. For the evidence of this elevation and depression, the reader may
consult Sir Charles Lyell's Antiquity of Man.

Iceland is the only other island of importance belonging to this sub-region,
and it contrasts strongly with Great Britain, both in its Arctic climate and
oceanic position. It is situated just south of the Arctic circle and
considerably nearer Greenland than Europe, yet its productions are almost
wholly European. The only indigenous land mammalia are the Arctic fox
(Canis lagopus), and the polar bear as an occasional visitant, with a mouse
(Mus islandicus), said to be of a peculiar species. Four species of seals visit
its shores. The birds are more interesting. According to Professor Newton,
ninety-five species have been observed; but many of these are mere
stragglers. There are twenty-three land, and seventy-two aquatic birds and
waders. Four or five are peculiar species, though very closely related to
others inhabiting Scandinavia or Greenland. Only two or three species are
more nearly related to Greenland birds than to those of Northern Europe, so
that the Palæarctic character of the fauna is unmistakable. The following
lists, compiled from a paper by Professor Newton, may be interesting as
showing more exactly the character of Icelandic ornithology.

1. Peculiar species.—Troglodytes borealis (closely allied to the common
wren, found also in the Faroe Islands); Falco islandicus (closely allied to F.
gyrfalco); Lagopus islandorum (closely allied to L. rupestris of Greenland).

2. European species resident in Iceland.—Emberiza nivalis, Corvus corax,
Haliæetus albicilla, Rallus aquaticus, Hæmatopus ostralegus, Cygnus ferus,
Mergus (two species), Phalacocorax (two species), Sula bassana, Larus
(two species), Stercorarius catarractes, Puffinus anglorum, Mergulus alle,
Uria (three species), Alca torda.

3. American species resident in Iceland.—Clangula islandica, Histrionicus
torquatus.

4. Annual visitants from Europe.—Turdus iliacus, Ruticilla tithys, Saxicola
ænanthe, Motacilla alba, Anthus pratensis, Linota linaria, Chelidon urbica,
Hirundo rustica, Falco æsalon, Surnia nyctea, Otus brachyotus,
Charadrius pluvialis, Ægialites hiaticula, Strepsilas interpres, Phalaropus
fulicarius, Totanus calidris, Limosa (species), Tringa (three species),
Calidris arenaria, Gallinago media, Numenius phæopus, Ardea cinerea,
Anser (two species), Bernicla (two species), Anas (four species), Fuligula
marila, Harelda glacialis, Somateria mollissima, Œdemia nigra, Sterna
macrura, Rissa tridactyla, Larus luecopterus, Stercorarius (two species),
Fratercula artica, Colymbus (two species), Podiceps cornutus.

5. Annual visitant from Greenland.—Falco candicans.

6.—Former resident, now extinct.—Alca impennis (the great auk).

II.—Mediterranean Sub-region.

This is by far the richest portion of the Palæarctic region, for although of
moderate extent much of it enjoys a climate in which the rigours of winter
are almost unknown. It includes all the countries south of the Pyrenees,
Alps, Balkans, and Caucasus mountains; all the southern shores of the
Mediterranean to the Atlas range, and even beyond it to include the extra-
tropical portion of the Sahara; and in the Nile valley as far as the second
cataract. Further east it includes the northern half of Arabia and the whole
of Persia, as well as Beluchistan, and perhaps Affghanistan up to the banks
of the Indus. This extensive district is almost wholly a region of mountains
and elevated plateaus. On the west, Spain is mainly a table-land of more
than 2000 feet elevation, deeply penetrated by extensive valleys and rising
into lofty mountain chains. Italy, Corsica, Sardinia, and Sicily, are all very
mountainous, and much of their surface considerably elevated. Further east
we have all European Turkey and Greece, a mountain region with a
comparatively small extent of level plain. In Asia the whole country, from
Smyrna through Armenia and Persia to the further borders of Affghanistan,
is a vast mountainous plateau, almost all above 2000, and extensive districts
above 5000 feet in elevation. The only large tract of low-land is the valley
of the Euphrates. There is also some low-land south of the Caucasus, and in

