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THE

GEOGRAPHICAL AND GEOLOGICAL

DISTRIBUTION OF ANDATS

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Section =

ANGELO HEILPRIN

PROFESSOR OF INVERTEBRATE PALEONTOLOGY AT, AND CURATOR-IN-CHARGE OF,
THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA; PROFESSOR OF
GEOLOGY AT THE WAGNER FREE INSTITUTE OF SCIENCE, PHILADELPHIA;
MEMBER OF THE AMERICAN PHILOSOPHICAL SOCIETY, &C.

NEW YORK
PO APPLETON AND COMPANY
1887

Coryricnut, 1886,
By D. APPLETON AND COMPANY.

TO
PROFESSOR JOSEPII LEIDY, M.D., LL.D.,
PRESIDENT OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA, &C.,
WHOSE PROFOUND RESEARCHES HAVE SO LARGELY TENDED TO DEVELOP
THE SOIENCE OF BIOLOGY,

THIS VOLUME IS RESPECTFULLY DEDICATED,

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In the preparation of the following pages the author has
had two objects in view: that of presenting to his readers
such of the more significant facts connected with the past and
present distribution of animal life as might lead to a proper
conception of the relations of existing faunas; and, secondly,
that of furnishing to the student a work of general refer-
ence, wherein the more salient features of the geography and
geology of animal forms could be sought after and readily
found. The need of such a work has been frequently felt
and expressed. As far as he is aware, no work of that kind
has as yet appeared, and therefore, to a certain extent, this
publication stands alone in the field it is intended to cover.
Necessarily, much that it embraces can be found elsewhere,
and treated even at considerably greater length; but the mat-
ter is not contained under a single cover, and where a special
subject is expounded in extenso the treatment is usually too
exhaustive to permit of immediate use by the general reader.
This applies particularly to zoogeography. With reference
to geological distribution there is little connectedly written—
indeed, beyond what is found in text-books largely devoted
to cognate subjects, practically nothing. Moreover, what little
of connected literature on the subject we do possess is almost

Vill PREFACE.

entirely out of date, and in no way represents the present
status of the science.

The subject of geographical and geological distribution 1s
so vast that no full treatment of it could be expected in the
limited number of pages set apart for it in the present work.
The author has, therefore, been obliged to omit, or at least
largely ignore, the consideration of some of the less impor-
tant animal groups, and, while reccgnising the deticiencies
resulting from such omission, trusts that it will not detract
much from the general usefulness of the publication. The
plan of treatment followed in the early part of the book
(geographical distribution) is largely that so admirably un-
folded by Mr. Wallace, to whom, for the constant use of his
works, the author is under great obligations. He also wishes
to express his special indebtedness to the pioneer workers in
this field, Schmarda and Murray, whose writings have laid
the foundation of much of our existing knowledge in the
premises. No special mention need be made of the numer-
ous other authors who have contributed more or less exten-
sively to the subject under consideration, and whose works
have aided in the preparation of the present volume; to those,
collectively, the author likewise desires to acknowledge his
indebtedness.

A few words need be said in relation to the zoogeographical
regions that are recognised in this work, which differ essen-
tially from those generally adopted by naturalists. The rea-
sons for uniting the “Nearctic” and “ Palearctic” regions
ef zoogeographers into a single realm, designated, in accord-
ance with a suggestion by Professor Alfred Newton, of Cam-
bridge, the “‘ Holarctic,” are fully set forth in my paper “On
the Value of the Nearctic as one of the Primary Zoological
Regions,” published in the “ Proceedings of the Academy of
Natural Sciences of Philadelphia,” for December, 1882. Ob-

PREFACE. 1x

jections by Mr. Wallace and Professor Gill to the views there
formulated appear in “Nature” of March 22, and June 7,
1883, respectively, and my rejoinders to the criticisms of
these gentlemen in “Nature” of April 26, and the “ Proceed-
ings” of the Philadelphia Academy for November, 1883. To
these papers I must refer the reader for a purely technical
statement of the case. The classification of the “ Transition”
tracts is largely that which has been proposed by Forsyth
Major, in “ Kosmos” for 1884.

Acapemy or Naturay Sciences, Pamaprtrura, Oclober, 1886.

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PART IT
GEOGRAPHICAL DISTRIBUTION.

PAGE

General principles of zoogeography.—Faunal variation.—Faunas of isola-
tion.—Relations of past and prescnt faunas.—Origination of faunas

If.

Areas of specific distribution.—Generie distribution.—Distribution of fam-
ilies and orders.—Conterminous and discontinuous areas of distribu-
tion

Ill.

Conditions affecting distribution.—Climate.—Food-supply.—Barriers to
migration.—Migrations of mammals and birds.—Dispersal of amphib-
ians and reptiles.—Dispersal of insects and mollusks .

IV.

Zoological regions.—Holarctic realm.—Neotropical.—Ethiopian.— Orien-
tal.—Australian.—Polynesian.—Tyrrhenian, Sonoran, and Austro-
Malaysian transition regions . = z 5 . -

Distribution of marine life.—Nature of fhe deep-sea fauna.—Oceanic
pelagic fauna.—Littoral fauna.—Pelagice faunas of lakes. —Deep-lake
faunas . : : - : : - - :

ies

= 09

xu CONTENTS.

PART II.
GEOLOGICAL DISTRIBUTION.

i
PAGE

The succession of life.—Faunas of the different geological periods. . 138

Appearance and disappearance of species.—Reappearance.— Extinction. —
Persistence of type-structures. — Variation. — Geological breaks.—
Geographical distribution.—Climatic zones.—Synchronism of geo-
logical formaticns . : . : : : : : 0 ; . 181

PART Il.
GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

The present and past distribution of individual animal groups.—Forami-
nifera.—Corals. — Brachiopoda, — Mollusca generally.—Crustacea.—
Insecta, Arachmida, and Myriapoda_ . é ; . C 5 . 234

Il.

Distribution of the Vertebrata.—Fishes. peer aes eS —Birds.
—Mammals . . . 3 ees or Pei a) tesco

PARLE
GEOGRAPHICAL DISTRIBUTION.

General principles of zoogeography.—Faunas of isolation.—Relations of past
and present faunas.

EVERYWHERE upon the surface of the earth we meet with mani-
festations of animal life. The desert wastes, no less than the trop-
ical jungles, the bleak ice-fields of the frozen north, and the most
elevated mountain-summits—all have their faunas. The abyss of
the sea, no less than its surface, contributes its quota to the animal
world ; and in the atmosphere all around us, from the lowest stra-
tum not unlikely to the highest, the germs of the organic universe
lie everywhere scattered about. In what precise form or guise this
life first manifested itself, or how inert matter became endowed
with that potentiality which we recognise in vital energy, it seems
hopeless to attempt to determine. True science takes cognisance
of both fact and theory, but illusory speculation, whose ground-
work is a simple outgrowth of the imagination, must find a rest-
ing-place without its domain.

No one who has paid the smallest amount of attention to the
facts of nature as they present themselves can have failed to notice
certain peculiarities in the way of the distribution of life, which
do not always admit of an immediate or of a satisfactory inter-
pretation. Why, for example, one piece of country should differ
so essentially in its faunal aspects from another whose physical
characteristics are practically identical with its own; why the sec-
ond should differ from a third, and this, again, from a fourth—may
not appear comprehensible. Nor any the more comprehensible

2 GEOGRAPHICAL DISTRIBUTION.

may appear the circumstance that, in most cases, island faunas are
so eminently marked out from those of continental areas.

Another peculiarity in faunal distribution is presented in the
fact that, while certain animal assemblages enjoy an almost limit-
less or universal extension, others, again, without apparent reason,

are circumscribed within limits of the opposite extreme. The trav-
eller to the most distant shores not infrequently recognises objects
that are familiar to him as those of his native home, although pos-
sibly, in the interval of his journey, he has completely lost sight
of their existence, so different might have been the creatures that
successively met his gaze. ‘‘ When an Englishman travels by the
nearest sea-route from Great Britain to Northern Japan, he passes
by countries very unlike his own, both in aspect and natural pro-
ductions. The sunny isles of the Mediterranean, the sands and
date-palms of Egypt, the arid rocks of Aden, the cocoa-groves of
Ceylon, the tiger-haunted jungles of Malacca and Singapore, the
fertile plains and volcanic peaks of Luzon, the forest-clad mountains
of Formosa, and the bare hills of China, pass successively in review ;
till after a circuitous voyage of thirteen thousand miles he finds
himself at Hakodadi, in Japan. He is now separated from his
starting-point by the whole width of Europe and Northern Asia,
by an almost endless succession of plains and mountains, arid
deserts or icy plateaux, yet when he visits the interior of the coun-
try he sees so many familiar natural objects that he can hardly help
fancying he is close to his home. He finds the woods and fields
tenanted by tits, hedge-sparrows, wrens, wagtails, larks, red-
breasts, thrushes, buntings, and house-sparrows, some absolutely
identical with our own feathered friends, others so closely resem-
bling them that it requires a practised ornithologist to tell the differ-
ence. If he is fond of insects he notices many butterflies and a
host of beetles which, though on close examination they are found
to be distinct from ours, are yet of the same general aspect, and
seem just what might be expected in any part of Europe. There
are also, of course, many birds and insects which are quite new and
peculiar, but these are by no means so numerous or conspicuous
as to remove the general impression of a wonderful resemblance
between the productions of such remote islands as Britain and
Yesso:”%

* Wallace, ‘‘ Island Life,” p. 3.

FAUNAL VARIATION. 3

On the other hand, a journey of only very moderate duration
will frequently disclose the greatest diversity existing between con-
tiguous faunas. The traveller who starts east from the African
coast, and who has familiarised himself with the strange produc-
tions of the African continent, its elephants, giraffes, rhinoceroses,
hippopotami, lions, and antelopes, finds none of these in the island
of Madagascar ; the true monkeys have also disappeared, and in
their place he meets with forms of half-monkeys (lemurs), a group
of animals with which he will have already become acquainted
before leaving the mainland. Strange creatures, wholly unlike
anything previously known to him, now arrest his attention, and
he finds himself in the midst of what might be termed a peculiar
fauna. Likewise, if he leave the shores of Central America or
Florida for the Great Antilles, the same marked isolation of the
new fauna manifests itself. The larger forms of quadrupeds, such
as the jaguar, couguar, tapir, and peccary, are wholly wanting,
and even among the smaller and more numerously represented
mammalian types many oi the more prominent forms will be sought
for in vain. On the other hand, he will make the acquaintance of
entirely new groups of animals, some of which, like the Centetide,
have their nearest foreign representatives in regions removed by
nearly one-half the circumference of the globe. And this diversity
in the faunal type is found to permeate to a greater or less extent
all the individual groups, birds, reptiles, &c., of the animal king-
dom.

It might be rashly supposed that the distance separating the
regions under comparison would sufficiently account for the pecu-
liarities of their respective faunas, or the disparities separating
them; but distance alone, without a special relation binding to-
gether the principals between which it is supposed to act, can
effect nothing. We have, indeed, seen upon what a vast extent
of territory the British faunal facies is stamped, and were any
further proof needed of the inefficacy of distance, pure and simple,
as a prime factor in geographical distribution, we have but to
transport ourselves to the Malay Archipelago, and observe how
wonderfully diverse are the respective faunas on either side of the
very narrow (but deep) channel separating the islands of Bali and
Lombok from each other.

Mysterious as these various phenomena of distribution may ap-

4 GEOGRAPHICAL DISTRIBUTION.

pear, they yet have all their logical explanation. A quarter of a
century ago, when the doctrine of independent creation still held
sway over the minds of most naturalists, and when the organic
universe was reflected in the eye of the investigator as an incon-
gruous agglomeration of disjointed parts, there was, indeed, no
necessity for specially accounting for the facts, since they were
conceived to be such by reason of a previous ordination. Now,
however, when the full value of the evolutionary process is recog-
nised, and animate nature has come to be looked upon as a con-
crete whole, bearing special relations to its numberless parts, each
individual fact seeks its own explanation, which explanation must
of necessity stand in direct harmony with some previously observed
fact. When, therefore, we seek to unravel the tangle of zooge-
ography, and to harmonise its apparent incongruities, we must at
the outset admit that distribution, such as it is, is the outcome of
definite interacting laws — laws which stand in relation to each
other as absolutely as they do in any other field of action—and not
a hap-hazard disposition, as some would lead us to suppose, setting
all enquiry at defiance.

The naturalist who in the Western Hemisphere journeys south-
ward from the ice-covered fields of British America fails to notice
any very sudden or marked alternation in the character of the
faunas that successively meet his view. New features are being
constantly added, and old ones eliminated, but the interchange is
effected so gradually that it becomes dificult to determine the
limitations that properly define one fauna from another. The fur-
bearing animals of the far north send their representatives into
regions which border the habitats of the more exclusively tropical
species, or are succeeded by forms which differ but little from them.
The skunk, many of whose associates are animals of a distinctively
Arctic character, finds its way into Mexico, and the ermine, which
penetrates to the farthest northern point reached by mammals
generally, still lingers on in some of the Southern United States.
The Arctic fox is succeeded by the equally abundant types of the
grey and the red fox; and similarly, the polar bear is followed on
the one side of the continent by the grizzly, and on the other by
the black bear. Having descended into the middle temperate
regions, the traveller still finds about him mostly the forms with
which he has already become acquainted. But many of the more

FAUNAL VARIATION. 5

familiar types have either wholly disappeared, or are fast disap-
pearing. Such may be the musk-sheep, moose, stag, and reindeer,
which will have left as their successors the bisons and the various
species of smaller deer which range throughout the remainder of
the continent. The grey wolf of the northern forests breaks up into
a number of varietal forms more or less distinct from the typical
one, and is carried by the coyote into the heart of Mexico.

Farther to the south the traveller observes entirely new features
gradually appearing. In Arkansas he possibly meets with the pec-
cary, the first indigenous member of the pig family with which he
will have become acquainted; in Texas, with the armadillo, the
first of that group of animals, the Edentata, which, in the past and
present history of the South American continent, constitutes such
an important element in its faunas and, in the States adjoining the
Mexican Republic, with an abundant representation of the iguanid
lizards, which, by their numbers, so eminently typify the follow-
ing region of the tropics. There are as yet neither monkeys, ta-
pirs, nor guinea-pigs, but the first appear in Southern Mexico, the
second in Central America, and the last in Venezuela or Guiana.
The traveller is now in the region of the Equator, and surrounded
by an association of animal forms most of which were unknown to
him when he entered upon his journey, and which in many respects
depart so widely from those with which he was familiar at his start-
ing-point as to constitute a distinct fauna. There is no longer
either wolf, fox, or catamount, beaver or musk-rat, and of the spe-
cifically important group of the hares or rabbits but a single species
remains, The solitary species of bear is so different from its north-
ern cousins as to be regarded by some naturalists as the type of a
distinct genus.

The contrast between the successive faunal changes observed on
the north and south journey and the faunal identity which so aston-
_ ishes the traveller whose journey is directed eastward from Eng-
_ land to Japan is very great. And yet if the traveller from Britain,
instead of proceeding due eastward, were to shape his course a
few degrees to the south, much the same kinds of changes as he
noticed on his American trip would again present themselves.
Along the shores of the Mediterranean he would no longer, or only
at rare intervals, meet with his associates of the Arctic north; on
the southern slopes of the Caucasus the tiger, and in Arabia the

6 GEOGRAPHICAL DISTRIBUTION.

camel, gazelle, and ostrich, would present to him certain features
of a fauna which was in the main unknown to him; in India the ele-
phant, lion, and rhinoceros, and other curious denizens of the jun-
gle, the python and crocodile, and the numerous birds of resplendent
plumage, would probably crowd from his memory the forms of the
creatures ordinarily most familiar to him, and lead a passage to the
ultimate goal of his journey, Australia, where he would meet with
the most singular and most distinctive fauna on the surface of the
earth.

Much nearer to his northern home—on opposite sides of the
Mediterranean—and with much less travelling, the naturalist will
discern scarcely less well-marked faunal differences or peculiarities.
To account for the anomalies which the facts of distribution present
is the still unsolved problem that is put before the zoogeographer.

Granting, with the doctrine of evolution, that all the complex
assemblages of existing animal forms are modified derivatives from
previously existing forms, and that these are ultimately to be traced
back to some common ancestor, it must of necessity follow that any
given fauna will depend for the degree of its peculiarity, whether
great or small, upon the amount of modification, relative to any
other fauna, which it will have undergone. And this modification
can be effected in two ways: by inherent modification of the indi-
vidual types composing the fauna, and by intermixture with, or
immigration from, contiguous or neighbouring faunas. In both
cases, manifestly, isolation or its opposite, union of habitation, will
constitute the governing factor in determining the amount of varia-
tion. A region that is broadly separated from all others will, natu-
rally, tend to develop a fauna distinct from any other, since the
progressive modifications in its constituent faunal elements must ul-
timately lead to divergence; and the greater the period of isolation
the greater, of necessity, will be the amount of this divergence, or
the more pronounced the faunal individualisation. Hence it is that
in the greater number of the more distantly removed island groups,
or in those which are separated by more or less impassable barriers
from the nearest land-mass, we meet with such highly specialised
faunas. The Galapagos Islands, for example, as will be more fully
illustrated farther on, have a fauna very distinct from that of any
part of South America, although removed from it by a distance of less
than seven hundred miles. The birds are quite distinct, and so are

ISLAND FAUNAS. 7

the reptiles, insects, and land mollusks. The island of St. Helena,
in the South Atlantic, and the Sandwich Islands, in the North
Pacific, present us with similar instances of faunal specialisation,
and to a less extent, also, the group of the Azores. In the case of
these last, which lie in the course of the storm-winds, a considerable
intermixture has been effected with the faunas of Western Africa
and Europe, for we find that by far the greater number of the resi-
dent iand-birds are inhabitants of those two continents as well.
The fact that there are so very few peculiar forms is proof either of
a recent separation of the islands from the mainland—not sufficient
time having been allowed for the development of new species—or
of arecent or repeated peopling with old forms from the continents.
Even irrespective of considerations connected with the physical
geography or geology of the region, it would naturally be inferred,
from the prevalence of in-blowing storm-winds, and the known fact
that certain birds are transported hither, that the second supposi-
tion is the correct one; and that this is the true explanation is
proved by evidence of a very positive character furnished by some
of the other groups of animals. Thus, the land-Mollusca, which
in their distribution are not so readily affected by aerial currents,
are eminently distinguished from those of either Europe or Africa,
or of any other continental land-mass, proving in their case a long-
protracted period of isolation. Further, there is not a single species
of fresh-water mollusk known in the entire group! The Bermuda
Islands, which are about equally distant from the mainland, occupy
a nearly analogous position with respect of their fauna; that is, par-
tial interchanges have been effected with the fauna of the American
continent.

In all these cases, necessarily, the amount of faunal specialisation
will be the index of the period of isolation. Where faunal immi-
gration from a foreign region takes place it not only checks the
development of a newly-forming fauna, by infusing into it an ele-
ment that does not properly belong there, but also prevents in a
measure that variation among individuals which might otherwise
obtain. The case of the bobolink of the Galapagos Islands is a
well-known example of this kind. It alone, of about thirty species
of land-birds inhabiting those islands, is considered to be indis-
putably identical with any form occurring on the mainland; hence
it is concluded that this is about the only species of South American

8 GEOGRAPHICAL DISTRIBUTION.

bird that ever visits the islands, for, if the case were otherwise, it
would be incredible that no more common forms should have been
detected there. But the fact that the bobolink has remained abso-
lutely identical with the common form of South America, whence,
doubtless, most of the species of Galapagos birds have been derived,
while all the other birds of the island group have undergone more
or less modification since the islands were first tenanted, proves that
variation in its case has been prevented by the perpetuation of nor-
mal characters through interbreeding with the continental migrants.
In other words, the breed has been kept true. Were the migrations
of the visitors checked or interrupted, there can be little question
that the island breed of bobolinks would undergo the same kind
of modification which distinguishes the other birds, and which has
developed in them new specific er varietal types. In the conti-
nent of Australia, again, we meet with the most remarkable exam-
ple of a highly specialised fauna being developed as the result of
long-continued isolation. Of all the varied mammalian forms which
elsewhere crowd the surface of the earth we have here but the
merest trace, for, with the exception of the rodents and bats, none
of the ordinary orders—Carnivora, Ungulata, Insectivora, &c.—are
represented.* And even of the rodents there is but a single family,
that of the mice (Muridx). On the other hand, the implacental
mammals—kangaroos, wombats, duck-bill—whose only non-Aus-
tralian representatives are the American family of opossums (Didel-
phidee), acquire here a wonderful development, and exhibit a diver-
sity of type-structure not met with in any other order of mammals.
Now, the animals of this class, or such as might be considered most
nearly allied to the marsupials, are the first of the Mammalia to ap-
pear in geological time, and they alone have thus far been detected
in any of the deposits (Triassic, Jurassic) of the middle geological
period, or Mesozoic era. They constitute the most primitively or-
ganised members of their class, and probably stand not far removed
from what may ultimately be proved to be the bottom of the mam-
malian series.

In order to explain the anomalies of the Australian mammalian
fauna we must have recourse to the hypothesis of isolation, for in

* The Australian wild-dog, or dingo, may prove to be indigenous, in which
case it would represent the Carnivora.

AUSTRALIAN FAUNA.:- - 9

no other way could we satisfactorily account for the remarkable
development of the marsupial types, and the almost total absence
of the commoner forms that are elsewhere so abundant. The
oceanic barriers have evidently prevented that diffusion of species
which would otherwise have sufficed to render the Australian fauna
cosmopolitan in character. That this isolation, further, of the con-
tinent has been of very great duration is proved by the long period
of time, dating from the Cretaceous epoch, during which the
most diverse forms of mammalians have existed, and the high
specialisation that its own fauna has acquired. It may appear not
a little surprising, in view of what has preceded, that two groups of
animals, so widely removed from the rest of the Australian mam-
malian fauna as are the mice and bats, should yet constitute a
part of this fauna. In the case of the bats it is not difficult to ac-
count for their occurrence in the region in question, since their
powers of flight have enabled them to overcome such obstacles
as to other animals might have proved true barriers to migration.
The mice, on the other hand, whose disposition to gnaw into, and
conceal themselves among, timber of all kinds, is well known, may
have found their way hither from the Asiatic continent or its ad-
joining islands through the intermedium of floating masses of vege-
tation. Much more inexplicable is the occurrence of the single
non-Australian family of marsupials, the opossums, on the American
continent, which is removed by a continuous water-way of several
thousands of miles, when not a single member of the entire sub-class
of implacental mammals is found on any other part of the earth’s
surface outside the Australian region. The hypothesis that land
connection by way of the Antarctic region at one time existed be-
tween Australia and South America, and, possibly, also Africa,
may or may not be true, but the evidence that has thus far been
adduced tending to show that by such connection a transferrence
of one section of the Marsupialia has been effected from one con-
tinent to the other is certainly very slim. Yet it is by no means
impossible that such may have been the case. The Edentata—
armadillos, ant-eaters, pangolins—whose home is preeminently the
two great continents of the Southern Hemisphere, and which barely
trespass north of the Tropic of Cancer, and the struthious birds,
like the rhea, ostrich, and cassowary, offer equal perplexities in the
way of an explanation of their anomalous distribution with the
9 :

10 GEOGRAPHICAL DISTRIBUTION.

marsupials, and they have likewise been considered to afford proof
of a land connection such as has been indicated. A serious diffi-
culty, however, that lies in the way of this explanation is the
important fact that none of the characteristic African or South
American mammals are found in Australia, for it might justly be
contended that if a migration or transferrence was effected in one
direction, it could have been effected in the opposite direction as
well. But that such reciprocal distribution did not obtain is very
nearly certain. It may, indeed, be assumed that at the time of a
possible Australian migration the extremities of the southern con-
tinents were not yet inhabited; but this is very unlikely. Or, it
may be further assumed, with Riitimeyer, that the animals under
consideration had a polar origin, and that they were distributed
northward along continental lines that possibly now lie buried
beneath the sea; but positive evidence in this direction is still
wholly wanting. An element in the problem which very materi-
ally narrows the issue is the circumstance that marsupial remains
have been found in the temperate regions of the Northern Hemi-
sphere, and in both Europe and North America in deposits as an-
cient as the Triassic period. In this upper tract, therefore, we
find a possible and more probable clue towards the explanation of
the existing distribution of the animals in question ; and if it be
objected that some such living forms ought still to be found in
the connecting region, the fact, nevertheless, remains that they did
there once exist, but have since become largely extinct.

It will be evident that the key to the solution of the more
marked peculiarities of modern distribution must be sought in the
records of the past, for in the comparison between existing and
preexisting faunas alone can we expect to determine the condi-
tions upon which present faunas were established, and to ascertain
the dates of their respective appearances or antiquity. In most
regions of the earth’s surface a most intimate relationship links
together the existing fauna and the fauna of the geological period
or periods immediately preceding. The Pliocene and Post-Pliocene
marine shell-fish faunas of the Western United States are practically
identical with the equivalent fauna of the (modern) adjoining seas;
the Post-Pliocene mammals of Britain are such as still roam about
the land, although they include numerous forms which no longer
exist there; in India a large proportion of the mammalian types

TERTIARY FAUNAS. iil

that inhabit the region are already represented in deposits of the
early Pliocene period; and in Australia the abundant remains of
Marsupialia amply testify to the identity of character which unites
the faunas of the past and present periods. A certain amount of
antiquity is thus established for the several regional faunas. The
farther back in time we proceed, however, the less pronounced ap-
pear the common characteristics of past and present periods; and,
finally, they disappear almost altogether. Thus, the Eocene shell-
fish fauna of the Atlantic coast of the United States and of France
and Great Britain is very unlike that of the seas adjoining those
regions at the present day, although, in a measure, it finds its ana-
logue in the corresponding fauna of the eastern tropical seas. The
Miocene mammals of the American continent are almost wholly
unlike those which now inhabit the region, and what little simi-
larity still remains completely vanishes with the animals of the
more ancient Eocene period. And the same holds good with the
European Tertiary fauna. Yet there are a number of existing
types which in their own region can be traced through a series
of progressive modifications to ancestral forms more or less unlike
them, which belong to a comparatively remote geological epoch.
The horse of the Old World, for example, has been traced through
a number of intermediate forms to the Old Tertiary Paleotherium,
one of the most abundantly represented mammalian genera of the de-
posits of Western Europe. The deer of the same region finds early
ancestors in the horned and hornless species which occur fossil in
the Miocene deposits of France and Germany; and not unlikely the
wolf and fox see their progenitors among the early members of the
canine race, whose remains have been traced to the Oligocene, and
not impossibly also to the Eocene period. In so far as these ani-
mals are concerned, therefore, we have direct evidence of a fauna
of considerable antiquity developing in place. In other cases, how-
ever, evidence of a very opposite character is often presented; that
is to say, faunas, or their components, are very frequently shown
to be in a given region of only brief duration. Thus, although
bears are very plentiful at the present time in the North American
continent, they are not known to have existed there before the last
geological period, the Post-Pliocene. And the same is true of the
members of the ox-family (Bovide)—most of which are, indeed,
not represented at all as fossils—of which North America possesses

12 GEOGRAPHICAL DISTRIBUTION.

five, in the main, widely-distributed species : two antelopes, two
sheep (including the musk-ox), and the bison. The question as to
how these animals obtained a foothold in the region which they
now inhabit, whether they originated there as derivatives from
previously-existing forms, or were introduced as migrants from
some land-mass lying without their domain, can only be deter-
mined by a reference to the still earlier fauna of not only this, but
of other regions as well. In the case of the bears, for example, no
immediate ancestors of the tribe have thus far been discovered in
the Western Hemisphere antedating the Post-Pliocene epoch; on
the other hand, in the Eastern Hemisphere—Europe—the remains
of such animals, and of the true bears themselves, are abundant in
deposits of the earlier Pliocene age. Hence, the assumption appears
almost unavoidable that the North American fauna received its
ursine contingent from the Old World. The same may or may not
be also true of the American Bovide; but the determination of
this question is made difficult, or impossible, through the fact that
at least two of the genera—Ovibos and Bison—occur fossil in the
Post-Pliocene deposits, and there only, of both the Old and the
New World, and consequently appear in the two hemispheres as
being of approximately equivalent age. Yet the fact that neither
goats, sheep, oxen, nor antelopes have thus far been discovered
fossil on the North American continent, while their remains are suf-
ficiently abundant in the deposits of Eurasia (Europe-Asia) of Post-
Pliocene or even much older age, would seem to indicate that the

true home of the Bovide is the Old World, whence, by gradually
' spreading, and through the facilities afforded them in the way of a
northern land connection, they eventually came to occupy a con-
siderable portion of the New World as well. The giant sioth-like
forms, such as the Megalonyx, Megatherium, and Mylodon, which
in North America are associated with the remains of animals of
indisputably Post-Pliocene age, occur in South America in an older
formation, the Pliocene, and thus seemingly represent an. invasion
of the north from the latter continent. This conclusion appears
further borne out by the circumstance that the Southern Hemi-
sphere is the home of the animals of this class, and that, with
scarcely a single exception (Moropus, ? Morotherium) no edentate
form has thus far been discovered in any North American deposit
antedating the period which represents the development of the

FAUNAL MIGRATION. 13

South American forms. Similarly, the extinct proboscideans, mam-
moth and mastodon, are of later date in America than in Eurasia,
and are in all probability to be traced back to the latter region for
the place of their birth.

The countries of the Old World present to us perhaps no less
direct evidence as to the origination of, or the lines of migration
taken by, specific groups of organisms. The European mammalian
fauna is at the present time not very unlike in its general features
that of North America, but in the geological period immediately
preceding the present one it numbered a host of forms wholly dif-
fering from anything known to have existed in the corresponding
period of American history, and, indeed, quite different from any-
thing now inhabiting Europe. Such, for example, were the mam-
moth, African elephant, hippopotamus, African lion, leopard, the
spotted and the striped hyena, several species of rhinoceros, & ,
forms the greater number of which are at the present day associated
with the region lying south of the Mediterranean. The question
that here presents itself is one, perhaps, that cannot be fully an-
swered, but yet one whose partial solution is made very nearly certain.
Did this fauna become suddenly exterminated, through some agency
or other, in the region inhabited by it, or did it migrate elsewhere?
There can be but little doubt that both conditions took place. The
mammoth and the several species of (fossil) rhinoceros are now all
extinct, and there is every reason to believe that their tribes per-
ished gradually, without their having accomplished much migration
immediately preceding final extermination. The case is, however,
different with the other forms, for the fact of their inhabiting the
African continent leads one to suspect that they may have found
their way thither by way of some land connection no longer remain-
ing. That such a connection uniting the two continents did exist
within a comparatively recent geological period, permitting of an
interchange of the respective faunas, is certain, as is proved by the
numerous ties which bind together the faunas of the opposite shores
of the Mediterranean. The Barbary ape of the Rock of Gibraltar
inhabits Morocco, while the ichneumon of Spain, the porcupine of
Italy, and the fallow-deer of the south of Europe generally, are all
forms inhabiting the north of Africa as well. These animals evi-
dently crossed over the intervening sea by some route or other, and,
as has already been stated, in comparatively recent times, otherwise

14 GEOGRAPHICAL DISTRIBUTION.

while the type-forms represented on the opposing shores might have
been alike, the species would have almost undoubtedly differed.
Equally positive proof in this direction is furnished by the similari-
ties presented in the reptile and amphibian faunas. The shallow-
ness of the channel separating Spain from Morocco renders it prac-
tically certain that one such connecting land-mass occupied the
position of the present Straits of Gibraltar. On the other hand, the
finding of remains of several species of elephant in Sicily and Malta
is almost proof positive of a second connection having been formed
between Italy and Tunis. An elevation of the present bed of the
sea a few hundred fathoms would bring about this result. The
Mediterranean would then consist of two land-locked basins. But,
doubtless, many of the other islands besides Sicily and Malta were
united with the mainland, for otherwise it would be impossible to
explain the distribution of several modern animals, the moufflon,
for example, which is found in Sardinia, Corsica, Crete, and the
mountains of Greece.

Granting this connection between Africa and Europe, it appears
more than likely that the principal disturbing element which reacted
upon the Post-Pliocene European fauna, the great northern ice-sheet
and the accompanying cold of the glacial period, rather than caus-
ing the complete or sudden extermination of the receding fauna,
compelled it to migrate over into regions of a more congenial cli-
mate. That such was the fate of many of the forms there can be
no reasonable doubt. The African continent thus became stocked
with its existing fauna largely from the more temperate northern
regions. But there is every reason to believe that these same south-
ward retreating forms were in great part primarily introduced into
Europe from Africa, and over the same routes by which the later
southerly migration was effected. Concerning the origin of the
African fauna itself we possess little precise information. The
paleontology and geology of the region are so imperfectly known
that we possess as yet no basis for satisfactory deductions. The
absence of sufficient data naturally renders uncertain all speculation
relating to the late European fauna as well. It may be considered
highly probable, however, that many of its characteristic elements
have been derived from the region about India, where a considerable
antiquity, extending back to the Miocene or early Pliocene period,
is proved for at least a number of the more prominent types. Seve-

ORIGINATION OF FAUNAS. 15

ral of the antelopes have related, and apparently ancestral, forms
in the Miocene deposits of Greece (Pikermi), which also contain a
form not very far removed from the giraffe (Helladotherium), and
a species of true giraffe itself (Camelopardalis Attica), so that
possibly a contingent of the African fauna may have been derived
from this region. Whether the southern or Ethiopian portion of
the continent was at one time since the introduction of the placental
Mammalia completely severed from the northern part or not there
are as yet no means for determining. That Madagascar at one time
formed part of the continent is indisputably proved by the character
of its fauna ; but that its subsequent isolation is of very ancient
date is conclusively shown by the complete absence of all the more
distinctive Ethiopian placental mammals.

The few examples that have been cited in illustration of the
appearance and disappearance of faunas are sufficient to show the
character of the investigation that is open to the zoogeographer.
While from the data that we now possess much can be done towards
shaping our suppositions, it must be confessed that our knowledge
is still much too limited to permit of very satisfactory conclusions
being drawn therefrom. The principal danger that besets any in-
vestigation in the direction here outlined arises from the very
natural assumption that the greater antiquity in any one region over
another of a given type of animal indicates its prior appearance
there, and migration thence to one or more secondary regions.
This assumption might be well founded if we were only half con-
versant with the past paleontological histories of the regions under
consideration; but where at best our knowledge is still very imper-
fect, as it is in the case of Africa, Asia, and South America, it would
be, to say the least, highly injudicious. For what evidence have
we that animal types not yet found, or dating back only to a com-
paratively recent period, might not some day be turned up in abun-
dance, and in deposits of such age as to completely overthrow any
deductions that may have been based upon their supposed non-
occurrence? A single illustration of this kind will suffice. Pale-
ontologists are in the habit of considering the camels a New World
family, which by migration finally occupied the region which it
now inhabits. This conclusion is based upon the circumstance that
numerous cameloid forms (Pliauchenia, Procamelus, Protolabis,
Poebrotherium) carry this line of animals back in the North Ameri-

16 GEOGRAPHICAL DISTRIBUTION.

can continent to the early Miocene period, whereas such types are
almost wholly wanting in the range of equivalent deposits of the
Old World. Yet, if this is the true history of the family, it is
certainly a surprising fact that the true camel itself (Camelus),
which is entirely unknown on the American continent, should al-
ready be found fossil in the Miocene (or older Pliocene) deposits
of India. Nor is it at all unlikely that ancestral forms leading up
to this type may yet be found in ities: of still older age hereafter
to be discovered.

Areas of specific distribution.—Generic distribution.—Distribution of families
and orders.—Conterminous and discontinuous areas of distribution.

It is a fact of general observation that a given species of animal
is so restricted in its range as to entitle the geographical area princi-
pally occupied by it to be considered as its home. This home may
be limited in its extent toa very narrowly circumscribed area, possibly
not embracing more than a few square miles, or even less, or it may
spread out to dimensions coextensive (or nearly so) with the conti-
nental boundaries; or, finally, it may comprise considerable portions
of two or more continental areas combined. As examples of animals
having a very restricted geographical distribution may be cited the
Pyrenean water-mole (Myogale Pyrenaica), a small insectivore found
only in a very few localities of the northern valleys of the Pyrenees,
and a species of buschbok (antelope, Cephalophus Natalensis),
whose habitat is the region about Port Natal, South Africa. Arc-
tomys caudata, one of the Asiatic marmots, is confined to the ele-
vated valley of Gombur, in India, and to heights exceeding 12,000
feet. Of birds, whose powers for self-distribution are much more
fully developed than among mammals, we have equally pointed
examples of localisation. The brown-and-white cactus-wren (Cam-
pylorhynchus albibrunneus) is confined exclusively to the Isthmus
of Panama, where its range is also somewhat limited; the Bornean
yellow-bulbul (Otocampsa montis) has only been met with on the
peak of Kina-Balu, in Borneo; and the red bird-of-paradise (Para- j
disea rubra) only within the narrow limits of the island of Waigiou,
lying to the northwest of New Guinea. The most remarkable in-
stances of localisation are probably afforded by the humming-birds,
several species of which would seem to be restricted respectively to
the volcanic peaks of Chimborazo and Pichincha, in the equatorial

18 GEOGRAPHICAL DISTRIBUTION.

Andes, and to the extinct crater of Chiriqui, in the province of
Panama, Colombia. The Loddigesia mirabilis, one of the most
beautiful of the Trochilide, has been observed thus far only at
Chachapoyas, in the Peruvian Andes, and even there it occurs so
rarely as to have been obtained but once during the period of forty
years following its first discovery.?