Syria the valley of the Jordan. In North Africa the valley of the Nile and the
coast plains of Tripoli and Algiers are almost the only exceptions to the
more or less mountainous and plateau-like character of the country. Much
of this extensive area is now bare and arid, and often even of a desert
character; a fact no doubt due, in great part, to the destruction of aboriginal
forests. This loss is rendered permanent by the absence of irrigation, and, it
is also thought, by the abundance of camels and goats, animals which are
exceedingly injurious to woody vegetation, and are able to keep down the
natural growth of forests. Mr. Marsh (whose valuable work Man and Nature
gives much information on this subject) believes that even large portions of
the African and Asiatic deserts would become covered with woods, and the
climate thereby greatly improved, were they protected from these
destructive domestic animals, which are probably not indigenous to the
country. Spain, in proportion to its extent, is very barren; Italy and
European Turkey are more woody and luxuriant; but it is perhaps in Asia
Minor, on the range of the Taurus, along the shores of the Black Sea, and to
the south of the Caucasus range, that this sub-region attains its maximum of
luxuriance in vegetation and in animal life. From the Caspian eastward
extends a region of arid plains and barren deserts, diversified by a few more
fertile valleys, in which the characteristic flora and fauna of this portion of
the Palæarctic region abounds. Further east we come to the forests of the
Hindoo Koosh, which probably form the limit of the sub-region. Beyond
these we enter on the Siberian sub-region to the north, and on the outlying
portion of the Oriental region on the south.

In addition to the territories now indicated as forming part of the
Mediterranean sub-region, we must add the group of Canary Islands off the
west coast of Africa which seem to be an extension of the Atlas mountains,
and the oceanic groups of Madeira and the Azores; the latter about 1,000
miles from the continent of Europe, yet still unmistakably allied to it both in
their vegetable and animal productions. The peculiarities of the faunas of
these islands will be subsequently referred to.

It seems at first sight very extraordinary, that so large and wide a sea as the
Mediterranean should not separate distinct faunas, and this is the more
remarkable when we find how very deep the Mediterranean is, and
therefore how ancient we may well suppose it to be. Its eastern portion

reaches a depth of 2,100 fathoms or 12,600 feet, while its western basin is
about 1,600 fathoms or 9,600 feet in greatest depth, and a considerable area
of both basins is more than 1,000 fathoms deep. But a further examination
shows, that a comparatively shallow sea or submerged bank incloses Malta
and Sicily, and that on the opposite coast a similar bank stretches out from
the coast of Tripoli leaving a narrow channel the greatest depth of which is
240 fathoms. Here therefore is a broad plateau, which an elevation of about
1,500 feet would convert into a wide extent of land connecting Italy with
Africa; while the same elevation would also connect Morocco with Spain,
leaving two extensive lakes to represent what is now the Mediterranean
Sea, and affording free communication for land animals between Europe
and North Africa. That such a state of things existed at a comparatively
recent period, is almost certain; not only because a considerable number of
identical species of mammalia inhabit the opposite shores of the
Mediterranean, but also because numerous remains of three species of
elephants have been found in caves in Malta,—now a small rocky island in
which it would be impossible for such animals to live even if they could
reach it. Remains of hippopotami are also found at Gibraltar, and many
other animals of African types in Greece; all indicating means of
communication between South Europe and North Africa which no longer
exist. (See Chapter VI. pp. 113-115.)

Mammalia.—There are a few groups of Palæarctic Mammalia that are
peculiar to this sub-region. Such are, Dama, the fallow deer, which is now
found only in South Europe and North Africa; Psammomys, a peculiar
genus of Muridæ, found only in Egypt and Palestine; while Ctenodactylus,
a rat-like animal classed in the South American family Octodontidæ,
inhabits Tripoli. Among characteristic genera not found in other sub-
regions, are, Dysopes, a bat of the family Noctilionidæ; Macroscelides, the
elephant shrew, in North Africa; Genetta, the civet, in South Europe;
Herpestes, the ichneumon, in North Africa and (?) Spain; Hyæna, in South
Europe; Gazella, Oryx, Alcephalus, and Addax, genera of antelopes in
North Africa and Palestine; Hyrax, in Syria; and Hystrix, the porcupine, in
South Europe. Besides these, the camel and the horse were perhaps once
indigenous in the eastern parts of the sub-region; and a wild sheep (Ovis
musmon) still inhabits Sardinia, Corsica, and the mountains of the south-
east of Spain. The presence of the large feline animals—such as the lion,

the leopard, the serval, and the hunting leopard—in North Africa, together
with several other quadrupeds not found in Europe, have been thought by
some naturalists to prove, that this district should not form part of the
Palæarctic region. No doubt several Ethiopian groups and species have
entered it from the south; but the bulk of its Mammalia still remains
Palæarctic, although several of the species have Asiatic rather than
European affinities. The Macacus innuus is allied to an Asiatic rather than
an African group of monkeys, and thus denotes an Oriental affinity.
Ethiopian affinity is apparently shown by the three genera of antelopes, by
Herpestes, and by Macroscelides; but our examination of the Miocene
fauna has shown that these were probably derived from Europe originally,
and do not form any part of the truly indigenous or ancient Ethiopian fauna.
Against these, however, we have the occurrence in North Africa of such
purely Palæarctic and non-Ethiopian genera as Ursus, Meles, Putorius, Sus,
Cervus, Dama, Capra, Alactaga; together with actual European or West
Asiatic species of Canis, Genetta, Felis, Putorius, Lutra, many bats, Sorex,
Crocidura, Crossopus, Hystrix, Dipus, Lepus, and Mus. It is admitted that,
as regards every other group of animals, North Africa is Palæarctic, and the
above enumeration shows that even in Mammalia, the intermixture of what
are now true Ethiopian types is altogether insignificant. It must be
remembered, also, that the lion inhabited Greece even in historic times,
while large carnivora were contemporary with man all over Central Europe.

Birds.—So many of the European birds migrate over large portions of the
region, and so many others have a wide permanent range, that we cannot
expect to find more than a few genera, consisting of one or two species,
each, confined to a sub-region; and such appear to be, Lusciniola and
Pyrophthalma, genera of Sylviidæ. But many are characteristic of this, as
compared with other Palæarctic sub-regions; such as, Bradyptetus, Aedon,
Dromolœa, and Cercomela, among Sylviidæ; Crateropus and
Malacocercus, among Timaliidæ; Telophonus among Laniidæ; Certhilauda
and Mirafra among larks; Pastor among starlings; Upupa, the hoopoe;
Halycon and Ceryle among kingfishers; Turnix and Caccabis among
Gallinæ, and the pheasant as an indigenous bird; together with Gyps, Vultur
and Neophron, genera of vultures. In addition to these, almost all our
summer migrants spend their winter in some part of this favoured land,
mostly in North Africa, together with many species of Central Europe that

rarely or never visit us. It follows, that a large proportion of all the birds of
Europe and Western Asia are to be found in this sub-region, as will be seen
by referring to the list of the genera of the region. Palestine is one of the
remote portions of this region which has been well explored by Canon
Tristram, and it may be interesting to give his summary of the range of the
birds. We must bear in mind that the great depression of the Dead Sea has a
tropical climate, which accounts for the presence here only, of such a
tropical form as the sun-bird (Nectarinea osea).

The total number of the birds of Palestine is 322, and of these no less than
260 are European, at once settling the question of the general affinities of
the fauna. Of the remainder eleven belong to North and East Asia, four to
the Red Sea, and thirty-one to East Africa, while twenty-seven are peculiar
to Palestine. It is evident therefore that an unusual number of East African
birds have extended their range to this congenial district, but most of these
are desert species and hardly true Ethiopians, and do not much interfere
with the general Palæarctic character of the whole assemblage. As an
illustration of how wide-spread are many of the Palæarctic forms, we may
add, that seventy-nine species of land birds and fifty-five of water birds, are
common to Palestine and Britain. The Oriental and Ethiopian genera
Pycnonotus and Nectarinea are found here, while Bessornis and Dromolæa
are characteristically Ethiopian. Almost all the other genera are Palæarctic.

Persia is another remote region generally associated with the idea of
Oriental and almost tropical forms, but which yet undoubtedly belongs to
the Palæarctic region. Mr. Blanford's recent collections in this country, with
other interesting information, is summarised in Mr. Elwes's paper on the
"Geographical Distribution of Asiatic Birds" (Proc. Zool. Soc. 1873, p.
647). No less than 127 species are found also in Europe, and thirty-seven
others belong to European genera; seven are allied to birds of Central Asia
or Siberia, and fifteen to those of North-East Africa, while only three are
purely of Indian affinities. This shows a preponderance of nearly nine-
tenths of Palæarctic forms, which is fully as much as can be expected in any
country near the limits of a great region.