Too much stress should not, however, be laid upon what would
appear to be the absolute localisation of a species, since such sup-
posed localisation is frequently only the expression of our defective
knowledge in the premises. In the case of the famous South
American oil-bird, or guacharo (Steatornis Caripensis), for example,
which was for a long time considered to inhabit solely a cave near
Caripé, in the province of Cumana, Venezuela, more recent research
has revealed a comparatively broad area of distribution, which
embraces Sarayacu and Caxamarca in Peru, Antioquia in Colombia,
and the Island of Trinidad. The garden-mouse (Mus hortulanus),
which for some twenty years was known only from the botanic gar-
dens of Odessa, Russia, has been found in abundance in Kaschau
and several other towns of Northern Hungary.* So, likewise, in
the case of the anthropoid apes of the genus Troglodytes, which
were formerly supposed to be restricted to the western regions of
the African continent, but which the more recent explorations of
Schweinfurth, Von Heuglin, and others have shown to inhabit East
Central Africa as well.

Of species having a very broad distribution—excluding such as
have been transplanted through the agency of man—may be cited
the African elephant, whose domain extends over the greater part
of the African continent south of the Sahara Desert ; the tiger,
whose habitat embraces the entire east and west extent of Asia,
from the Caucasus to the Island of Saghalien; and the ermine, which
is found throughout the greater portion of the temperate and boreal
regions of the Northern Hemisphere. The leopard ranges over entire
Africa and throughout most of Southern Asia, having, with perhaps
the exception of the common European wolf, whose identity with
the various forms of American wolves is conceded by many natural-
ists, and some of the smaller carnivores, the most wide-spread dis-
tribution of any mammalian species. There is but little question
as to the identity of the North American and European species of
brown-bear, Arctic fox, glutton, ermine, weasel, elk, reindeer, and

DISTRIBUTION OF SPECIES. 19

beaver,® all of which have, consequently, a very extended range.
The American panther or couguar (Felis concolor) inhabits the
territory included between Canada and Patagonia, an extent cover-
ing upwards of one hundred degrees of latitude, which probably
represents the greatest north and south range of any mammal.

As might naturally have been expected from the greater facili-
ties for dispersion, we find many more marked instances of broad
specific distribution among birds than among mammals. Indeed,
when we consider with what apparent facility certain birds accom-
modate themselves to the varying conditions of atmospheric pres-
sure and climatic changes, and the readiness with which they trav-
erse broad expanses of the oceanic waters—e. g., the North Atlantic
between Ireland and Labrador—it might at first sight appear as
though there ought to be, at least in many cases, no absolute limit
to their distribution ; yet, from our present knowledge, it may
safely be affirmed that there exist but very few species of birds
which are in any way cosmopolitan. The fish-hawk (Pandion
haliaétus), with probably the most extensive range of any known
bird, inhabits the greater portion of all the continents, with the
possible exception of Australia, where its place appears to be sup-
plied by a closely-allied (and by many ornithologists considered
identical) species, the P. leucocephalus. Scarcely, if at all, less
extensive is the range of the common peregrine falcon (Falco com-
munis or peregrinus) and the barn-owl (Strix flammea), the former
of which is distributed, according to Professor Newton, from ‘‘ Port
Kennedy, the most northern part of the American continent, to
Tasmania, and from the shores of the Sea of Okhotsk to Mendoza, in
the Argentine territory,” and the latter, according to Sharpe, over
the entire world, with the exception of New Zealand, and many
island groups of Oceania, Malaysia, &c. The common American
raven (Corvus corax) has, likewise, a very broad distribution, its
range extending from Mexico into the far north, over the whole of
Europe and Northern and Central Asia, as far east as the Island of
Saghalien.

The fishes present scarcely less well-marked examples of broad
distribution; but in such aquatic forms the physical conditions of
the medium which they inhabit offer far less obstacles to a very
general diffusion than are to be encountered in the case of terrestrial
animals. The same holds true with other aquatic animals capable

20 GEOGRAPHICAL DISTRIBUTION.

of self-locomotion, and, indeed, in the case of those pelagic forms
whose dispersion or ‘‘ migration” is less a matter of volition than
the result of an interaction of extraneous physical causes there
would seem to be no barriers set to a practically universal distribu-
tion. But here, too, Nature has set a limit to the possibilities of
migration, and, therefore, even among those lower forms which
might be considered best adapted for withstanding the varying
physical vicissitudes of their surroundings we meet with but very
few species whose distribution might be said to be in any way
cosmopolitan. The free-swimming pteropods, or winged - Mol-
lusca, and medusoids, although exhibiting individual examples
of very broad distribution, are still more or less restricted specifi-
cally to well-defined oceanic areas, whose boundaries may in a
measure be dependent upon the prevalent surrounding water-
currents. Shells of the Spirula Peronii, a member of the two-gilled
order of cephalopods, are met with almost all over the oceanic bor-
ders, as well in the temperate as in the tropical zones, but, owing
to the extreme rarity of the animal itself, which has been observed,
perhaps, but a half-dozen times, it is impossible to say what the
exact, or even approximate, range of the species is, and, conse-
quently, of how much of the area of the distribution of the shell it
partakes. The common form of argonaut (Argonauta argo) is found
in the tropical parts of the Atlantic, Pacific, and Indian oceans, and
in the Mediterranean Sea, and it has been met with as far north
in the Atlantic as the New Jersey coast, and as far south as the Cape
of Good Hope. The animal might, therefore, be said to be almost
cosmopolitan.

It may be laid down as a fundamental law in geographical dis-
tribution that the areas inhabited by a given species are continuous
with each other; in other words, we do not find, except at rare
intervals, and under peculiar circumstances, the same species of
animal inhabiting distantly-separated localities, in the interval be-
tween which no individual of the species is to be met with. Thus,
in the entire range of the leopard there occurs no district of any
significance where the animal may not be confidently looked for,
and which would negatively tend to render its distribution discon-
tinuous. And the same may be said of the hundred or more
degrees of latitude prowled over by the couguar, an animal whose
home is at one place the lowland forests, at another the elevated

AREAS OF HABITATION, 21

mountain plateaus, and at a third the grassy savannas and rolling
plains. Naturally, in the case of such animals as are dependent
for their existence upon certain physical peculiarities of their en-
vironment, or upon particular conditions of food and climate, we
shall meet with local areas scattered through the region of dis-
tribution of a given species where no individuals of that species
are to be met with, an apparent discontinuity being thus _pre-
sented. For instance, such denizens of the forest as the South
American monkeys and the sloths will but very exceptionally be
found anywhere else than in their forest homes, and, therefore, the
partial destruction of this forest, or its invasion by a grassy savan-
na, will tend to render the ‘‘ home ” of those animals discontinuous.
Possibilities of such, or a similar, discontinuity may likewise arise
in the case of the animals of the plains, marshes, and deserts, since
the physical aspects of the earth’s surface are constantly subjected
to vicissitudes of greater or less magnitude, and, as a matter of
fact, we find numerous instances where, in an extensive range,
particular animals are restricted in their habitats to certain favoured
spots or localities. But in all or most of such instances a former,
and comparatively recent, continuity of area, or possibility of mi-
gration from one locality to another, can be proved. The chamois,
whose range embraces the entire east and west extent of Southern
Europe, is found almost exclusively on the higher mountain sum-
mits—the Pyrenees, Alps, Carpathians, Caucasus, and the moun-
tains of Greece—and would appear, therefore, to occupy several
widely-removed habitats. But there can be no reasonable doubt
that the peculiar distribution of this animal is the outcome of
migration from a central home. The hippopotamus is found in
the Nile, Niger, Senegal, and most of the larger rivers of South
Africa, between which stretch vast areas where no individuals of
the animal have ever been found—regions untenantable by reason
-of their aridity; but here, as in the case of the chamois, there can
be no doubt that a migration or diffusion did take place at a time
when the physical aspects of the country were favourable for such
a dispersion, and were, consequently, different from what they
are at present. One of the most remarkable instances of areal dis-
continuity among mammals is that exhibited by the variable hare,
whose home, in the Old World, is Eurasia north of the fifty-fifth
parallel of latitude. The animal reappears, after skipping the low-

22 GEOGRAPHICAL DISTRIBUTION.

lands of Central Europe, in the Pyrenees, Alps, and the Bavarian
Highlands, and again in the Caucasus, the last region isolated by
fuily one thousand miles of non-inhabited country. Equally strik-
ing examples were supposed to be afforded by the fresh-water seals
of Lake Baikal and the brackish-water species of the Caspian, which
were considered to be identical with the northern Phoca feetida and
P. vitulina respectively, but more careful study has shown this
identification to be erroneous.* The critical studies made by Mr.
Seebohm of the Central and East Asiatic faunas have disclosed
a number of extraordinary instances of discontinuous habitation
among birds. One of these is exemplified in the case of a South
European variety of the common marsh-tit (Parus palustris), which
reappears in an undistinguishable guise in China, although in an
intervening tract of some four thousand miles (east of Asia Minor)
the variety is entirely wanting, being replaced by one or more
closely related forms. Ceryle guttata, a spotted king-fisher, appears
to be confined to Japan and the Himalaya Mountains, being com-
pletely wanting in China; and the same is true of a species of
crested eagle (Spizaétus orientalis), with the exception that its
range embraces the Island of Formosa. Similarly, we have two
species of birds, the rufous-breasted fly-catcher (Siphia superciliaris),
and the Darjeeling wood-pigeon (Palumbus pulchricollis), which
are absolutely confined to the Himalayas and the Island of Formosa.

But while individual cases of species inhabiting discontinuous
areas do present themselves, they are of comparatively rare occur-
rence, and the general law of regional continuity may be recognised.
In a region occupied by a given species of animal there is usually
an area which is par excellence more thickly inhabited than any
other, and which may, consequently, be termed the ‘‘ metropolis”
of that specics. From this metropolis there is in most cases a
radial distribution of the individuals of the species, with a thinning
out towards the periphery. Distinct species of the same genus
rarely have coincident geographical distributions; in other words,
they rarely occupy precisely the same areas, but more generally
these areas, if at all continuous, overlap each other to a greater or
less extent. This fact is beautifully exemplified in the case of the
American hares, which are represented by some eleven species, and
about as many well-marked varieties. Commencing at the far
north, we have the polar or variable hare (Lepus variabilis or L.

OVERLAPPING AREAS. 20

timidus, var. Arcticus), whose range extends from the Arctic coast
southward to Newfoundland, and in the interior to Fort Churchill,
on Hudson’s Bay. Along its southern confines it meets and slightly
overlaps the boundaries of the northern varying hare (L. Ameri-
canus), which, in its several geographical varieties, is distributed
from the Barren Grounds in the north southward to a zone which
corresponds generally with the isotherm of 52° F. On the Atlantic
coast region, the southern limit of this species appears to be Con-
necticut; along the line of the Appalachian highlands, Virginia (or
possibly North Carolina); and in the Rocky Mountain region, New
Mexico. Lepus Americanus is found throughout the northern parts
of nearly all the northern tier of States interposed between the
Missouri and the Atlantic coast, and over the greater portion of
this vast area of distribution, which is continued westward to the
Pacific, it forms the sole representative of the family. In the
south its habitat overlaps the range of the wood-hare (L. sylvati-
cus), which, in its several varietal forms, is distributed along the
Atlantic coast from Southern New England to Yucatan. West-
ward, the range of this species extends quite, or very nearly, to the
Pacific, keeping, however, to a course south of the isotherm of
45° F. The prairie-hare (L. campestris) is found in the interior
region, principally between the isotherms of 56° and 36°, its range
being consequently overlapped on the north by that of Lepus
Americanus, and on the south by L. sylvaticus. In the South-
eastern United States there are two distinct ‘species, L. palustris
and L. aquaticus, which are almost exclusively confined to the
marshy lowlands, and whose habitats, extending to Yucatan on
the south, are partially comprised in those of the wood-hare and
jackass-hare (L. callotis), the last a western species, whose range
descends into the arid interior of the Republic of Mexico. Finally,
we have a solitary species of South American hare (L. Brasiliensis),
whose reputed range embraces a considerable portion of the con-
tinent from Patagonia to Panama, continuing thence into Central
America.®

It frequently happens that the boundaries of a given species are
sharply defined against those of another, stopping just where the
others begin, and where, consequently, no overlapping takes place.
Such cases of specific limitation occur where natural obstacles to a
free migration are suddenly encountered, as where mountain or

24 GEOGRAPHICAL DISTRIBUTION.

water barriers project themselves into a given region. Thus, it will
not rarely be found that a genus of animals is represented by one or
several species on one side of a long mountain-slope, and by entirely
distinct species on the other. And, similarly, distinct species of a
genus may be encountered on opposite sides of a river-bed, although
instances of such a nature among the higher animals are probably
not of very frequent occurrence. Mr. Wallace cites the case of cer-
tain species of Saki monkey (Pithecia), found on either side of the
Amazon River, whose range either southward or northward appears
to be limited by that stream. 'The same naturalist instances among
birds species of jacamar (Galbula) and trumpeter (Psophia) which
exhibit a similar limitation, particularly the latter, where five dis-
tinct species are relegated to as many distinct, but contiguous, geo-
graphical areas, separated from each other by the Amazon and some
of its tributaries (Negro, Madeira, Tocantins). Of about twelve
species of armadillo (separated by some naturalists into several dis-
tinct genera), most of which are inhabitants of Brazil, it would
seem that not a single species is common to Brazil and the Argen-
tine Republic, or the Argentine Republic and Paraguay, the Parana
River, with its tributaries, evidently forming an insurmountable
barrier to the passage of this animal. The Uruguay River appears
in the same way to limit the eastward progression of the viscacha
(Lagostomys trichodactylus), an animal allied to the chinchilla,
although, as has been pointed out by Mr. Darwin, the trans-Uru-
guayan plains are fully as well adapted to the animal as those of
its native home.

Just as the boundaries of land-animals are in many instances
defined by the dominant river-courses, so, in a like manner, but in
a much more marked degree, the domains of fresh-water forms are
frequently circumscribed by the land surfaces bordering the waters
inhabited by them. This fact is beautifully exemplified in the geo-
graphical distribution of two American families of fluviatile mol-
lusks, the Strepomatid, or American melanians, and the Unionide,
the fresh-water mussels, where the species of several genera, at
least in the Southern United States, are restricted in their habitats
to certain individual streams, to the exclusion of all others. In-
deed, it would appear that even in such aquatic forms a large river
may constitute an almost insuperable barrier to migration, as is
shown in the case of the Strepomatide by the Mississippi (south of

DISTRIBUTION OF JAYS. 20

the line of the Ohio River), which but very few members of the
family have been able to surmount. According to Tryon, only one
species of the family, Goniobasis sordida, is positively known to be
common to the region on both sides of that great stream.°
Probably no group of animals, as Mr. Wallace well observes,
illustrates in a more striking manner the extreme features of specific
distribution than the true jays, birds of the genus Garrulus. About
fourteen species are recognised by ornithologists, whose combined
domain embraces the entire east and west extent of the continent of
Eurasia, from the Bay of Biscay to the Sea of Okhotsk, and also in-
cludes the continental British Isles on the west, and the Japanese
group on the east. Most of these species occupy independent areas
of their own, or areas which but barely overlap on their contiguous
borders. Thus, the common jay (Garrulus glandarius) inhabits the
greater portion of the semi-continent of Europe, ranging from the
Barbary States in Africa northward to about the sixty-fourth paral-
lel of latitude (in Scandinavia and Russia), and east to the Ural
Mountains. Along its southern border it meets the Algerian jay (G.
cervicalis), a distinctly-marked species, and one having but a very
limited range. On the southeast, again, its confines meet those of
the black-headed jay (G. Krynicki), which occupies a somewhat cir-
cular district extending some distance on all sides of the Black Sea.
Contiguous with this last is the region inhabited by the Syrian jay
(G. atricapillus), a species very closely allied to the preceding,
whose domain extends through Syria, Palestine, and Southern
Persia. North of this we have the limited area occupied by the
Persian jay (G. hyrcanus), which has thus far been found only on
the Elbruz Mountains. In an almost direct line east of this region,
but separated from it by a considerable area where no jays are to be
met with, we pass consecutively over the haunts of the black-
throated jay (G. lanceolatus), from the Northwestern Himalayas, the
Himalayan jay (G. bispecularis), from the Himalaya Mountains to
the eastward of Cashmere, the Chinese jay (G. Sinensis), from South
and Central China (and, occasionally, Japan), and the Formosan jay
(G. Taivanus). The home of the Burmese jay (G. leucotis) adjoins
that of the Himalayan jay on the southeast. North of the belt
occupied by the species of southern jay we have a vast region
—the desert area of Central Asia, with Thibet, Turkestan, Mon-
golia, and Gobi—throughout the greater part of which no jays

26 GEOGRAPHICAL DISTRIBUTION.

have as yet been discovered. Bounding this area on the north, and
extending from beyond the Ural Mountains (Kazan) to the northern
island of the Japanese group, there exists an almost continuous and
comparatively broad belt which is tenanted throughout its entire
extent, except where it overlaps the habitat of the common Euro-
pean G. glandarius, by a solitary species, known as Brandt’s jay (G.
Brandti). Finally, in the southern island of Japan there are found
two species, G. Japonicus and G. Lidthi, the former of which, sin-
gularly enough, is the species which is most nearly allied to the
common European jay, although separated by the greatest distance
from it.”

Generic Distribution.—The laws governing specific distribu-
tion are in considerable measure likewise applicable to the dis-
tribution of genera. Thus, we have genera that are restricted to
very limited areas, and, as a necessary consequence resulting from
specific distribution, those whose areas are coextensive with con-
tinental boundaries, or embrace portions of two or more continents;
and, again, we have genera of a given family which occupy con-
tiguous, overlapping, or discontinuous provinces. The localisation
of a genus to an exceptionally narrowly circumscribed area, such
as we have scen in the case of the species of humming-birds of
the volcanic peaks of South America, can almost necessarily ob-
tain only there where the number of species belonging to the
genus is also exceptionally limited, or, more nearly, when the
genus is coextensive with a single species. Potamogale, which
comprises the single species P. velox, a singular otter-like insecti-
vore of the west coast of Africa, appears to be confined to the
region included between Angola and the Gaboon ; Cheeropsis,
with the single species C. Liberiensis, an animal closely allied to
the true hippopotamus, inhabits, as far as is yet known, only the
wilds of Liberia; and, likewise, the singular carnivore constituting
the genus Ailurus (A. fulgens) has been met with only in the
Southeastern Himalayas. Instances of restriction are much more nu-
merously presented in the case of insular than of continental faunas,
‘whether the examples be taken from the class of birds or mam-
mals.

Genera of very broad, or almost world-wide distribution, are of
frequent occurrence, both among the lower and higher animals.
Among the latter, in the class of birds, we have numerous examples

GENERIC DISTRIBUTION. Par

among the swimmers, waders, and birds of prey, whose range
covers the greater extent of the primary divisions of the earth’s
surface, and which may, consequently, be said to have a cosmo-
politan distribution. Generic groups with a nearly world-wide
distribution among the Mammalia are of much rarer, although of
not exactly infrequent, occurrence, and if the Australian dingo,
a species of wild dog, be not considered indigenous to the country
which it inhabits, there would appear to be, if we except the bats,
not a single altogether cosmopolitan genus among that class of ani-
mals. Leaving out of consideration the continent of Australia,
whose mammalian fauna is deficient in nearly all the orders of the
class, we have a considerable number of genera whose range com-
prises the greater portion of the habitable globe.* Thus, the mem-
bers of the genus Felis (cats) are spread throughout the entire
expanse of the continents of both the Eastern and the Western
Hemisphere, through regions the extremes of whose temperature
may be measured by probably no less than 225 degrees of the
Fahrenheit scale. The genus Canis (dogs) has an almost equally
broad distribution ; and the same range is exemplified in the case
of the weasel genus (Mustela). Ursus, the bear, is met with
throughout the greater part of the Northern Hemisphere, and in
the continent of South America the genus has one or more rep-
resentatives whose habitat is situated considerably to the south of
the Equator.t The genus Cervus (deer), in its broader sense, has
representatives in both North and South America, Europe, and
Asia, with a very limited number of species (fallow-deer, stag) in
Africa north of the Sahara.