Reptiles and Amphibia.—The climatal conditions being here more
favourable to these groups, and the genera being often of limited range, we
find some peculiar, and several very interesting forms. Rhinechis, a genus
of Colubrine snakes, is found only in South Europe; Trogonophis, one of
the Amphisbænians—curious snake-like lizards—is known only from North
Africa; Psammosaurus, belonging to the water lizards (Varanidæ) is found
in North Africa and North-West India; Psammodromus, a genus of
Lacertidæ, is peculiar to South Europe; Hyalosaurus, belonging to the
family Zonuridæ, is a lizard of especial interest, as it inhabits North Africa
while its nearest ally is the Ophisaurus or "glass snake" of North America;
the family of the scinks is represented by Scincus found in North Africa and
Arabia. Besides these Seps, a genus of sand lizards (Sepidæ) and Agama, a
genus of Agamidæ, are abundant and characteristic.

Of Amphibia we have Seiranota, a genus of salamanders found only in Italy
and Dalmatia; Chioglossa, in Portugal, and Geotriton, in Italy, belonging to
the same family, are equally peculiar to the sub-region.

Freshwater Fish.—One of the most interesting is Tellia, a genus of
Cyprinodontidæ found only in alpine pools in the Atlas mountains.
Paraphoxinius, found in South-East Europe, and Chondrostoma, in Europe
and Western Asia, genera of Cyprimidæ, seem almost peculiar to this sub-
region.

Insects—Lepidoptera.—Two genera of butterflies, Thais and Doritis, are
wholly confined to this sub-region, the former ranging over all Southern
Europe, the latter confined to Eastern Europe and Asia Minor. Anthocharis
and Zegris are very characteristic of it, the latter only extending into South
Russia, while Danais, Charaxes, and Libythea are tropical genera unknown
in other parts of Europe.

Coleoptera.—This sub-region is very rich in many groups of Coleoptera, of
which a few only can be noticed here. Among Carabidæ it possesses
Procerus and Procrustes, almost exclusively, while Brachinus, Cymindis,
Lebia, Graphipterus, Scarites, Chlænius, Calathus, and many others, are
abundant and characteristic. Among Lamellicorns—Copridæ, Glaphyridæ,

Melolonthidæ, and Cetoniidæ abound. Buprestidæ are plentiful, the genera
Julodis, Acmæodera, Buprestis, and Sphenoptera being characteristic.
Among Malacoderms—Cebrionidæ, Lampyridæ, and Malachiidæ abound.
The Tenebrioid Heteromera are very varied and abundant, and give a
character to the sub-region. The Mylabridæ, Cantharidæ, and Œdemeridæ
are also characteristic. Of the immense number of Curculionidæ—
Thylacites, Brachycerus, Lixus, and Acalles may be mentioned as among
the most prominent. Of Longicorns there are few genera especially
characteristic, but perhaps Prinobius, Purpuricenus, Hesperophanes, and
Parmena are most so. Of the remaining families, we may mention
Clythridæ, Hispidæ, and Cassididæ as being abundant.

The Mediterranean and Atlantic Islands.—The various islands of the
Mediterranean are interesting to the student of geographical distribution as
affording a few examples of local species of very restricted range, but as a
rule they present us with exactly the same forms as those of the adjacent
mainland.[6] Their peculiarities do not, therefore, properly come within the
scope of this work. The islands of the Atlantic Ocean belonging to this sub-
region are, from their isolated position and the various problems they
suggest, of much more interest, and their natural history has been carefully
studied. We shall therefore give a short account of their peculiar features.

Of the three groups of Atlantic islands belonging to this sub-region, the
Canaries are nearest to the Continent, some of the islands being only about
fifty miles from the coast of Africa. They are, however, separated from the
mainland by a very deep channel (more than 5,000 feet), as shown on our
general map. The islands extend over a length of 300 miles; they are very
mountainous and wholly volcanic, and the celebrated peak of Teneriffe rises
to a height of more than 12,000 feet. The small Madeira group is about 400
miles from the coast of Morocco and 600 from the southern extremity of
Portugal; and there is a depth of more than 12,000 feet between it and the
continent. The Azores are nearly 1,000 miles west of Lisbon. They are quite
alone in mid-Atlantic, the most westerly islands being nearer
Newfoundland than Europe, and are surrounded by ocean depths of from
12,000 to 18,000 feet. It will be convenient to take these islands first in
order.

Azores.—Considering the remoteness of this group from every other land, it
is surprising to find as many as fifty-three species of birds inhabiting or
visiting the Azores; and still more to find that they are of Palæarctic genera
and, with one exception, all of species found either in Europe, North Africa,
Madeira, or the Canaries. The exception is a bullfinch peculiar to the
islands, but closely allied to a European species. Of land birds there are
twenty-two, belonging to twenty-one genera, all European. These genera
are Cerchneis, Buteo, Asio, Strix, Turdus, Oriolus, Erithacus, Sylvia,
Regulus, Saxicola, Motacilla, Plectrophanes, Fringilla, Pyrrhula, Serinus,
Sturnus, Picus, Upupa, Columba, Caccabis, and Coturnix. Besides the
bullfinch (Pyrrhula) other species show slight differences from their
European allies, but not such as to render them more than varieties. The
only truly indigenous mammal is a bat of a European species. Nine
butterflies inhabit the Azores; eight of them are European species, one
North American. Of beetles 212 have been collected, of which no less than
175 are European species; of the remainder, nineteen are found in the
Canaries or Madeira, three in South America, while fourteen are peculiar to
the islands.

Now these facts (for which we are indebted to Mr. Godman's Natural
History of the Azores) are both unexpected and exceedingly instructive. In
most other cases of remote Oceanic islands, a much larger proportion of the
fauna is endemic, or consists of peculiar species and often of peculiar
genera; as is well shown by the case of the Galapagos and Juan Fernandez,
both much nearer to a continent and both containing peculiar genera and
species of birds. Now we know that the cause and meaning of this
difference is, that in the one case the original immigration is very remote
and has never or very rarely been repeated, so that under the unchecked
influence of new conditions of life the species have become modified; in
the other case, either the original immigration has been recent, or if remote
has been so frequently repeated that the new comers have kept up the purity
of the stock, and have not allowed time for the new conditions to produce
the effect we are sure they would in time produce if not counteracted. For
Mr. Godman tells us that many of the birds are modified—instancing the
gold-crested wren, blackcap, and rock dove—and he adds, that the
modification all tends in one direction—to produce a more sombre
plumage, a greater strength of feet and legs, and a more robust bill. We

further find, that four of the land-birds, including the oriole, snow-bunting,
and hoopoe, are not resident birds, but straggle accidentally to the islands
by stress of weather; and we are told that every year some fresh birds are
seen after violent storms. Add to this the fact, that the number of species
diminishes in the group as we go from east to west, and that the islands are
subject to fierce and frequent storms blowing from every point of the
compass,—and we have all the facts requisite to enable us to understand
how this remote archipelago has become stocked with animal life without
ever probably being much nearer to Europe than it is now. For the islands
are all volcanic, the only stratified rock that occurs being believed to be of
Miocene date.

Madeira and the Canaries.—Coming next to Madeira, we find the number
of genera of land birds has increased to twenty-eight, of which seventeen
are identical with those of the Azores. Some of the commonest European
birds—swallows, larks, sparrows, linnets, goldfinches, ravens, and
partridges, are among the additions. A gold-crested warbler, Regulus
Maderensis, and a pigeon, Columba Trocaz, are peculiar to Madeira.

In the Canaries we find that the birds have again very much increased, there
being more than fifty genera of land birds; but the additions are wholly
European in character, and almost all common European species. We find a
few more peculiar species (five), while some others, including the wild
canary, are common to all the Atlantic Islands or to the Canaries and
Madeira. Here, too, the only indigenous mammalia are two European
species of bats.