Discontinuous generic areas, like specific areas, are of com-
paratively rare occurrence. Among the most remarkable instances
of such discontinuity we have that exhibited in the case of the

* The only placental animals indigenous to the Australian continent, if we
exclude the rather doubtful dingo, which is by most naturalists considered to
have been introduced by man, are the Cheiroptera (bats) and Rodentia, the
latter represented by the family of mice (Muridw), The implacental mam-
mals—kangaroos, wombats, phalangers—have, on the other hand, an extraor-
dinary development.

+ The solitary species of bear inhabiting the continent of Africa appears to
be confined to the Atlas Mountains; it constitutes the genus Helarctos of
some authors (H. Crowtheri).

28 GEOGRAPHICAL DISTRIBUTION.

genus Myogale, the water-mole, already referred to, which em-
braces two species, one of which, M. Pyrenaica, is an inhabitant of
the northern valleys of the Pyrenean chain of mountains, and the
other, M. Muscovita, the plains of Southeastern Russia skirting the
Don and Volga rivers. The pikas (Lagomys), small rodent animals
having a rather near relationship with the hares, which are exten-
sively distributed along the upper mountain heights from the Ural
to Cashmere and the eastern extremity of Siberia, have a single
outlier in the Rocky Mountains of North America. The members of
the genus Capra—the goats and ibexes—occupy disjointed patches
of territory in Europe, Asia, and Africa, mainly confined to the
elevated mountain regions, such as the Pyrenees, the Sierras of
Spain, the Alps, Caucasus, Himalayas, &c., the intervals between
which are deficient in the wild or indigenous representatives of the
genus. <A similar discontinuity is exhibited in the case of the
snow-partridges of the genus Tetraogallus, a bird likewise partial
to the elevated mountain-slopes. Numerous other instances of
birds occupying discontinuous areas may be cited, and they appear
particularly noticeable among families of a more or less tropical
habit. Such, for example, are the jaganas (Parra), which inhabit
the tropical regions of both the Old and the New World, the simi-
larly distributed flamingoes (Phcenicopterus), the wood-ibises of
the genus Tantalus, the gerontics (Geronticus), and the marabou
storks (Mycteria). Among perching birds a most remarkable in-
stance of generic discontinuity has been cited by Wallace in the case
of the blue magpies (Cyanopica), which comprise two species, one of
which, C. Cookei, inhabits the Spanish Peninsula, and the other, C.
cyanus, Eastern Siberia, Japan, and North China, the habitats of
the two being removed from each other by an interval of fully 5,000
miles. Still more marked is the case of the bluebirds constituting
the genus Sialia, all of whose members, with one exception, inhabit
temperate and tropical America; a solitary form, Sialia (Grandala)
ceelicolor, singularly enough, crops up again among the Himalaya
Mountains, and eastward throughout the mountainous region sepa-
rating China from Thibet.° The most remarkable instance of a
mammalian genus occupying two widely -removed areas is fur-
nished by Tapirus, the tapir, several species of which are natives
of the South American continent, and one, very distinct from the
others, of Malacca and Borneo, the group of animals, therefore,

DISTRIBUTION OF FAMILIES. 29

appearing at localities separated from each other by nearly half of
the earth’s circumference.

Distribution of Families.—The restriction of families to cer-
tain local areas is of comparatively rare occurrence, an almost neces-
sary consequence of the number of species and genera of which they
are in most cases composed. Among mammals the Cheiromydz,
with one genus and one species, the aye-aye (Cheiromys Madagas-
cariensis), are confined exclusively to the Island of Madagascar; the
Protelide, likewise consisting of but a single genus and species, the
aard-wolf (Proteles Lalandii), an animal in several respects inter-
mediate between the cats and dogs, and considered by some as
representing a greatly modified form of hyena, are confined to the
extra-tropical regions of South Africa. Occupying pretty nearly
the same region, and confined to it, are the Chrysochloride, or
golden-moles, with a single genus and about five species. The
Ailuride, a group of animals having their nearest allies in the
coatis and bears, and consisting of one or two species, appear to
be restricted to the forest region of Eastern Thibet and the Eastern
Himalaya. Among the class Aves we have likewise families that are
restricted both as to the number of species comprised by them and
the region which they inhabit. The Paictide, a group of birds,
considered by some ornithologists to have affinities with the Ameri-
can ant-thrushes (Formicariidie), and by others with the Old-World
pittas, consist of a single genus and two or more species, both of
which are confined to the Island of Madagascar. Here, also, ex-
clusively belong the Leptosomide, birds allied to the cuckoos and
rollers. The Apterygide, with one genus (A pteryx) and four species,
are strictly confined to the two larger islands of New Zealand; the
Drepanidz, with some four or five genera and ten species, are re-
stricted to the Sandwich Island group; and, finally, the paradise-
birds, excluding the bower-birds, which are classed together with
them in one family by some ornithologists, with about eighteen
genera and thirty species,“ are almost entirely confined to New
Guinea and the surrounding islands, only four representatives of the
group finding their way into the neighbouring continent of Australia.
Mr. Wallace has emphasised the very remarkable case of localisation
presented among reptiles by the Uropeltidx, or rough-bellied, bur-
rowing snakes, all of whose members appear to be strictly con-
fined to Ceylon and the adjacent parts of the Peninsula of India.°

30 GEOGRAPHICAL DISTRIBUTION.

Families with restricted ranges, like genera and species, are of
infrequent occurrence, broad distribution being with them the rule
rather than the exception. Nevertheless, owing to the peculiarily
isolated position of the Australian fauna, there are among the land
Mammalia only two families which can lay claim to being strictly
cosmopolitan. These are the mice (Muridz) among rodents, and
the Vespertilionide among bats, the former being universally dis-
tributed throughout the globe, if we except some of the island
groups of Australasia. The Vespertilionide have representatives
almost everywhere, being apparently limited, as stated by Wal-
lace, only by the necessities of procuring insect food. Among
birds, examples of practically cosmopolitan families are presented
by the thrushes, warblers, crows, swallows, king-fishers, goatsuckers,
and pigeons. The hawks, owls, ducks, and gulls are cosmopolitan
par excellence, being found in almost every habitable locality
throughout the globe, whether on the mainland or on the most
distantly removed oceanic islands. The extensive family Fringil-
lide (finches, buntings), as now generally constituted by ornitholo-
gists, with upwards of seventy genera and five hundred species,
appears to have no representative in Australia, all the finch-like
birds of that continent belonging to the family of the weavers
(Ploceide).

As with genera and species, so likewise in the case of families,
we have numerous instances of groups occupying discontinuous
areas. In the class of Mammalia, for example, the swine (Suid),
which are so extensively distributed throughout both the tropical
and temperate regions of the Old World, have no representatives in
the New World north of about the thirty-fourth parallel of latitude
—the Red River, in Arkansas—although they have two species (of
peccary) in the region south of that line. The Orycteropodide
have a solitary representative in the Cape District, the aard-vark, or
Cape ant-eater (Orycteropus Capensis), and another in the interior of
Northeast Africa and in Senegal, the form occurring in the latter
region being possibly a third species.” The tapirs, constituting
the family Tapirid, have, as already stated, their representatives
on opposite sides of the globe, one species inhabiting the Malay
Peninsula and some of the adjacent islands, and the four or five
others the tropical forests of Central and South America, The
chevrotains, or deer-like animals of the family Tragulide, abound

DIVIDED FAMILIES. 31

in India and some of the islands of the Malay Archipelago, where
they constitute the genus Tragulus; a solitary representative of the
same family, but belonging to a distinct genus (Hyomoschus), is a
native of West Africa. The anthropoid apes (Simiide) are repre-
sented in Western (and probably also East Equatorial) Africa by
one or more species of gorilla and chimpanzee (Troglodytes), which
are almost exclusively confined to the forest region. The form most
nearly allied to these man-like apes, and belonging to the same
family, is the orang (Simia satyrus), which, as an inhabitant of the
islands of Sumatra and Borneo, is encountered after an interval of
not less than seventy degrees of longitude. Inhabiting the same
region, but with a northward extension to China, and westward to
Assam (south of the Brahmaputra River), we find the members of
the genus Hylobates, the gibbons. Probably the most striking
example of a divided family is furnished by the Camelide, which
in the Old World are represented by the genus Camelus, with two
species—the dromedary and the Bactrian camel—whose habitat
extends from the Sahara through the desert regions of Western and
Central Asia to Lake Baikal; and in the New World by the genus
Auchenia (the llama, alpaca, vicufia, and guanaco), with about four
species, all of them restricted to the mountainous and desert regions
of Western and Southern South America. We have here, therefore,
a family which is not only divided by a vast ocean and the greater
mass of two continents, but the members of which, in one hemi-
sphere, inhabit the region north of the Equator, and, in the other,
the region south of it.

Instances of divided families among birds occur as in mammals,
although probably to a less marked extent, owing naturally to their
increased facilities for dispersion; such division obtains more espe-
cially among the so-called ‘‘tropicopolitan” forms, or those whose
homes are properly the region of the tropics, or that immediately
adjoining it. The flamingoes (Phenicopteride), consisting of a
solitary genus and about eight species, are about equally distrib-
uted as to the number of species throughout the warmer regions
of America, Africa, and Asia, some of the forms extending their
range to a considerable distance within the bounds of the Tem-
perate Zone, as in Southern Europe and South America. The
trogons (Trogonid), comprising many of the most beautifully-
arrayed of birds, and with upwards of forty species, are more

32 GEOGRAPHICAL DISTRIBUTION.

strictly confined to the tropical regions of the earth’s surface, but
few forms being found beyond the limits of that zone. They are
fairly abundant in the forest region of South America, ranging
from Paraguay to Mexico, and less so in South and Southeast
Asia, and some of the islands of the Malay Archipelago. In Af-
rica the family is represented by but two species. The Psitta-
cide among parrots furnish us with another good example of a
divided family, whose members are to be found only in the two
great southern continents, Africa and South America, and in some
of the adjacent islands. Still more remarkable is the case of the
ostriches, of which there are two species (of the genus Struthio)
pertaining to the desert regions of Africa and Western Asia (Arabia
and Syria), and likewise two (of the genus Rhea, sometimes placed
in a distinct family) belonging to temperate South America, whose
range extends from Patagonia to the confines of Brazil.

Among reptiles similar instances are presented by the tropi-
copolitan groups. Thus, we have the Crocodilide inhabiting the
tropical waters of both the Eastern and Western Hemispheres. The
Pythonide, or giant constricting serpents —boas, anacondas, pythons
—are, with the exception of the Californian genus Charina, some-
times referred to this family, distinctively tropical, but they have
representatives in the South American continent, in Africa, Asia,
Australia, and in several of the continental and oceanic islands.
The family of iguanas (Iguanide), comprising upwards of fifty gen-
era and some three hundred species, is almost distinctively Ameri-
can, being distributed from about the fiftieth parallel of south
latitude, in Patagonia, to the Canadian boundary-line on the north.
No member of the family is known from either of the continents
of Eurasia or Africa, yet the family crops up again in a solitary
genus—Brachylophus—in the Feejee Islands, and two (doubtfully
placed) genera have also been described from Madagascar and Aus-
tralia.

Distribution of Orders,—The principal features of geographical
distribution exhibited by species, genera, and families repeat them-
selves in a measure in the case of the higher groups of the animal
kingdom known as orders. Very narrowly circumscribed areas of
habitation, at least among the orders of higher animals, do not
exist; broad distribution is the rule. Among mammals the most
marked instances of semi-localisation, if so it may be termed, are

DISTRIBUTION OF ORDERS. ag

furnished by the Monotremata, comprising the two families of
duck-bills and echidnas, both restricted to Australia and the Isl-
and of Tasmania, and the Hyracoidea, an order consisting of two
genera, Hyrax (the coney) and Dendrohyrax, and about a dozen
species, all of which are restricted to the continent of Africa and
the immediately adjoining parts of Asia (Syria). The only orders
of terrestrial mammals which can lay claim to being cosmopolitan
are the Cheiroptera (bats) and Rodentia, none of the other orders,
except the Marsupialia—unless the dingo, as a member of the Car-
nivora, be considered indigenous to the continent it now inhabits
—having any representatives in Australia. Among birds we have
no instance of an order being restricted to the limits of a single con-
tinent. Among reptiles the Crocodilia are almost entirely confined
to the tropical and sub-tropical regions, and occur in both the East-
ern and Western Hemispheres. The Ophidia (serpents) have what
might be called a world-wide extension, although no member of
the order has been met with farther to the north than the Arctic
Circle. The order Anura (frogs and toads) among amphibians is
very nearly cosmopolitan ; the Urodela, on the other hand, com-
prising the tailed forms, such as the newts, salamanders, &c., are
almost strictly confined to the Northern Hemisphere, a few only of
its representatives passing through Central America as far south as
Colombia. The entire class of the Amphibia (as indigenous forms)
is absent from the vast majority of oceanic islands—New Zealand,
New Caledonia, and the Andaman Islands, and possibly the Solo-
mon and Seychelles groups, almost alone, according to Darwin,
presenting exceptional instances.

The marsupials afford a remarkable example of a comparatively”
large order of animals occupying widely separated and discon-
tinuous areas. With the exception of the opossums, of which
there are two genera and about twenty species, confined to the
two continents of America, and more particularly to the tropi-
cal regions of these continents, all the members of this peculiar
and lowly-organized order of animals are strictly limited in their
range to the Australian continent and its dependent islands, and
some of the islands of the Malay Archipelago. In all the broad
intervening region—Europe, Africa, and Asia—no representative of
the order is to be met with. The Edentata—ant-eaters, armadillos,
&c.—are largely confined to the tropical and sub-tropical regions

34 GEOGRAPHICAL DISTRIBUTION.

of South America, Asia, and Africa, and are almost completely
absent from the vast northern tracts which spread out towards the
polar confines, and tend to bring together the terrestrial areas of the
Old and the New World. The order is entirely wanting in Europe,
and nearly so in North America, the genus Tatusia, an armadillo,
alone penetrating within the boundaries of the last into the State
of ‘Texas. In Asia no member of the order is found to the north
of the Himalaya Mountains. A remarkable example of discon-
tinuous habitation among birds is furnished by the Struthiones, or
ostrich-like birds, whose members are distributed throughout con-
siderable reaches of tropical and sub-tropical South America, Africa,
Asia, and Australia, some of the Australian islands, and New Zea-
land, and are entirely wanting in Europe and North America. It
is a singular circumstance in connection with the distribution of
the birds of this very limited order that two genera, so closely
allied as are Rhea and Struthio, should occupy areas so distantly
removed from each other as Africa and South America. The
Psittaci, or parrots, inhabitants of both the New and the Old
World, may likewise be considered as being preeminently tropical
and sub-tropical, for although a few examples are found whose
range in the Southern Hemisphere ascends to the fifty-fourth degree,
yet the true home of the order is located in the zone embraced be-
tween the thirty-fifth parallels north and south of the Equator.
Being absent from Europe and the greater portion of the continent
of North America, the distribution of the order is necessarily dis-
continuous.

Mn gy

Conditions affecting distribution.—Climate.—Food-supply.—Barriers to mi-
gration.—Migrations of mammals and birds.—Dispersal of insects and
mollusks.

Of the Conditions which affect or limit Distribution among
Animals.—Climate.—It is a common belief that the principal fac-
tor limiting or regulating the distribution of animals is constituted
by climate; in other words, certain groups of animals are associated
with certain grades or conditions of climate, beyond the reach of
whose interacting influence they could no longer maintain an exist-
ence. Thus, among quadrupeds, the elephant, camel, and tiger are
popularly associated with the hottest climates of the earth’s surface;
the reindeer and moose with climates of equal, but opposite, sever-
ity. And, similarly, among birds, the ostriches and hummers are
considered to be particularly indicative of hot or tropical climates,
and the auks, guillemots, puffins, and penguins, as products of the
cold northern or southern climes. That climate does regulate dis-
tribution, or impose a bar upon the migration of certain forms of
life, there can be no manner of doubt; but that it does not exercise
the paramount influence that is generally attributed to it there can
likewise be no question. Taking, for example, some of the in-
stances that have just been mentioned as indicating the supposed
association between animal distribution and given conditions of
climate, we find that the tiger, while its home, par excellence, may
be considered to be the hot districts of India and the Indian Archi-
pelago, is in no way restricted in its range to those regions, or to
regions having at all a similar climate. Thus, the animal is found
in the elevated regions of the Caucasus and the Altai chain, and in
the Himalaya range its footprints are not infrequently found im-
pressed in the fields of snow. It is a permanent inhabitant of the

36 GEOGRAPHICAL DISTRIBUTION.

cold plains of Manchuria and the Amoor region, as well as of the
plains lying north of the Hindu-Kush, in Bokhara, prowling about
even in winter along the icy margins of the Aral Sea. As a matter
of fact, the range of the tiger extends to about the fifty-third paral-
lel of north latitude—or what corresponds to the position of Lake
Winnipeg, in British America—in the neighbourhood of Irkutsk and
Lake Baikal. Nor can this northern range be taken to represent
the range of simply stray individuals, since in the region of South-
east Siberia traversed by Radde that traveller affirms that tigers
were uncommonly abundant.”

Although at the present time the lion is confined almost exclu-
sively to the tropical and sub-tropical regions of Africa and Asia,
there can be but little doubt, as appears from the writings of Herod-
otus and Aristotle, that as late as the beginning of the historic
period that animal still inhabited in Europe a region lying as far
north as about the fortieth parallel of latitude— or what corre-
sponds in position to the State of Pennsylvania—namely, the region
of Thessaly, in Greece. And even at the present day the Tunisian
lion is occasionally found in the neighbourhood of the thirty-seventh
parallel of north latitude, and until recently the Cape lion was
abundant in or about the district of the Cape, extending to the
thirty-fifth parallel of south latitude. Although the climate of
these latitudes in Africa is of an unusually mild character, yet there
are sudden changes of temperature, as between day and night,
which may be likened to the changes in the temperature between
the summer and winter climates of more temperate regions. We
are informed by travellers that in the Kalahari Desert and other dry
open districts of South Africa the nights are frequently unpleasant-
ly cool, or even cold, the free and rapid radiation of heat from the
soil not rarely being accompanied by a freezing of the surface. The
formation of ice in the Desert of Sahara is, likewise, not exactly of
exceptional occurrence, but in that region of the African continent,
except on its immediate borders, lions are only rarely met with.

That a restriction to warm climates is likewise not the case with
the elephant is almost conclusively proved by the readiness with
which, in the Roman period, these animals were made to pass the
barrier offered by the lofty Alpine chain. Still more indisputable
evidence on this point is, however, afforded by the habits of the
Indian elephant, which appears to be equally at home among the

CLIMATIC INFLUENCES. 37

cool mountain heights as amidst the hot and jungly lowlands. In
Ceylon, according to Sir Emerson Tennent, ‘‘the mountain-tops,
and not the sultry valleys, are his favorite resort. In Oovah, where
the elevated plains are often crisp with the morning frost, and on
Pedro-Tella-Galla, at the height of upwards of eight thousand feet,
they are found in herds, whilst the hunter may search for them
without success in the jungles of the low country. No altitude, in
fact, seems too lofty or too chill for the elephant, provided it affords
the luxury of water in abundance; and, contrary to the general
opinion that the elephant delights in sunshine, he seems at all times
impatient of its glare, and spends the day in the thickest depths of
the forest, devoting the night to excursions, and to the luxury of
the bath, in which he also indulges occasionally by day.” '* | Mr.
Johnston, during his recent explorations of the Kilimanjaro region,
encountered elephants, together with buffaloes, and one or more spe-
cies of antelope (kudu), at an elevation of thirteen thousand feet.***
The camel is an animal popularly associated with the burning
desert regions of Africa and Asia, yet the two-humped or Bactrian
species is found throughout the greater portion of Mongolia and
Chinese Tartary, in the mountain region as well as in the lowlands,
lying between the fortieth and fiftieth parallels of latitude, and it
extends its range even considerably beyond the fiftieth parallel into
Siberia, as along the borders of Lake Baikal, where it appears to
pass the winter season without discomfort. It is a fact worthy of
note that the only other existing representatives of the camel family
—the llama and llama-like animals of the New World—are strictly
adapted to a rigourous winter climate, as is shown by their partiality
to the highly-elevated tracts of the South American Andes. The
same adaptability to different extremes of climate likewise presents
itself in the case of many of the so-called Arctic animals. The
reindeer, while it habitually prefers for its home a region that en-
joys a more or less rigourous climate, and where the soil is for the
greater part of the year covered with snow, does not appear to be
impatient of the summer heat of comparatively low latitudes, as is
proved by the circumstance that in the various zoological gardens
of Central Europe it not only develops in good condition, but also
breeds freely. Indeed, its restriction to the high northern latitudes
appears to be in no way dependent on considerations connected
with either cold or snow, but merely upon the presence there in the

38 GEOGRAPHICAL DISTRIBUTION.

greatest abundance of its particular food, the reindeer-moss and
various lichens, without which it seems incapable of flourishing.
There can be little doubt that were individuals of the reindeer
transplanted to an elevated mountain region, such as the European
Alps, for example, where their own proper nourishment would be
again met with, they would thrive very nearly, if not fully, as well
as in their true homes north of the fifty-fifth or sixtieth parallel of
latitude. Indeed, even in their northern haunts the animals, at
least as is shown by the American species or variety, would seem to
be impatient of too great a cold, since in the winter they seek the
inner recesses of the forests for protection.

Turning row to the class of birds, we find that similar illustra-
tions of climatic adaptation present themselves. Thus, the usually
considered ‘‘ tropical” or *‘ equatorial” hamming-birds are in reality
not such at all. While it is true that by far the greater number of
species belonging to this family are found within the region em-
braced within the tropics, yet the range of the family extends all
the way from Cape Horn (Eustephanus galeritus) to Sitka (Selas-
phorus rufus), or over a territory covered by no less than one hun-
dred and fifteen degrees of latitude. And even among the strictly
tropical forms many of them extend their range to the limits of
perpetual snow, some remaining in the cold region permanently.
The Oreotrochilus Chimborazo and O. Pichincha have their abode
in the equatorial peaks indicated by their respective specific names
at an elevation of no less than sixteen thousand feet—or higher than
the summit of the Mont Blanc—in a world of almost perpetual
snow, hail, and sleet.* In fact, the elevated Andean slopes are
much more thickly visited by humming-birds than the deep low-
lands, no matter how luxuriantly these last may be clothed with
vegetation.

The ostriches constitute another group of animals whose habitat
is popularly associated with the burning deserts of the Torrid zone.
While it is unquestionable that these birds do delight in just such
districts, it may yet be doubted whether the matter of climate has
very much to do with the selection of a region, since ostriches are,
or have been until recently, equally abundant in all parts of the
African continent, in the high table-lands as well as in the low-
lands, from Algeria to the Cape, and from the east to the west
coast, where the suitable desert conditions present themselves, and

CLIMATIC INFLUENCES. 39

where, consequently, as has already been stated, the differences
between the temperature of night and day are excessively marked.
In the desert region of Western Asia—Persia and the Valley of the
Euphrates—the bird ranges or ranged as far north as about the
thirty-fifth parallel of latitude, and, indeed, it is not exactly im-
probable, as has been maintained by Vambéry,* that even at the
present day it exists in limited numbers along the shores of the
Sea of Aral, in about the forty-fifth parallel, or what would cor-
respond to the position of the southern portion of the State of
Maine. In the case of this family—Struthionide—we also notice
the singular fact, analogous to that which has been observed in
relation to the distribution of the Camelide, that the only repre-
sentatives of the group other than Struthio (the ostrich proper),
constituting the American genus Rhea, are birds belonging almost
strictly to the temperate regions, their range extending from Pata-
gonia to the southern confines of Brazil. The parrots (Psittaci)
may be considered to be preeminently tropical birds, the vast ma-
jority of the species being included in a zone bounded by the
thirtieth parallel on each side of the Equator, but yet it may be
doubted whether this limitation does not depend more upon the
nature of the food-supply than upon the character of the climate.
In South America a species of Conurus extends its range as far as
the Strait of Magellan, and in the Macquarie Islands, in the South
Pacific, representatives of the family are met with as high as the
fifty-fourth parallel of latitude, corresponding to a position removed
by only six degrees from the southern extremity of Greenland.
Wallace probably justly refers to the ‘‘almost universal distribu-
tion of parrots wherever the climate is sufficiently mild or uniform
to furnish them with a perennial supply of food.” ®

But while in numerous, and perhaps the majority of, instances the
limitation of animal groups to certain geographical regions is de-
pendent more upon the physical character of the immediate environ-
ment and the nature of the food-supply than upon particular con-
ditions of climate, yet it cannot be denied that in very many cases
climate appears to exercise a paramount influence upon distribution.
This influence is frequently considered to be nowhere more forcibly
illustrated than in the migration of birds, both as regards the
northern species and those inhabiting the southern climes. That
the climatic explanation of the phenomenon of bird migration is a

40 GEOGRAPHICAL DISTRIBUTION.

fallacy most ornithologists are now agreed. It is a well-ascer-
tained fact that the vast majority of birds are migrants to a greater
or less degree, and that non-migration with this class of animals
is much more of an exception than the rule. Yet, by reason of
their peculiar covering, birds generally, as compared with other
vertebrates, are but slightly affected by extremes of either heat or
cold, and indeed, as far as we are capable of judging, by most
climatic influences, provided only that their food-supply is not
affected thereby. The condor in its aerial flight within a few
minutes of time accommodates itself to the most varying climatic
conditions, the change from the freezing cold of the mountain
heights to the scorching heat of the tropical lowland plains seem-
ingly having no effect upon the vigour of the bird. There can be
but little doubt, as has been insisted upon by Professor Newton,
that a deficiency in the food-supply—the necessity for searching
for new food—is the most obvious cause or impulse promoting
bird migration. Migrations of a somewhat similar character, in-
disputably governed, at least in part, by considerations connected
with the food-supply, but also in greater part by conditions of
climate, manifest themselves among several other classes of ani-
mals. Thus, in India, the monkeys habitually ascend the Himalaya
Mountains in summer to elevations of ten or twelve thousand feet,
and again descend in winter. Semnopithecus schistaceus has been
observed at a height of eleven thousand feet, leaping in fir-trees
laden with snow wreaths! Wolves in severely cold weather descend
from the mountain-slopes to the lowlands, and bears not infrequently
migrate in great numbers to escape the rigours of an extreme winter.
The migratory instincts of the northern hares and squirrels, and
more particularly of the Norway rat and lemming, which in severe
winters move in amazing numbers in direct lines over lake, river,
and mountain, overcoming all obstacles that might be placed in
their path, are well known. The Kamtchatka rats, under the
pressure of numbers, are stated by Pennant to travel westward for
a distance of eight hundred miles or more. Similar instances of
the force of migration are presented by the hoofed animals. The
vast herds of moving buffalo were until recently familiar sights to
the traveller on the American plains ; in South Africa countless
numbers of antelope, impelled by the necessities of food-supply,
pour down upon the more favoured districts lying without the

ANIMAL MIGRATIONS. 41

region of parched soils; and similar excursions, although in this
case governed by reversed thermometric conditions, are practised
by the onager or wild ass of Tartary. Even the reindeer is to an
extent a migrant, since in both Russia and Chinese Tartary it de-
scends far southward in advance of a rigourous winter, and, indeed,
frequently reaches a lower latitude than any part of England, al-
though in Scandinavia the animal is rarely seen south of the sixty-
fifth parallel.

It is not alone among the higher animals that the migratory in-
stinct is developed. Turtles, during the ovipositing season, move
in considerable numbers from one part of the sea to another, and
they are stated to find their way annually to the Island of Ascen-
sion, which is distant upwards of eight hundred miles from the
nearest continental land-mass.** Fishes migrate in immense num-
bers, but the periodical shifting of the abodes of these animals is
directly connected with the processes of reproduction. Certain
fishes, as the salmon, shad, and smelt, ascend the waters of fresh-
water streams for the purpose of depositing their eggs; others,
again, as the herring and mackerel, frequent in immense shoals,
during the breeding season, the neighbourhood of the coast-line.
The young eel follows the line of the river-courses in myriads,
ascending all the tributary streams, and frequently overcoming
apparently impassable water - falls by squirming over the moss-
covered ledges on either side. Among insects, the devastating
migrations of the locust are proverbial, and similar illustrations of
the wandering instinct could be cited from other members of the
same class of animals. A remarkable example of migration has re-
cently been observed in the case of a species of grapsoid crab (Se-
sarma ?) off Cape San Antonio, the western extremity of the Island
of Cuba.

Barriers to Migration, and Facilities for Dispersion.—It
has already been remarked that the interposition of extensive and
elevated mountain-chains and of large bodies of water, and also
sudden changes in the physical character of a country, are insur-
mountable obstacles in the way of the migration or dispersion of
certain classes of animals. The most serious of these obstacles, as
affecting the dispersion of the Mammalia, is of course that of large
bodies of water. We are well aware that the most experienced
swimmer among this class of animals can accomplish by the nata-

42 GEOGRAPHICAL DISTRIBUTION.

torial process but an insignificant journey, and, therefore, it would
necessitate the interposition of but a very moderate expanse of
water to effectually bar its progress in any given direction, Several
members of the cat family are expert swimmers, the jaguar being
known to cross the broadest of the South American rivers, the La
Plata, as observed by Lieutenant Page. The tiger and elephant are
both good swimmers. Deer are likewise prone to take to water,
but it may be questioned whether animals of this kind would be
apt to trust themselves beyond the sight of land. The domestic
pig, even at a very young age, has been known to swim five or six
miles, and it is not exactly impossible that the wild-hog, in cases of
absolute necessity, might successfully attempt a passage of three or
four times this distance. Probably the most remarkable exhibition
of the natatorial powers of a land animal is that shown in the case
of a polar bear, which was observed by Captain Parry vigourously
paddling away in Barrow’s Strait at a nearest distance of twenty miles
from the shore, with no ice in sight on which it could have secured
needed repose. It may safely be conceded, from our present knowl-
edge on the subject, that while many of the land Mammalia can
effect with safety, and even readiness, such water passages as are
most gencrally to be met with on continental areas, none, probably,
would be prompted to undertake a journey across an arm of the sea
whose width measured fifty or more miles, or even one much ex-
ceeding half that extent.* To these difficulties or impossibilities
in the way of dispersion must be attributed the circumstance that
the vast number of oceanic islands are deficient, except where man
has effected an introduction, in representatives of this particular
class of animals. The fact that certain allied, or even identical,
forms of mammals are found in regions widely removed from each
other, and which at the present time are separated by impassable
bodies of water of greater or less extent, is practically conclusive evi-

{

* In the case of the polar bear above cited, the absence from view of any
ice need not necessarily, or even probably, indicate that there was no ice pres-
ent nearer to the swimming subject than the ice of the land-border. From the
mast of a vessel, elevated one hundred and fifty teet above the surface of the
water, an iceberg rising to the same height could not, owing to the curvature
of the earth, be distinguished at a greater distance than thirty-four miles ; flat
masses of pack-ice, rising but a few feet above the water, at only about half
that distance.

DISPERSAL OF MAMMALS. 43

dence that in the former periods of the earth’s history the surface of
the globe must have undergone such vicissitudes as to have at vari-
ous times disturbed the general relations existing between land and
water. In other words, much of the surface that at one time was
occupied by water must have been replaced by land, and, per contra,
what was at one time land must at another have been water. And
evidences of such variations in terrestrial equilibrium are abundantly
afforded by geological landmarks. Had the greater portion of the
surface of the globe at one time since the introduction of the Mam-
malia consisted principally of dry land, or had there been since
that period a general alternation in the relative positions of the land
and water areas, the geographical distribution of the Mammalia
would have been very different from what we actually find it to be.
Hence, it must be assumed that a land and water alternation, such
as could have brought about the present result, must have taken
place in certain parts of the earth’s surface only, and without affect-
ing others. There would seem to be very strong grounds for con-
cluding that the most recent connection uniting the principal land-
areas of the globe was formed in the Northern Hemisphere, asa belt
closing off the Arctic Sea (if it then existed) from the Pacific and
Atlantic oceans.

The only class of terrestrial mammals to which a broad arm
of water offers no impediment in the way of migration or disper-
sion is that of the bats; and, singularly enough, just in the case of
these animals, as has already been remarked, are we furnished with
an example of universal distribution, there being but very few of
the habitable oceanic islands which are not tenanted by one or more
representatives of the order. But even among the habitually ter-
restrial Mammalia there are certain exceptional methods by which
dispersion to very considerable distances from the mainland can be
effected. In the northern regions the frozen sea constitutes a con-
necting bridge between distantly-removed land-masses which is
constantly taken advantage of by various forms of Arctic animals.
By the breaking up and drifting away of fragments of the northern
ice-masses animals that might be temporarily wandering over them ~
could readily be transported to very considerable distances from
their true homes; and, indeed, it is through such means that polar
bears are periodically stranded upon the coast of Iceland. In one
year alone twelve of such wandering animals made their appearance

44 GEOGRAPHICAL DISTRIBUTION.

upon the island.” The reindeer is stated to cross the Behring
Straits by way of the Aleutian Islands and the frozen sea, and ina
somewhat similar manner the musk-ox finds its way to Melville
Island; it is, however, singular that the last named, despite its long
ice-journeys, never manages to reach either the continent of Asia or
Greenland. In regions like the tropics, which support a luxuriant
vegetable growth, and which are subject to periodical fluminal
overflows, and, consequently, to the uprooting or outwashing action
of the inundating waters, it not infrequently happens that islands
or ‘‘rafts” of considerable magnitude, consisting mainly of inter-
laced or matted vegetation—tree-trunks held together by various
creepers and climbers, and containing a sufficient quantity of vege-
table mould and soil bound together in the roots—are floated down
stream into the open sea, where they are at once placed at the mercy
of the prevailing oceanic and atmospheric currents. These rafts
have been frequently noticed at the mouths of some of the larger
streams, as the Mississippi, Amazon, and Ganges, and, in the case
of the last named, at a distance of a hundred miles from its mouth.
Floating masses of wood, with upright trees growing over them,
were mistaken by Admiral Smyth in the Philippine seas for true
islands, until their motion made their real nature apparent. Such
floating masses not rarely harbour various forms of animal life in
their midst, and among these the Mammalia with arboreal hab-
its are not inadequately represented. The South American tray-
ellers Spix and Martius assert that on different occasions they ob-
served monkeys, tiger-cats, squirrels, crocodiles, and a variety of
birds, carried down stream (the Amazon) in this manner, and simi-
lar observations have been made by other travellers in the case of
the Rio Parana. It is asserted that no less than four pumas were
landed in one night from such rafts in the town of Montevideo.*
Some of the animals thus conveyed may travel unconcernedly, and
without any special disadvantage arising from a change of abode;
others, as the larger quadrupeds, will have been caught up and
transported through accident. To what distance such a floating
raft with its living cargo may ultimately be carried in safety, and
without detriment to its inhabitants, over the oceanic surface there
are as yet no data for determining. But there would appear to be
no reason for assuming that they could not be transported to a
distance of several hundreds of miles, seeing that the upright vege-

DISPERSAL OF REPTILES. 45

tation found on many of them would serve with powerful effect in
the face of a wind. And while the majority of the animal inhab-
itants might be exterminated before the end of the voyage the safe
arrival on an island or distant shore of a very limited number of
individuals, embracing both males and females, would serve in a
short period, under favourable conditions, to stock the new land
with the species. That an absolute limit is set, however, to migra-
tion as effected in this manner is proved conclusively by the utter
absence in most of the oceanic islands of indigenous mammals, ex-
cepting bats.