Land Shells.—The land shells of Madeira offer us an instructive contrast to
the birds of the Atlantic Islands. About fifty-six species have been found in
Madeira, and forty-two in the small adjacent island of Porto Santo, but only
twelve are common to both, and all or almost all are distinct from their
nearest allies in Europe and North Africa. Great numbers of fossil shells are
also found in deposits of the Newer Pliocene period; and although these
comprise many fresh species, the two faunas and that of the continent still
remain almost as distinct from each other as before. It has been already
stated (p. 31) that the means by which land mollusca have been carried

across arms of the sea are unknown, although several modes may be
suggested; but it is evidently a rare event, requiring some concurrence of
favourable conditions not always present. The diversity and specialization
of the forms of these animals is, therefore, easily explained by the fact, that,
once introduced they have been left to multiply under the influence of a
variety of local conditions, which inevitably lead, in the course of ages, to
the formation of new varieties and new species.

Coleoptera.—The beetles of Madeira and the Canaries have been so
carefully collected and examined by Mr. T. V. Wollaston, and those of the
Azores described and compared by Mr. Crotch, and they illustrate so many
curious points in geographical distribution, that it is necessary to give some
account of them. No less than 1,480 species of beetles have been obtained
from the Canaries and Madeira, only 360 of which are European, the
remainder being peculiar to the islands. The Canaries are inhabited by a
little over 1,000 species, Madeira by about 700, while 240 are common to
both; but it is believed that many of these have been introduced by man. In
the Azores, 212 species have been obtained, of which 175 are European;
showing, as in the birds, as closer resemblance to the European fauna than
in the other islands which, although nearer to the continent, offer more
shelter and are situated in a less tempestuous zone. Of the non-European
species in the Azores, 19 are found also in the other groups of islands, 14
are peculiar, while 3 are American. Of the European species, 132 are found
also in the other Atlantic islands, while 43 have reached the Azores only.
This is interesting as showing to how great an extent the same insects reach
all the islands, notwithstanding the difference of latitude and position; and it
becomes of great theoretical importance, when we find how many extensive
families and genera are altogether absent.

The Madeira group has been more thoroughly explored than any other, and
its comparatively remote situation, combined with its luxuriant vegetation,
have been favourable to the development and increase of the peculiar forms
which characterize all the Atlantic islands in a more or less marked degree.
A consideration of some of its peculiarities will, therefore, best serve to
show the bearing of the facts presented by the insect fauna of the Atlantic
islands, on the general laws of distribution. The 711 species of beetles now
known from the Madeira group, belong to 236 genera; and no less than 44

of these genera are not European but are peculiar to the Atlantic islands.
Most of them are, however, closely allied to European genera, of which
they are evidently modifications. A most curious general feature presented
by the Madeiran beetles, is the total absence of many whole families and
large genera abundant in South Europe. Such are the Cicindelidæ, or tiger
beetles; the Melolonthidæ, or chafers; the Cetoniidæ, or rose-chafers; the
Eumolpidæ and Galerucidæ, large families of Phytophagous, or leaf-eating
beetles; and also the extensive groups of Elateridæ and Buprestidæ, which
are each represented by but one minute species. Of extensive genera
abundant in South Europe, but wholly absent in Madeira, are Carabus,
Rhizotrogus, Lampyris, and other genera of Malacoderms; Otiorhynchus,
Brachycerus, and 20 other genera of Curculionidæ, comprising more than
300 South European and North African species; Pimelia, Tentyra, Blaps,
and 18 other genera of Heteromera, comprising about 550 species in South
Europe and North Africa; and Timarcha, containing 44 South European and
North African species.

Another most remarkable feature of the Madeiran Coleoptera is the unusual
prevalence of apterous or wingless insects. This is especially the case with
groups which are confined to the Atlantic islands, many of which consist
wholly of wingless species; but it also affects the others, no less than
twenty-two genera which are usually or sometimes winged in Europe,
having only wingless species in Madeira; and even the same species which
is winged in Europe becomes, in at least three cases, wingless in Madeira,
without any other perceptible change having taken place. But there is
another most curious fact noticed by Mr. Wollaston; that those species
which possess wings in Madeira, often have them rather larger than their
allies in Europe. These two facts were connected by Mr. Darwin, who
suggested that flying insects are much more exposed to be blown out to sea
and lost, than those which do not fly (and Mr. Wollaston had himself
supposed that the "stormy atmosphere" of Madeira had something to do
with the matter); so that the most frequent fliers would be continually
weeded out, while the more sluggish individuals, who either could not or
would not fly, remained to continue the race; and this process going on
from generation to generation, would, on the well-ascertained principles of
selection and abortion by disuse, in time lead to the entire loss of wings by
those insects to whom wings were not a necessity. But those whose wings

were essential to their existence would be acted upon in another way. All
these must fly to obtain their food or provide for their offspring, and those
that flew best would be best able to battle with the storms, and keep
themselves safe, and thus those with the longest and most powerful wings
would be preserved. If however all the individuals of the species were too
weak on the wing to resist the storms, they would soon become extinct.[7]