The same obstacle that is interposed by the ocean to the disper-
sion of the Mammalia presents itself in the case of the vast majority
of other terrestrial animals in which the power of flight is not at all,
or at best but feebly, developed. Thus, the serpents, although many
of them are fairly good swimmers, are, if we except the marine
forms, as incapable of passing oceanic barriers as are the quadrupeds,
and their transportation from continental areas to regions far remote
can only be effected by such or similar accidental means as that
just described. As might have been expected, therefore, they are
absent from nearly all oceanic islands. The Amphibia (frogs and
toads) are no more fortunate in passing broad arms of the sea than
are the serpents, despite the circumstance that in their young or
larval condition they are strictly aquatic in their habits. Salt water
proves fatal both to them and their eggs. Since moisture is a
necessary condition for the early existence of this class of animals,
it is evident that an extensive desert region will be an effectual
barrier to their distribution—in fact, about as much so as an ocean.
Lizards, in their adult condition, are as incapable of traversing an
oceanic region as are the snakes and amphibians; but it would ap-
pear that in some special way—whether as effected by the oceanic
currents themselves or through the agency of birds—their eggs
may be transported to very considerable distances out to sea, since
this order of animals is sufficiently represented in remote islands
where neither snakes nor amphibians have as yet been encountered.
That the ocean offers no insuperable obstacle to the broad disper-
sion of a very large body of birds is known from almost daily
observation. Birds are known to pass several hundreds of miles
on the wing without halting, and, indeed, it is not exactly im-
possible, or even improbable, that such unassisted flight may ex-

46 GEOGRAPHICAL DISTRIBUTION.

tend over one or more thousands of miles. The flights of the
wild-goose and the swallow have been estimated to be performed
at the almost incredible velocity of from sixty to ninety miles per
hour, and the flights of many of the smaller birds at not very
much less. A sustained flight of ten or more hours in duration,
especially when assisted by a favourable wind, involving an amount
of muscular exertion probably within easy command of many birds,
would carry them over an enormous stretch of territory, during a
period of time which, by its brevity, would render the question of
food-supply comparatively unimportant. Land-birds have been en-
countered in the North Atlantic at almost all points of the oceanic
expanse; but to what extent these stragglers have received assist-
ance in their flight, by taking temporary shelter on board the nu-
merous vessels plying between Europe and America, can hardly be
determined. There is no question as to such assistance in numerous
instances, but whether it is afforded in all or most cases is a matter
of pure conjecture. By whatever means or methods the oceanic
travel of birds may be effected, it is a matter placed beyond all ques-
tion that numerous American birds make their appearance at inter-
vals along the European coast. Upwards of sixty species of such
foreigners, embracing examples from nearly all the orders of birds,
have at different times been noted on the eastern coast of the At-
lantic, principally in the British Isles and the Island of Heligoland.”
Singularly enough, no distinctively European birds make their ap-
pearance on the American coast, except a few whose journey over
is made by way of Greenland and Iceland.* Despite the long-
sustained flight of which birds are capable, it may be considered
exceedingly doubtful whether many or any of them undertake
these protracted journeys as a matter of their own pure choice or
volition. It seems hardly possible that an animal would subject
itself to such an amount of exertion and privation as would appear
to be involved in journeys of this length, when no material ad-
vantage could in the end be derived therefrom. It therefore ap-
pears more than probable, as has been urged by Baird, Wallace,

* No account is here taken of the purely pelagic forms, which are found
on the opposite borders of the oceanic expanse, and which find suitable rest-
ing-places on the surface of the waters. The greenshanks (Totanus glottis)
has been obtained once in Florida, and apparently nowhere else in the United
States.

MIGRATION OF BIRDS. AY

and Newton, that the oceanic wandering of land-birds must be
attributed in most, or nearly all, cases to accidental circumstances—
namely, storms, or the prevalence of certain winds—which may
have wafted the birds beyond their control off to sea. Winds
from the west, as has been shown by Professor Baird, are preva-
lent between latitudes 32° and 58° N., and, hence, would be liable
to catch such birds as may be passing southward during their au-
tumnal migration, especially there where their flight would be
at some distance off from the shore, or across broad arms or in-
lets of the sea. The dispersal would naturally be facilitated by
the interaction of a heavy storm, and it is a most noteworthy

confirmatory fact that the appearance of American birds on the
' European coast is either presaged or accompanied by heavy westerly
winds blowing in that quarter. North of the fifty-eighth parallel
of latitude the polar winds trend westward, and with them we
have the accompanying transferrence of European birds, by way of
Iceland and Greenland, to the American continent. That storms
or heavy winds do influence the flight of birds in the manner here
described, is indisputably proved by the facts that present them-
selves in connection with the occurrence of marine birds over con-
tinental areas at some distance from the shore-line. The stormy
petrel, during and after the prevalence of a northeast storm, has
been seen in considerable numbers in the Eastern United States
beyond the Alleghany Mountains; the Thalassidroma Leachii has
been abundantly killed at or about the city of Washington; and
Professor Baird instances the case of a Pomarine jiiger (Cataractes
Pomarinus), which was killed on the Susquehanna, at Harrisburg,
in 1842.*° The golden plovers, in their southerly flight, start di-
rect from Nova Scotia or Newfoundland for the West Indies,
whence they continue their journey along the South American
coast to Patagonia. In this journey but comparatively few in-
dividuals touch or rest along the Atlantic States, yet it is known
that during heavy northeastern winds, in the month of August,
great numbers of the birds may be confidently expected along the
New England coast. And it not infrequently happens that un-
der similar conditions immense numbers of these and allied birds
are driven to very considerable distances in the interior of the
continents. In a like manner, during the prevalence of heavy
storms, European birds are cast upon the Azores, situated about

48 GEOGRAPHICAL DISTRIBUTION.

one thousand miles from the nearest continental coast. Among
these are the kestrel, hoopoe, oriole, and snow-bunting, and not
improbably also swallows, larks, and grebes.* If, then, birds
may be drifted by accidental storms to a distance of one thou-
sand miles in a direction contrary to that of the prevalent winds,
it may be asked, Why may they not be thus drifted, at least
after their first landing-place, another one thousand or two thou-
sand miles further? In other words, if European birds are carried
to the Azores, why are they not at intervals also transported from
there to the American coast? This question can, with our present
knowledge, not yet be answered. Three or four species of European
birds have been noticed in the Bermuda Islands—the wheat-ear (Saxi-
cola enanthe), the sky-lark (Alauda arvensis), the snipe (Gallinago
media), and the land-rail (Crex pratensis); but three of these are
also found in Greenland or on the North American mainland, while
the fourth, the sky-lark, appears to have been brought over in, or
to have escaped from, a ship.t In an ocean studded with islands,

* Most of the resident land-birds of the Azores are identical with forms
found in Europe and North Africa, and it, therefore, becomes impossible to
ascertain how many of the individuals actually peopling the islands may xoé
have been recently transported from the mainland. It is only under excep-
tional circumstances — barring the case of recognised stragylers —that such
wanderers can be determined.

+ The total number of European birds known to have found their way
across the Atlantic to the American shores (including Greenland) is, accord-
ing to Freke (‘+ Zoologist,’’ 1881), thirty-seven, of which Greenland counts
about thirty, and the Eastern United States only twelve. This determination
naturally excludes all birds that have been artificially introduced. Of the
twelve species occurring in the Eastern United States, six are swimmers and
five waders, and only one (and that somewhat doubtful, Buteo vulgaris, re-
ported to have been obtained in Michigan, in October, 18738) is a true land-
bird. The wheat-ear, referred to as occurring in the Bermudas, is considered
a member of the North American fauna. The number of species of American
birds crossing the Atlantic in the contrary direction is, according to the same
authority (“* Proc. Royal Dublin Soce.,’’ 1881), sixty-nine, of which twenty- two
are swimmers, sixteen waders, and no less than thirty-one land-birds. The
last include, among other forms, representatives of the genera Turdus (four
species), Galeoscoptes, Regulus, Dendreca, Hirundo, Loxia, Zonotrichia,
Ceryle, Coceyzus, Picus, and several species of birds of prey. The bald-
headed eazle has been recorded from Sweden. It is significant that, of the
forty-seven species of waders and land-birds, only two are known from Ice-
land (Falco candicans and Numenius Hudsonicus) and none from the Faroe

“BIRDS OF THE GALAPAGOS. 49

which afford numerous resting-places, it would not seem difficult
to account for the occurrence of land-birds at the remotest dis-
tances from the mainland, even without having recourse to the
accessory transporting agency of prevalent winds and storms. But
even with this favourable condition added, it would appear that
most land-birds are not disposed to undertake of their own free
will extended oceanic journeys, as is proved by the avi-fauna of
many of the oceanic islands. Thus, while, as we have already
seen, nearly all the representatives of the bird-fauna of the Azores,
situated more than one thousand miles from the mainland, are
identical with forms inhabiting either Europe or Northern Africa,
indicating that the islands were peopled in comparatively recent
times from those continents, in the Galapagos, situated only six
hundred miles off the west coast of the continent of South Amer-
ica, we meet with an entirely different state of things as regards
the bird-fauna. Of about thirty species of indigenous land-birds,
apparently only one, the common rice-bird (Dolichonyx oryzivorus),
which ranges from Canada to Paraguay, is absolutely identical with
a form found outside the limits of the island group. In addition
to this a species of owl (Asio Galapagoensis) is considered by some
authors to be but a mere variety of the cosmopolitan Asio brachy-
otus, or short-eared owl, which is distributed from China to Ire-
land, and from Greenland to Patagonia.** We have here, there-
fore, positive evidence that migrant stragglers from the South
American continent are at the best of but very rare occurrence,
and, on the other hand, visitors from the islands to the mainland
appear to be equally rare. But since, from the resemblance which
the fauna as a whole presents to that of the mainland, it is practi-
cally proved that the same was at one time derived by migration
from the continental areas—the islands being of volcanic origin—
it is manifest that this migration must have taken place at a period
sufficiently remote to have permitted the differences separating the
two faunas to have been brought about. On the other hand, the
absolute identity of the rice-bird with the similar form from the
continent, proves, as has been pointed out by Wallace, that the
island breed has been kept unaltered only through repeated or fre-

Isles. The easterly dispersion is attributed to causes identical with those
which have been assigned in explanation of the phenomenon by Professor
Baird.

50 GEOGRAPHICAL DISTRIBUTION.

quent visits from the specific congeners on the mainland. Not
only are, with the one or two exceptions above noted, all the
Galapagos land-birds specifically distinct from those found any-
where else,* but they also belong largely to distinct genera. Of
the fourteen genera represented, four are peculiar to the islands.
The rarity of continental visitors to the Galapagos, as compared
with the Azores, is to be attributed to the circumstance that these
islands are situated in a zone characterised by an absence of storm
winds. In the island of Juan Fernandez, situated in latitude 34°
S., and only four hundred miles from the Chilian coast, there are
but five species of land-birds, and of this number two are peculiar.
In the Keeling or Cocos Archipelago, situated in the Indian Ocean
at about the same distance from the Sumatran coast as are the
Galapagos from the coast of South America, there is not a single
species of true (indigenous) land-bird, although snipes and rails
of the common Malayan species are sufficiently abundant; and the
same is true in the case of the island of St. Helena, situated eleven
hundred miles from the nearest point of the continent of Africa.t
Of the twenty species of Passeres, or perching-birds, inhabiting the
Sandwich Islands—about the most strictly oceanic of any group of
oceanic islands so-called, being situated fully two thousand miles
from the nearest continental coast-line, and the same distance from
the nearest island groups (Marquesas and Aleutian), if we except the
small and almost tenantless shell and coral reefs—all the forms are
peculiar; and, furthermore, in all cases but one or two they belong
to genera which are likewise confined to the islands. And even of
the twenty-four or more species of aquatic and wading birds that
have been observed on or about the islands, five—a coot (Fulica
alai), a moor-hen (Gallinula Sandvichensis), a rail (Pennula Millei),
and two ducks (Anas Wyvilliana and Bernicla Sandvichensis)—are
peculiar.*? All in all there are some fifty species of birds known
from the island group, of which about one-half are peculiar.
It is evident that migrants (true land-birds) from distantly re-
moved countries but rarely arrive here. In the case of the Ber-

* The Dendreeca aureola, a species of wood-warbler closely allied to the
“golden”? or summer warbler of the United States (D. xstiva), is only doubt-
fully separable from the D. petechia of the Island of Jamaica.

+ A small wading-bird of the genus Aigialitis (ZZ. Sanctee Helene), allied
to a species of plover common in South Africa, is found in the island.

DISPERSAL OF BIRDS AND INSECTS. ok

muda Islands, which are distant from seven hundred to eight
hundred miles from the nearest coast, we meet with a different
order of things. The bird-fauna of these islands consists in all of
about one hundred and eighty species, including both the land and
aquatic forms, of which number, however, about thirty have been
noticed only on one occasion. Of the eighty-five species of land-
birds less than ten are permanent residents, the rest making their
way principally from the North American continent and the West
India islands.** It is a singular circumstance that most of the
foreign invaders are strictly migrating birds, whose course of mi-
gration lies along the Atlantic coast, and which in their periodical
wanderings frequently pass at some considerable distance out to
sea. Entering the region of violent winds and hurricanes, they
are liable to be snatched from their track, and to be forcibly trans-
ported to some remote shore, where, of necessity, they will be
compelled to secure for themselves a new home, and where, through
frequent visitations of a like character, the original breeds estab-
lished will remain pure and unaltered. Such is the condition of
thesbird-fauna of the Bermudas at the present time. None of the
strictly non-migratory birds are represented in those islands. Two
or more species of bat, also North American forms, are, with the
exception of rats and mice, the only indigenous mammals.
Dispersal of Insects.—It is a well-known fact that insects have
been found in nearly all parts of the world that have thus far been
trod by man, from the extreme limits of the Arctic and Antarctic
regions to the Equator, and from the level of the sea to—and con-
siderably above—the line of perpetual snow. Butterflies were ob-
served by the naturalists of the ‘‘ Alert” and ‘‘ Discovery” nearly
as far north as the eighty-third parallel of latitude; and Hum-
boldt met with insects on Chimborazo, at an elevation of upwards
of 18,000 feet. They are found in fresh and salt waters, freely
swimming on the surface—and at very considerable distances from
the mainland—as well as below it; in hot springs, where the water
has attained to a moderately high temperature, and in subterrancan
caves. But, while the members of this class of animals, taken col-
lectively, appear to be specially adapted to all the various condi-
tions of existence that might be imposed upon them by accidental
circumstances, the same does not hold for the individual members
composing the class. Thus, certain insects are entirely dependent

52 GEOGRAPHICAL DISTRIBUTION.

upon some special vegetable product for their existence, whether it
be, as it may happen, the leaf, the flower, or the juice of the plant
in question. Again, while in some cases the adult insect may be
entirely independent of such a circumscribed food-supply, the larva
may still be governed in its diet by a particular kind, without
which, consequently, the prolonged reproduction of the species
would be impossible. Such instances of limitation are exhibited
by numerous forms of caterpillars. Hence, it is not difficult to com-
prehend why, in regions which are affected by similar conditions of
climate, and which collectively show a general correspondence in
the character of the vegetation, certain species of insects should be
found at one locality and not at another, even where no physical
barrier separating the two should be interposed. In fact, the bar-
rier interposed by conditions of vegetable growth is fully as effective
in restraining a broad specific distribution as are the barriers re-
sulting from the physical conditions of the earth’s surface, most
of which they are able to overcome, either voluntarily or involun-
tarily. The mature insect, from its lightness, is frequently carried
away in aerial currents from its native or favourite haunts to regions
widely remote, in a manner precisely similar to what obtains in the
case of birds. Hawk-moths have been caught on board ship at a
distance of two hundred and fifty miles from shore, and a large
Indian beetle (Chrysochroa ocellata) was captured some years ago,
in the Bay of Bengal, at a distance of two hundred and seventy
miles from the nearest land. During Captain King’s expedition to
the Straits of Magellan dragon-flies flew on board his vessel when
still fifty miles out at sea (south of the Rio de la Plata); and Admi-
ral Smyth reports that, in the Mediterranean, myriads of flies were
brought to his ship by a southerly wind from a region fully one
hundred miles distant. A beetle is recorded by Darwin as having
been caught aboard the ‘‘ Beagle” when the vessel was upwards of
forty miles distant from the nearest shore; from what actual dis-
tance the insect may have come could, necessarily, not be deter-
mined. A locust was observed by the same naturalist three hundred
and seventy miles from land; and in 1844 swarms of these insects,
‘several miles in extent, and as thick as the flakes in a heavy
snow-storm, visited Madeira. These must have come with perfect
safety more than three hundred miles, and, as they continued flying
over the island for a long time, they could evidently have travelled

DISPERSAL OF MOLLUSKS. ia

to a much greater distance.” ** In addition to this means of aerial
dispersion, the distribution of insects may be to a great extent ef-
fected in the condition of eggs, which retain a considerable amount
of vitality, and which are not infrequently laid in decaying timber
and in the living tissues of various plants. When, therefore, float-
ing rafts or mats are apt to be formed, and to be floated out to sea,
it is almost certain that with them will be carried out a host of in-
sects—whether in the perfect form, as grubs, or as eggs—of different
species, a fair proportion of which will, doubtless, have retained
their vitality even after a protracted sea-voyage of several thousand
miles. It is in this manner that many or most of the tropical forms
which periodically make their appearance on the British coast have
been transported thither, the current of the Gulf Stream, which
trends in a general northeasterly direction, being instrumental in
drifting tropical log-wood to the trans-Atlantic temperate shores.
Dispersal of Mollusks.—The world-wide distribution of the
fresh-water and terrestrial Mollusca, and the occurrence of identical
or very nearly allied generic forms at opposite quarters of the globe,
prove conclusively that the animals of this class are favoured with
special instrumentalities by which a broad distribution is effected.
Land-snails of the genus Helix are found in all the continental
areas, from the polar regions to the Equator, and from the limit of
perpetual snow on mountain summits to the level of the sea; they
are also found in all the oceanic islands, even the most remote, that
have thus far been visited. The exact nature of this distribution
has not yet been positively determined, and, in fact, there are sev-
eral difficulties in the way of accounting for it. It is well known
that these animals cannot survive for any length of time the effects
of salt water, and this water is almost immediately fatal to the
vitality of the eggs. Hence, only under exceptional conditions is
it possible to account for a transferrence over a broad expanse of
oceanic surface. But it has been ascertained that such forms as are
capable of secreting an epiphragm, and therewith closing up the
entrance to the shell, are able to resist the injurious effects of salt
water for a very considerable period, in some instances as much as
two weeks, or more, as has actually been determined experimentally
by the immersion of land-shells in the briny medium. In regard to
these, therefore, there will be no difficulty in accounting for a broad
distribution, since they, and especially the genus Helix of all others,

54 GEOGRAPHICAL DISTRIBUTION.

would be liable to be concealed in and transported away by floating
timbers. In this manner they could be drifted away for several hun-
dreds of miles, and, under exceptionally favourable circumstances,
to possibly one or two thousand, the more readily since some of
these animals possess an enormous amount of vital tenacity, even
under the most adverse conditions of existence. Thus, a Helix from
North Africa (H. desertorum), contained in the British Museum
collection, and glued on to a tablet, was found by the conservators
to be alive after a period of more than four years. A similar in-
stance of resuscitation, although after a less protracted period, has
been noted in the case of one of the tabulated snails of the Acade-
my of Natural Sciences of Philadelphia. Again, it has been con-
clusively shown by Darwin and others that the eggs of pond and
other fresh-water bivalve-mollusks are occasionally found attached to
the feet of wading-birds—ducks, and the like—visiting such waters,
and are by them liable to be carried to very considerable distances
from their true homes, and thereby to have their range almost
illimitably widened. Such a method of transport, although exer-
cised to a much more limited extent, has been observed to be effect-
ed even by species of water-beetle, whose legs may have become
entrapped between the valves of the shell, as well as by newts and
other amphibians. The broad distribution of allied or identical
generic and specific forms of fluviatile mollusks over the most ex-
tended or widely remote geographical areas reccives a partial ex-
planation in the circumstance that the physical forces operating
upon the earth’s crust, causing movements in it of a differential
character—i. e., elevation at one point and subsidence at another—
tend to destroy the permanency of river courses, turning them now
to one side, then to another, and ultimately, possibly, uniting the
basins of streams whose waters were at one time quite remote from
each other. With this union or coalescence of the waters there
will necessarily also be a union of the contained molluscan faunas,
and, by a repetition of the process, a general transferrence may
in course of time be effected of the same or but barely modified
forms over the most distant portions of the earth’s surface. Ex-
istence, under the new conditions of habitation, will be rendered
possible or materially facilitated by the comparatively slight al-
teration in its physical properties to which the watery medium
will in many or most cases be subjected.

IN:

Zoological regions.—Holaretic realm.—Neotropical.—Ethiopian.—Oriental.—
Australian.— Polynesian.— Tyrrhenian, Sonoran, and Austro- Malaysian
transition regions.

ZOOLOGICAL REGIONS.

As an outcome of the laws governing distribution, and the
varying adaptabilities of animal organisms to overcoming the many
conditions of existence which present themselves on the surface of
the earth, it has resulted that different assemblages or groups of
animals have been thrown into different quarters of the habitable
globe, which may, accordingly, be said to be divided into a num-
ber of regions, of greater or less extent, each of which is character-
ised by its own particular fauna. To the more comprehensive of
such zoological divisions the term ‘‘region” or ‘‘realm” has been
applied by scientists. But just as the earth’s surface taken collec-
tively may be divided into zoological regions, so may these be
again further subdivided into minor regions, these still further, and
so on, until we have, as generally recognised, ‘‘regions,” ‘‘sub-
regions,” ‘* provinces,” and ‘‘sub-provinces.”

By most naturalists the terrestrial portion of the earth’s sur-
face is recognised as consisting of six primary zoological regions,
which correspond in considerable part with the continental masses
of geographers. These six regions are: 1. The Palearctic, which
comprises Europe, temperate Asia (with Japan), and Africa north
of the Atlas Mountains; also, the numerous oceanic islands, with
Iceland, of the North Atlantic. 2. The Ethiopian, embracing all
of Africa south of the Atlas Mountains, the southern portion of
the Arabian Peninsula, Madagascar, and the Mascarene Islands,
and which, consequently, nearly coincides in its entirety with the
Africa of geographers. 8. The Indian or Oriental, which embraces

56 GEOGRAPHICAL DISTRIBUTION.

India south of the Himalaya, Farther India, Southern China, Suma-
tra, Java, Bali, Borneo, and the Philippines. 4. Australian, com-
prising the continent of Australia, with Papua or New Guinea,
Celebes, Lombok, and the numerous oceanic islands of the Pacific.
5. The Nearctic, which embraces Greenland, and the greater por-
tion of the continent of North America (excluding Mexico); and,
6. The Neotropical, corresponding to the continent of South Amer-
ica, with Central America, the West Indies, and the greater por-
tion of Mexico. A seventh region has been established by some
authors to receive New Zealand; but there would seem not to be
sufficient reasons for isolating this island, or group of islands, from
the Australian region.

While the regions here designated are to a great extent clearly
defined by their zoological characters, it would, nevertheless, ap-
pear more in consonance with actual facts to depart somewhat
from their generally recognised limitations. Thus, the Palearctic
and Nearctic tracts, in the absence of both positive and negative
faunal characters of sufficient importance to separate them from
each other, are indisputably linked together, and should constitute
but a single region (the Holarctic). On the other hand, the scat-
tered island groups of the Pacific, which have been united with the
Australian realm, may with sufficient reason be constituted into an
independent region of their own; at any rate, they appear to bear
no special relationship with the Australian region, any more than
with the Oriental. Again, it seems advisable to separate from what
has hitherto been known as the Palearctic region the tract that is
comprised within the ‘‘ Mediterranean sub-region ”—i. e., the pen-
insular portion of Southern Europe, North Africa, and, in Asia, Asia
Minor, Persia, Afghanistan, Beloochistan, and the northern half of
Arabia—and to consider it by reason of its faunal association as a
‘connecting ”’ or intermediate region between the Holarctic, Ethio-
pian, and Oriental. A similar, although not yet clearly defined,
intermediate region, comprising in a general way Lower California,
the province of Sonora in Mexico, Arizona, New Mexico, and parts
of Texas, Nevada, and California, with probably also the extremity
of the peninsula of Florida, connects the western division of the
Holarctic realm with the Neotropical; and in the Eastern Hemi-
sphere, the Austro-Malaysian islands lying to the east of Bali and
Borneo, as far as, and inclusive of, the Solomon Islands, form a

ZOOLOGICAL REGIONS.—HOLARCTIC REALM. 57

transitionary tract between the Oriental, the Australian, and Poly-
nesian realms.
The major faunal divisions of the-globe are, therefore:
1. The Holarctic realm,
. Neotropical realm.
. Ethiopian realm.
. Oriental realm.
. Australian realm.
. Polynesian realm.
a. Tyrrhenian, or Mediterranean transition region.
6. Sonoran, or American transition region.
ec. Papuan, or Austro-Malaysian transition region.

co Ot me oO 0

THE HOLARCTIC REALM.

This division comprises the greater portion of the continent of
North America, the whole of Europe north of the Alpine chain of
mountains, and by far the larger half of the continent of Asia. It
is preeminently the region of the Temperate and Frigid zones, and
is, in fact, the only one into the consideration of whose organic
products a well-marked Arctic element enters. As here defined, it
comprises both the Palearctic and Nearctic regions of zoogeogra-
phers, which do not differ very essentially from each other in the
general characters of their faunas, or, at any rate, not nearly to the
extent that the other regions differ from each other, or these in-
dividually from any third. The southern limits of this Holarctic
tract, owing to the intermingling along the several border-lines
of its fauna with the faunas of the various other regions, is difficult
of precise determination; and there can be no doubt that what at
many points is considered to belong properly to one region belongs
just as properly to another. But such ‘‘debatable grounds” be-
tween two regions will occur in the case of any other two regions,
and likewise in the case of the minor divisions—sub-regions, prov-
inces, etc. In the Western Hemisphere the debatable lands between
the Holarctic and the Neotropical realms cover a considerable por-
tion of the Southwestern United States—namely, Arizona, New
Mexico, and parts of Texas, Nevada, and California, a tract of ter-
ritory generally included in the Nearctic region of most zooge-
ographers. But there can be no question that the preponderating
faunal ne in this tract is that of the region farther to the

58 GEOGRAPHICAL DISTRIBUTION.

south, the Neotropical; and the same can probably be said of the
extremity of the peninsula of Florida. With these limitations the
Holarctic in the Western Hemisphere embraces the whole of the
United States, and all the region stretching thence northward
towards and into the Arctic Sea. In the Eastern Hemisphere the
southern boundary may in a general way be said to be the moun-
tain complex which, as the Pyrenees, Alps, Balkans, and Caucasus,
traverses the south of Europe from the Bay of Biscay to the Cas-
pian, the northern line of Persia and Afghanistan, the Hima-
laya Mountains, and the Nanling range in China, which forms the
southern water-shed to the Yangtse-Kiang. These various boun-
daries are principally of a physical nature, and of such a char-
acter as to be insurmountable to most animals.

No other region can compare with the Holarctic in the mani-
fold variety of its physical characteristics. Every form of terres-
trial configuration, or condition of soil or climate, that may be rep-
resented in any other region, is also represented here, and on an
imposing scale. From the ice-bound fields of the far north to
the burning desert wastes of Turkestan on the south, and from the
deep forest-grown lowlands to mountain summits soaring thou-
sands of feet above the level of perpetual snow, we pass through
all those various gradations of climate which respectively charac-
terise the Frigid, Temperate, and Torrid zones. Densely covered
forest tracts, supporting, as in the north, a sombre growth of pine
and other coniferous trees, or, as in the south, a vegetation of
almost tropical luxuriance, alternate with broadly open grass or
pasture lands (twndras of Siberia, American prairies and plains),
which in some cases support over enormous areas only a very scanty
vegetation, and in others display a profuse variety of vegetable
productions. It is in this region that, in addition to a most boun-
tiful development of desert tracts, we meet with the most elevated
table-land (the Central-Asian), and, at the same time, with the
greatest expanse of lowland on the surface of the globe, the great
plain of Siberia and Northeastern Europe.

For convenience of treatment, and to facilitate comparison with
other zoogeographical publications, the Old and New World divi-
sions of the Holarctic region will be considered separately.

The Old World or Eurasiatic Division (Palearctic region [in
part] of most authors).—The southern boundaries of this region

MAMMALS OF EURASIA. 59

have already been indicated. In the northwest and west it em-
braces Spitzbergen and Iceland, and the numerous larger and smaller
islands which lie between these and the mainland.

Although this division has an east and west extent not far short
of half the circumference of the globe, yet so great is its zoological
unity ‘‘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 Pale-
arctic 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.” *°

Zoology of the Eurasiatic Region.—Although the Eurasiatic
fauna comprises representatives of thirty distinct families of Mam-
malia, not a single one of these is absolutely confined, or is pecu-
liar, to that region. Perhaps on the whole its most distinctive
group of quadrupeds is that of the sheep and goats, forming the
sub-family Caprine of the Bovide (oxen). There are represented
in this group some twenty-two or twenty-three species (belonging
to the genera Capra and Ovibos), which, with four or five excep-
tions, are either absolutely confined within the limits of the re-
gion, or just pass beyond it. The genus Capra, comprising the
goats and ibexes on one side, and the sheep on the other, have
an outlying Old World representative—a goat—in the ‘‘ Warrya-
to” (Capra hylocrius) of the Neilgherries (Oriental realm), and an-
other—a sheep, the moufflon (C. [Ovis] musimon)—in the larger
islands (Corsica, Sardinia, Crete) of the Mediterranean, and the
mountains of Greece and Persia. A species of ibex (C. beden)
inhabits the elevated districts of Egypt, Syria, and Sinai, and an-
other (C, Valie), possibly only a variety of the preceding, the high-
lands of Abyssinia, just within the boundaries of the Ethiopian
realm. The two American representatives of the family, the Rocky
Mountain big-horn (C. [Ovis] montana) and the musk-ox (Ovibos
moschatus), are both absolutely confined to the Holarctic tract.
One, at least, of the two generally recognised species of camel,
the Bactrian or two-humped species (Camelus Bactrianus), is at the
present time entirely, or almost entirely, restricted to the Eur-
asiatic region, and not unlikely the dromedary (C. dromedarius)
was also at one time indigenous to it, although from the long-

60 GEOGRAPHICAL DISTRIBUTION.

continued subjection under which it has been held by man, whose
wanderings the animal has been forced to follow, it has become
almost impossible to determine the precise region constituting its
true home.

The extensive group of the antelopes, so highly indicative of the
Ethiopian region, are but very sparingly represented, the most char-
acteristic forms being the chamois (Rupicapra tragus), confined to
the elevated mountain summits of Southern Europe, from the Pyr-
enees to the Caucasus, and the saiga (Antelope saiga), an inhabitant
of the plains of Southeastern Russia and the adjoining country of
Asia. These are the only forms of antelope found in Europe; two
or three species inhabit the Thibetan plateau, and several goat-like
forms, of the genus Nemorhedas, range from the Eastern Himalayas
into China and Japan. The deer (Cervide) are sufficiently abun-
dant, and comprise among the more distinctive genera of the
region the roe-deer (Capreolus) and the eastern musk (Moschus),
the latter considered by many authors to constitute the type of
a distinct family (Moschide). The stag (Cervus elaphus) ranges
over nearly the whole of Europe, and eastward in Asia to Lake
Baikal and the Lena River. The only members of the Quadru-
mana, or monkeys, known to exist within the limits of the region
under consideration, belong to the genera Semnopithecus and Ma-
cacus, one species of the former (8. Roxellana) occurring in the
elevated mountain region of Eastern Thibet, in about latitude 32°,
and several of the latter likewise in Eastern Thibet, and also in
China and Japan. The Barbary monkey (Macacus inuus), a North
African species, which inhabits the Rock of Gibraltar, is the only
European representative of the order; but its habitat is located
within what has been designated the Tyrrhenian transition region.
The Carnivora constitute an important feature in the Eurasiatic
fauna, both by the number and variety of the individual forms
represented and by their broad geographical range. But the actual
number of carnivore genera specially distinctive of this fauna is
very limited. The badger (Meles), is found throughout Central and
Northern Europe and Asia, in Japan and China, in the latter country
extending its range as far south as Hong-Kong, or within the boun-
daries of the Oriental region. In brief, the most distinctive Eur-
asiatic mammalian genera may be said to be the following :

Talpa, the Mole.—Distributed throughout the entire region, and

MAMMALS OF EURASIA. 61

passing in Northern India beyond its limits into the Oriental re-
gion.

Meles, the Badger.—Temperate Eurasia, Palestine, Japan, and
China.

Camelus, the Camel.—At present distributed from the Sahara
northeastward throughout Western and Central Asia to the shores
of Lake Baikal, and the region of the Amoor.

Capreolus, the Roe-deer.—An inhabitant of temperate and Southern
Europe, and Western Asia, with a distinct species in North China.

Moschus, the Musk-deer.—Central Asia, from the Amoor and the
district of Peking to the Himalayas and the elevated peaks of Siam.

Poephaga, the Yak.—The elevated plains of Western Thibet.

Rupicapra, the Chamois.—Elevated mountain slopes of the Pyr-
enees, Alps, Carpathians, Balkans, Caucasus.

Saiga.—The Steppes of Southeastern Russia, and Western Asia.

Capra, the Sheep and Goats.—The former are found in a natural
state only in the mountain wilds of Corsica, Sardinia, and Crete,
and in Greece, Asia Minor, Persia, and Central and Northeast Asia.
The single American form, the big-horn, as above mentioned, is a
native of the Rocky Mountains. The goats are found throughout
nearly the whole of the South European Alpine region, from Spain
to the Caucasus, whence they extend their range through Armenia
and Persia to the Himalayas and China.

Myoxus, the Dormouse.—Found throughout the greater part of
the region.

Lagomys, the Pika, or Tailless Hare.—A group of small rodents,
whose distribution extends from the elevated slopes (11,000 to 14,000
feet) of the Central-Asian mountain system, and Southeastern Rus-
sia, north and northeastward to the Polar Sea, and the farthest
extremity of Siberia. The genus has a solitary representative in
North America.

Myogale, the Water-mole, or Desman.—A singular insectivorous
animal, resembling the water-rat, of which there are but two spe-
cies, one of them inhabiting the valleys along the northern face of
the Pyrenees, and the other the river banks of Southern Russia.

Of other well-known types which may be said to be character-
istic of, but which are not absolutely confined to, the Eurasiatic
region, are the reindeer (Rangifer), the elk (Alces), aurochs or
European bison (Bison)—now in a wild state confined to Lithuania

62 GEOGRAPHICAL DISTRIBUTION.

and the Caucasus—the polar bear (Thalassarctos), and the beaver
(Castor), all of which, comprising in each case but a single species,
appear to be, with the possible exception of the bison, specifically
identical with North American forms.

North American, or Nearctic Division.—The dominant feat-
ures of the North American mammalian fauna are preeminently
those which also stamp the character of the Eurasiatic fauna.
Thus, among the commoner animals we have the deer, moose or
elk, reindeer, bison (possibly identical with, or at least very closely
allied to, th European aurochs), cats, lynxes, weasels, bears, wolves,
foxes, the beaver, hares, squirrels, and marmots. Many of the forms
embraced in these types, moreover, are, as has already been stated,
specifically identical with their Eurasiatic congeners. But, while
there are such striking resemblances between the two faunas—re-
semblances that penetrate to almost all parts of the regions that are
under consideration—it cannot be denied that there are also a num-
ber of almost equally well-marked differences; but these are neither
sufficiently numerous, nor sufficiently important, to invalidate the
claims carried by the positive characters for uniting the two trans-
Atlantic divisions into one region, the Holarctic. The prepon-
‘derating element in the North American mammalian fauna (as,
indeed, also in the Eurasiatic) is furnished by the group of the
rodents, which here comprise nearly, or fully, one-half of all the
recognised mammalian forms. Of about twenty-six genera repre-
sented, nearly one-half are restricted, or are peculiar, to this re-
gion; but the actual number of specific forms embraced in these
peculiar genera scarcely numbers one-fourth of the total number
of species. The most distinctively North American families are
the Haploodontide, a very limited group (two species) of beaver-
like animals inhabiting the west coast, and the Saccomyide, or
pouched-rats and gophers (Saccomys, Geomys, Thomomys, &c.),
animals characteristic of the fauna of the Western plains and ele-
vated mountain regions. Among the rats and mice (Muridx) we
meet with, in addition to certain peculiar North American forms,
the genus Arvicola, the field-mouse, or vole, which has an extensive
representation throughout the temperate portions of the Eastern
Hemisphere as well; along with this animal we find the lemming
(Myodes), another Eurasiatic form. It is a singular fact, to be
noted in this connection, that the typical genus Mus, which in-

MAMMALS OF NORTH AMERICA. 63

cludes the common or domestic rats and mice, and which is rep-
resented on all the grand divisions of the Eastern Hemisphere, is
completely wanting, not only in North America, but in the entire
New World, where its place is taken by the closely-allied vesper-
mice, constituting the genus Hesperomys. The musk-rat (Fiber),
belonging to the same family, is not found outside the limits of the
North American continent, although its range extends into the
Neotropical realm (Mexico). The squirrels (Sciuridz) are princi-
pally Old World forms; they comprise the true squirrels (Sciurus),
flat-tailed flying squirrels (Sciuropterus), ground-shrews (Tamias),
marmots (Arctomys), and pouched-marmots, or spermophiles (Sper-
mophilus). In addition to these forms we are presented with the
curious animal known as prairie-dog (Cynomys), whose range is
confined to the central continental region. Among other rodents
may be mentioned the jumping-rat (Jaculus, or Zapus), allied to
the eastern jerboas, and the Canadian porcupine (Erethizon), be-
longing to a group of animals (Cercolabide) distinguished from
the true or Old World porcupines both structurally and in their
arboreal habits. The ungulates, or hoofed animals, have but a very
feeble development in the Nearctic division of the Holarctic realm.
The goats and sheep are, with two exceptions, the big-horn (Ovis
montana), an inhabitant of the Rocky Mountains, and the musk-ox
(Ovibos moschatus), from the Arctic district, completely wanting,
a faunal characteristic which eminently serves to distinguish the
western division of the Holarctic tract from the eastern, to which
almost the whole of this group of animals is confined. The ante-
lopes are limited to two species, representing two distinct types,
both of them confined to the more temperate regions of the conti-
nent. The one is the ‘‘prong-horn” of the Western plains (Anti-
locapra), and the other the Rocky Mountain goat (Aplocerus lani-
ger), which, as the name indicates, is partial to the mountain
fastnesses. Two varieties of the bison, or American buffalo, are
recognised—the buffalo of the plains, and the buffalo of the for-
ests and mountains; but the variation observable between these is
one pertaining to habit and not to structure, and therefore not of
specific importance. The Carnivora present several distinctively
American types, and notably so the raccoons (Procyonide), a small
group of interesting quadrupeds, whose home is primarily the
region of the tropics, and which appear to hold a somewhat inter-

64 GEOGRAPHICAL DISTRIBUTION.

mediate position between the weasels and bears. To the same
family belong the South American coatis (Nasua) and the prehen-
sile-tailed kinkajou (Cercoleptes). The Mustelide, or weasels, com-
prise the weasels proper, marten, ermine, mink, glutton, American
badger (Taxidea), skunk, American otter (Latax), and the singular
sea-otter (Enhydris), from the California coast. The most formi-
dable carnivores are the grizzly bear (Ursus horribilis), not im-
probably identical with the European brown-bear (U. arctos), and
the couguar, or American panther (Felis concolor), whose range
extends from the sixtieth parallel of north latitude to the southern
extremity of Patagonia. One species of implacental mammal—the
Virginian opossum (Didelphis Virginianus)—penetrates as far north
as the Canadian frontier.