Now this explanation of the facts is not only simple and probable in itself,
but it also serves to explain in a remarkable manner some of the
peculiarities and deficiencies of the Madeiran insect fauna, in harmony with
the view (supported by the distribution of the birds and land shells, and in
particular by the immigrant birds and insects of the Azores) that all the
insects have been derived from the continent or from other islands, by
immigration across the ocean, in various ways and during a long period.
These deficiencies are, on the other hand, quite inconsistent with the theory
(still held by some entomologists) that a land communication is absolutely
necessary to account for the origin of the Madeiran fauna.

First, then, we can understand how the tiger-beetles (Cicindelidæ) are
absent; since they are insects which have a short weak flight, but yet to
whom flight is necessary. If a few had been blown over to Madeira, they
would soon have become exterminated. The same thing applies to the
Melolonthidæ, Cetoniidæ, Eumolpidæ, and Galerucidæ,—all flower and
foliage-haunting insects, yet bulky and of comparatively feeble powers of
flight. Again, all the large genera abundant in South Europe, which have
been mentioned above as absent from Madeira, are wholly apterous (or
without wings), and thus their absence is a most significant fact; for it
proves that in the case of all insects of moderate size, flight was essential to
their reaching the island, which could not have been the case had there been
a land connection. There are, however, one or two curious exceptions to the
absence of these wholly apterous European genera in Madeira, and as in
each case the reason of their being exceptions can be pointed out, they are
eminently exceptions that prove the rule. Two of the apterous species
common to Europe and Madeira are found always in ants' nests; and as ants,
when winged, fly in great swarms and are carried by the wind to great
distances, they may have conveyed the minute eggs of these very small
beetles. Two European species of Blaps occur in Madeira, but these are

house beetles, and are admitted to have been introduced by man. There are
also three species of Meloe, of which two are European and one peculiar.
These are large, sluggish, wingless insects, but they have a most
extraordinary and exceptional metamorphosis, the larvae in the first state
being minute active insects parasitic on bees, and thus easily conveyed
across the ocean. This case is most suggestive, as it accounts for what
would be otherwise a difficult anomaly. Another case, not quite so easily
explained, is that of the genus Acalles, which is very abundant in all the
Atlantic islands and also occurs in South Europe, but is always apterous. It
is however closely allied to another genus, Cryptorhynchus, which is
apterous in some species, winged in others. We may therefore well suppose
that the ancestors of Acalles were once in the same condition, and that some
of the winged forms reached Madeira, the genus having since become
wholly apterous.

We may look at this curious subject in another way. The Coleoptera of
Madeira may be divided into those which are found also in Europe or the
other islands, and those which are peculiar to it. On the theory of
introduction by accidental immigration across the sea, the latter must be the
more ancient, since they have had time to become modified; while the
former are comparatively recent, and their introduction may be supposed to
be now going on. The peculiar influence of Madeira in aborting the wings
should, therefore, have acted on the ancient and changed forms much more
powerfully than on the recent and unchanged forms. On carefully
comparing the two sets of insects (omitting those which have almost
certainly been introduced by man) we find, that out of 263 species which
have a wide range, only 14 are apterous; while the other class, consisting of
393 species, has no less than 178 apterous; or about 5 per cent in the one
case, and 45 per cent in the other.[8] On the theory of a land connection as
the main agent in introducing the fauna, both groups must have been
introduced at or about the same time, and why one set should have lost their
wings and the other not, is quite inexplicable.

Taking all these singular facts, in connection with the total absence of all
truly indigenous terrestrial mammalia and reptiles from these islands—even
from the extensive group of the Canaries so comparatively near to the
continent, we are forced to reject the theory of a land connection as quite

untenable; and this view becomes almost demonstrated by the case of the
Azores, which being so much further off, and surrounded by such a vast
expanse of deep ocean, could only have been connected with Europe at a
far remoter epoch, and ought therefore to exhibit to us a fauna composed
almost entirely of peculiar forms both of birds and insects. Yet, so far from
this being the case, the facts are exactly the reverse. Far more of the birds
and insects are identical with those of Europe than in the other islands, and
this difference is clearly traced to the more tempestuous atmosphere, which
is shown to be even now annually bringing fresh immigrants (both birds
and insects) to its shores. We here see nature actually at work; and if the
case of Madeira rendered her mode of action probable, that of the Azores
may be said to demonstrate it.

Mr. Wollaston has objected to this view that "storms and hurricanes" are
somewhat rare in the latitude of Madeira and the Canaries; but this little
affects the question, since the time allowed for such operations is so ample.
If but one very violent storm happened in a century, and ten such storms
recurred before a single species of insect was introduced into Madeira, that
would be more than sufficient to people it, as we now find it, with a varied
fauna. But he also adds the important information that the ordinary winds
blow almost uninterruptedly from the north-east, so that there would be
always a chance of a little stronger wind than usual bringing insect, or larva,
or egg, attached to leaves or twigs. Neither Mr. Wollaston, Mr. Crotch, Mr.
A. Murray, nor any other naturalist who upholds the land-connection theory,
has attempted to account for the fact of the absence of so many extensive
groups of insects that ought to be present, as well as of all small mammalia
and reptiles.

Cape Verd Islands.—There is yet another group of Atlantic islands which is
very little known, and which is usually considered to be altogether African
—the Cape Verd Islands, situated between 300 and 400 miles west of
Senegal, and a little to the south of the termination of the Sahara. The
evidence that we possess as to the productions of these islands, shows that,
like the preceding groups, they are truly oceanic, and have probably derived
their fauna from the desert and the Canaries to the north-east of them rather
than from the fertile and more truly Ethiopian districts of Senegal and
Gambia to the east. There is a mingling of the two faunas, but the

preponderance seems to be undoubtedly with the Palæarctic rather than
with the Ethiopian. I owe to Mr. R. B. Sharpe of the British Museum, a MS.
list of the birds of these islands, twenty-three species in all. Of these eight
are of wide distribution and may be neglected. Seven are undoubted
Palæarctic species, viz.:—Milvus ictinus, Sylvia atricapilla, S. conspicillata,
Corvus corone, Passer salicarius, Certhilauda desertorum, Columba livia.
Three are peculiar species, but of Palæarctic genera and affinities, viz.:—
Calamoherpe brevipennis, Ammomanes cinctura, and Passer jagoensis.
Against this we have to set two West African species, Estrilda cinerea and
Numida meleagris, both of which were probably introduced by man; and
three which are of Ethiopian genera and affinities, viz.:—Halcyon
erythrorhyncha, closely allied to H. semicærulea of Arabia and North-east
Africa, and therefore almost Palæarctic; Accipiter melanoleucus; and
Pyrrhulauda nigriceps, an Ethiopian form; but the same species occurs in
the Canaries.

The Coleoptera of these islands have been also collected by Mr. Wollaston,
and he finds that they have generally the same European character as those
of the Canaries and Madeira, several of the peculiar Atlantic genera, such as
Acalles and Hegeter, occurring, while others are represented by new but
closely allied genera. Out of 275 species 91 were found also in the Canaries
and 81 in the Madeiran group; a wonderful amount of similarity when we
consider the distance and isolation of these islands and their great diversity
of climate and vegetation.

This connection of the four groups of Atlantic islands now referred to,
receives further support from the occurrence of land-shells of the subgenus
Leptaxis in all the groups, as well as in Majorca; and by another subgenus,
Hemicycla, being common to the Canaries and Cape Verd islands.
Combining these several classes of facts, we seem justified in extending the
Mediterranean sub-region to include the Cape Verd Islands.

III.—The Siberian Sub-region, or Northern Asia.

This large and comparatively little-known subdivision of the Palæarctic
region, extends from the Caspian Sea to Kamschatka and Behring's Straits,