Taking the Nearctic and Palearctic divisions of the Holarctic
region collectively—i. e., the region as a whole—we find it to be
characterised by the exclusive, or almost exclusive, possession of
the following families: Talpidz (moles), Trichechide (walruses),
Castorid (beavers), and Lagomydee (pikas); and if the reindeer,
moose, and sheep and goats, be considered as distinct families, as
is maintained by many naturalists, then also by the Rangiferide,
Alcidx, and Caprid. In addition to these seven families, we
have also the hares (Leporid) and bears (Ursidx), which, though
not exclusively restricted to these regions, are by their numbers
and vast distribution, eminently characteristic of them. Of about
one hundred and twenty genera represented, upwards of seventy
(or sixty per cent.) are found in no other region. Among the most
characteristic forms are—

In the Old World :

Talpa, the mole. Rupicapra, the chamois.
Meles, the badger. Saiga, the saiga antelope.
Camelus, the camel. Capra, the goat.
Capreolus, the roe-deer. Myoxus, the dormouse.
Moschus, the musk-deer. Myogale, the water-mole.

Poephaga, the yak.

In the New World:

Saccomys, pouched-rats or Ovibos, the musk-ox.
Geomys, gophers. Antilocapra, the prong-horn.

FAUNA OF THE HOLARCTIC REALM. 65

Thomomys, ) pouched-rats or Aplocerus, the Rocky Mountain
Dipodomys, + ce goat.
Perognathus, j Procyon, the raccoon.
Jaculus, the jumping-mouse. Mephitis, the skunk.
Fiber, the musk-rat. Latax, the American otter.
Cynomys, the prairie-dog.
Erethizon, the Canadian porcu-

pine.

Common to both divisions:

Lagomys, the pika. ; Bison, the bison.
Arctomys, the marmot. Rangifer, the reindeer.
Spermophilus, the pouched-mar- Alces, the elk.

mot. Thalassarctos, the polar bear.
Castor, the beaver. Gulo, the glutton.
Myodes, the lemming. Lyncus, the lynx, and most of the
Arvicola, the field-mouse. seals and the walruses.

Ovis, the sheep.

The bird-faunas of the Old and New World divisions of the
Holarctic tract differ very materially from each other, a condi-
tion in great measure explained by the circumstance that in both a
large representation is obtained through migration from extra-
limital regions. Thus, the Eurasiatic or Palearctic avifauna is
largely made up of types which are equally Ethiopian or Oriental;
and in like manner a very large proportion of the similar North
American fauna is made up of forms which might with equal
justice be considered Neotropical or Nearctic. But even in the
case of the resident birds, or such as may be considered to be more
properly belonging to the region, marked differences, suflicient to
characterise the two divisions, present themselves. The prepon-
derating Eurasiatic forms belong, among the perchers, to the
families of thrushes (Turdid)—with the cosmopolitan genus Tur-
dus; warblers (Sylviade), with the true warblers (Sylvia), red-
start, robin, and nightingale (Luscinia); nuthatches (Sittida), tits
(Paridz), Muscicapide (Old World fly-catchers), shrikes (Laniide),
crows (Corvide), with the pies, crows proper, and jays; swallows
(Hirundinide), finches (Fringillide)—gold-finch, haw-finch, cross-
bill, bull-finch, linnet, sparrow, grosbeak, lark-bunting, true finch

66 GEOGRAPHICAL DISTRIBUTION.

(Fringilla), and bunting (Emberiza), the last two almost exclusively
confined to this region (and the adjoining debatable tracts)—starlings
(Sturnide), larks (Alaudide), wag-tails (Motacillids), wood-peckers
(Picide), king-fishers (Alcedinid), swifts (Cypselide), and pigeons
(Columbide). All of these families, not a single one of which is
restricted to the Holarctic region, are, with the exception of the
starlings (Sturnide) and the fly-catchers (Muscicapide), likewise
distributed throughout the Nearctic division, of whose avifauna
they constitute a very important factor. In the New World the
true starlings are replaced by the family of hang-nests (Icteride),
to which the Baltimore bird (Icterus), bobolink (Dolichonyx), cow-
bird (Molothrus), and red-wing (Agelaius) belong. The Old World
fly-catchers have their representatives in the tyrant shrikes (Tyran-
nid), familiarly also known as fly-catchers. The true warblers
(Sylviadz) are but very feebly developed in the Nearctic division,
where, of about ten species, three are kinglets (Regulus), and three
blue-birds (Sialia); but their place is taken by a multitude of forms
belonging to the preeminently South American family of wood-
warblers (Mniotiltids). Of the Holarctic gallinaceous birds the
most distinctive forms in the eastern division are the true partridge
(Perdix), snow-partridge (Tetraogallus), capercaillie (Tetrao), true
pheasant (Phasianus), golden-pheasant (Thaumalia), tragopan (Ce-
riornis), and impeyan (Lophophorus), forms either exclusively re-
stricted to the region, or just passing beyond the boundaries; of
the western division, the California quail (Oreortyx), cupido (Cu-
pidonia), tree-grouse (Canace), sage-grouse (Centrocercus), and tur-
key (Meleagris). The ruffled-grouse (Bonasa) and ptarmigan (Lago-
pus) are common to the northern regions of both hemispheres. The
birds of prey comprise, throughout both divisions of the region, a
variety of eagles, falcons, hawks, buzzards, kites, and owls, and of
forms nearly all of which are also found in other portions of the
earth’s surface. America has no representative of the Old World
group of (true) vultures, forming the sub-family Vulturine, their
place being filled by the carrion vultures, or so-called turkey-buz-
zards (Cathartine). Of the wading-birds the Eurasiatic region alone
possesses the true bustard (Otis), the typical representative of a
family whose members are spread throughout Africa, Asia, and
Australia.

The Holarctic region is deficient in reptilian forms as compared

EUROPEAN REPTILE-FAUNA. 67

with the warmer regions of the earth’s surface, which appear to be
more suitable to the habits of this class of animals. In the whole
of Europe north of the Alps, or in what has been recognised as
the ‘‘European province,” naturalists recognise only about fifteen
species of snakes, and a nearly equal number of lizards ; in the
Nearctic division, while the number of lizards is not very much
greater—about twenty species—that of serpents is very materially
increased—to about eighty to ninety species—most of them belong-
ing to the family of colubers, which includes the black constrictors.
The headquarters of the rattlesnakes are situated in the debatable
land bordering the Neotropical realm.

The entire reptile-fauna of Europe is, according to Schreiber
(‘‘ Herpetologia Europea,” 1875), comprised in sixty-two species,
of which twenty-five are serpents, thirty-two saurians, and five che-
lonians. Northern Europe, or the region lying to the north of the
fifty-fifth parallel of latitude, is represented by but six species:
Viperus (Pelias) berus, Tropidonotus natrix, Coronella Austriaca,
Anguis fragilis, Lacerta vivipara, and L. agilis; the chelonians are
completely wanting in this tract. Central Europe, including the
Alpine system of mountains, has twenty-nine species, while the en-
tire number is represented in the Mediterranean fauna. A number
of additional species has been added to the list enumerated by
Schreiber; but these do not materially affect the ratio for the dif-
ferent zones. The most northerly of all serpents appears to be the
common European viper, Viperus (Pelias) berus, whose range in
Scandinavia extends to about the sixty-seventh parallel of latitude.
The species is distributed throughout nearly the whole of Europe,
and eastward through Central Asia to the Japanese islands; it is
also found in England and Scotland, and in some of the Scotch
islands (Arran, Hebrides). Tropidonotus natrix (Natrix vulgaris),
a species of equally broad distribution, which is stated to ascend
mountains to a height of six thousand feet, is found in Norway as
far north as the sixty-fifth parallel.

The most northerly, and at the same time most broadly distrib-
uted, species of European lizard is the Lacerta vivipara, whose range
in Norway is extended by Collett to the seventieth parallel of lati-
tude. It is found throughout most of Europe (wanting in the Ibe-
rian Peninsula, Southern Italy, and Greece), and is an inhabitant of
the Alpine region, up to an elevation of nine thousand feet.

68 GEOGRAPHICAL DISTRIBUTION.

While the Holarctic region is relatively meagre in its reptilian
fauna, it is preeminently the home of the tailed amphibians, newts,
salamanders, &c., of which we have the blind proteus (Proteus
anguinus), in the cavern-waters of Carinthia, Carniola, and Istria;
the giant salamander, known as Sieboldia (Cryptobranchus), in
Japan, and its allied American form, the menopoma, the eel-like
sirens, mud-puppies (Necturus), and almost limbless amphiumes of
the Eastern and Southern United States; the true salamander and
triton in Europe and Asia, and their American representatives, the
amblystomes, to which the singular form known as the axolotl be-
longs. The European tail-less amphibians (frogs and toads) number
some dozen or more species of the genera Bombinator, Pelobates,
Alytes, Hyla, Discoglossus, Rana, and Bufo, the most broadly dis-
tributed of which appears to be Rana temporaria and R. esculenta,
the former extending its range eastward to Japan and America, and
northward in Norway to beyond the seventieth parallel of latitude.

The fish-fauna of the Holarctic tract is characterised by the spe-
cial development, among fresh-water forms, of the carps (Cypri-
nidz), salmon (Salmonide), pikes (Esocide), perches (Percide),
sculpins or bull-heads (Cottidee), sticklebacks (Gasterosteide), stur-
geons (Accipenseridz), and lampreys (Petromyzon), which are dis-
tributed over both the eastern and western divisions of the region.
The Cyprinoids are especially abundant, constituting, in the number
of species, according to Giinther (Ency. Brit., XII., p. 675), nearly
two-thirds (two hundred and fifteen species) of the entire fish-fauna
of temperate Europe (including the Mediterranean transition region)
and Asia, and more than one-third (one hundred and thirty-five
species) of the equivalent fauna of North America. The cat-fishes
(Siluridz), so eminently characteristic of the more southerly equa-
torial zone, are largely deficient in the number of species. Silurus
occurs in some of the Eurasiatic waters as an immigrant from India;
most of the North American forms belong to the genus Amiurus.
Among the more distinctive ichthyic features separating the faunas
of the eastern and western divisions of the Holarctic realm are the
possession, by the former, of the barbels (Barbus) and cobitoids,
and, by the latter, of the suckers (Catostomide), sun-fishes (Cen-
trarchide, most abundant in the Mississippi Valley), and two genera
of ganoid fishes, Amia and Lepidosteus, both of which occur as
fossils in the Tertiary deposits of North America, and the latter

HOLARCTIC SUB-REGIONS. 69

also in Europe. On the other hand, the two regions exhibit a
marked inter-relationship by the possession of a number of identical
specific forms, as Accipenser sturio (sturgeon), Perca fluviatilis
(perch), Salmo salar (salmon), Esox lucius (pike), Lota vulgaris
(ling), &c.

The correspondence existing between the vertebrate faunas of
the Old and the New World divisions of the Holarctic tract extends
also to the Invertebrata, and is especially marked in the case of the
beetles (Staphylinidz, Carabide), butterflies, and the land and
fresh-water mollusks (Limnea, Planorbis, Physa, Paludina, Val-
vata). The land-snails (Helicide) and naiades (Unionide) are very
largely developed, the latter more particularly in the American
streams, where distinctive types appear to be relegated to the dif-
ferent water-courses. The eastern melanians are wholly wanting
in America, where they are replaced (principally to the east of the
Mississippi River) by the members of the allied family of the Stre-
pomatides (Io, Goniobasis, &c.).

The Holarctic realm may be conveniently divided into the fol-
lowing sub-regions:

1. The Boreal Sub-Region, which extends northward into the
Polar Sea, and whose southern confines are fixed approximately by
the northern limits of the cultivation of the cereals, and the southern
limits of the migration of the reindeer. In the Western Hemisphere
it comprises most of the region lying to the north of the United
States and Canada boundary-line, and in Eurasia the tract lying
north of a line starting from about the sixty-sixth parallel of latitude,
on the Norwegian coast, and passing southeastward to the East Asiat-
ic coast, in about latitude fifty degrees north. The fauna of this
region is a very homogeneous one, and, generally speaking, also a
limited one. Among the more distinctive mammalian forms, which
comprise almost exclusively only ruminants, carnivores, and rodents,
are the Arctic fox (Canis lagopus), polar-bear, glutton, ermine, mink,
sable, walrus, variable hare, lemming, and reindeer. The musk-ox,
which occurs fossil in the Quaternary deposits of Europe, is at the
present time found only in America. Among the more character-
istic birds are the snow-partridges (Lagopus), snowy-owl (Surnia
nivea), Iceland falcon (Falco candicans), eider-duck (Somateria mol-
lissima), and various alks (Alca), divers (Colymbus), and guillemots
(Uria, Lomvia). Captain Markham observed the footprints of the

70 GEOGRAPHICAL DISTRIBUTION.

polar-hare in the snow-bound ice in latitude 83° 10’, and the antlers
of a reindeer were picked up by the officers under Sir George Nares,
in latitude 82° 45’ (Grinnell Land). A skeleton of the latter ani-
mal, recently picked by wolves, was also obtained in latitude 80°
27’. Traces of the rock-ptarmigan (Lagopus rupestris) have been
met with as far north as latitude 83° 6’, and the snow-bunting (Plec-
trophanes nivalis) in latitude 82° 33’. The reptile-fauna is very
limited, no serpent, apparently, passing beyond the sixty-seventh
parallel of latitude, and no lizard above the seventieth. The fishes,
which include the common perch and pike, are mainly Salmonoids.
Insects are fairly numerous, and even in the far north the number
of species is considerable. Sir George Nares obtained no less than
forty-five species, representing nearly all the orders (including Lepi-
doptera) in Grinnell Land; Greenland has thus far yielded eighty
species, and Iceland three hundred. Among the most northerly
genera of non-marine mollusks are Helix, Pupa, Succinea, Limnza,
and Planorbis.

2. The European Sub-Region, which includes practically the whole
of Europe lying between the Arctic tract and the Alpine system of
mountains, extending southeastward and eastward to the Caucasus
and the Caspian steppes. The fauna of this region is typically
that of temperate Eurasia, taken as a whole, and therefore requires
no elaborate analysis. Among its more or less characteristic Mam-
malia are the moose or elk (in the north), stag, roe, aurochs (Bison
Europzus, in the Caucasus and the forests of Lithuania), the Alpine
chamois and ibex (with the accompanying marmot, Arctomys mar-
motta), brown bear (Ursus arctos), badger, glutton, dormouse,
hamster (Cricetus frumentarius), mole (Talpa Europea), and hedge-
hog (Erinaceus Europeus), many of which also form integral parts
of the Arctic and Central Asian faunas. The birds comprise sev-
eral hundred species, of which Germany alone possesses nearly three
hundred; distinctive types are, however, not numerous—indeed,
they may be said to be almost wholly wanting—and even the num-
ber of restricted forms is very limited. Among these may be men-
tioned a number of song-birds of the finch tribe, as the chaffinch
(Fringilla celebs), siskin (F. spinus), goldfinch (F. carduelis), bull-
finch (Pyrrhula rubricilla), yellow-hammer (Emberiza citrinella),
and linnet (Linota linaria), and the nightingale (Luscinia). The
most distinctive bird of prey is the bearded vulture of the Alps, or

FAUNA OF CENTRAL ASIA. vii

limmergeier (Gypaétus barbatus). The reptilian-fauna, as has
already been remarked, when treating of the Eurasiatic region
generally, is very limited. Among the poisonous serpents are the
Pelias berus and the sand-viper (Vipera ammodytes), the range of
the latter extending from the Mediterranean into Sweden.

3. The Central Asian Sub-Region comprises that portion of the
Holarctic tract which lies south of the Arctic sub-region, and is
included between the European sub-region on the west and China
proper and Manchuria on the east. A steppe character prevails
in the western portion of this region, to which desert features are
also added, and hence we find a distinct individuality imparted to
its fauna. The rodents, whose most distinctive forms are the
spermophiles and jumping-mice (Dipus, Scirtetes), are more ex-
tensively developed than in the European tract; on the other hand,
the larger Carnivora are almost completely wanting, although the
tiger seems to occasionally reach the region about the Caspian and
Aral seas. The deer are replaced by one or more forms of ante-
lope (Saiga), which, with the exception of the camel and some wild
equine representatives, are almost the sole hoofed animals of the
region. A distinctive faunal feature is constituted by the seals of
the Caspian (Phoca Caspica), which appear to be very closely related
to the common Phoca vitulina of the North Atlantic. Among the
birds may be mentioned the steppe partridges (Pterocles, Syr-
rhaptes), and, as an occasional visitor, not improbably also the
ostrich. Reptiles are fairly abundant, and include among the
lizards the agamid genus Stellio, and among serpents the sand-
snake (Psammophis) and the poisonous Trigonocephalus.

In the eastern half of the Central Asian sub-region, plateau and
desert features largely predominate, and the fauna acquires some-
what distinctive characters. The ungulate and carnivore types of
Mammalia are more abundantly represented, the former comprising,
in addition to the camel (Camelus Bactrianus), whose range ex-
tends to the shores of Lake Baikal, and two or more species of
antelope, the dziggetai or kiang (Equus hemionus) of the plains of
Thibet, the recently-discovered species of wild horse described by
M. Poliakoff as Equus Przevalskii, the Thibetan yak, several wild
goats, and the argali (Ovis argali), the last recalling the big-horn
of the Rocky Mountains. The tiger and ounce (Felis uncia) both
range across the region into Siberia, sharing the habitat of the

12 GEOGRAPHICAL DISTRIBUTION.

snow-leopard (Felis irbis). The grouse, partridges, steppe part-
ridges, and bustards constitute important elements in the bird-
fauna, which exhibits the general features of the north temperate
region.

4, The Manchurian Sub-Region embraces Manchuria, Northern
China (with a westerly extension along the northern face of the
Himalayas), and the Japanese islands. The fauna, especially in
the more southern districts, exhibits characters drawn from both
the Tropical and Temperate zones. A distinguishing feature of
this sub-region is the presence of monkeys, which are represented
by the genera Macacus and Semnopithecus, the former penetrating
even into Japan. The Cervide, whose range extends into Japan
(where the antelope is also met with), are represented by both
horned (Elaphodus) and hornless species (Hydropotes, Lophotra-
gus), and by the diminutive musk-deer (Moschus moschiferus),
which inhabits the mountain-valleys from the Amur to the Hima-
layas. The edentates have their most northerly representative in
the scaly Manis (Japan). Among the more distinctive carnivore
forms are the genera Lutronectes, Ailuropus, and Nyctereutes.
The facies of the Japanese bird-fauna is distinctly European, but
in China, which is properly the home of the pheasants, there is a
considerable intermixture of tropical (Oriental, &c.) forms, such as
the babbling-thrushes, caterpillar-eaters, honey-suckers, and weaver-
finches.

5. The Alleghanian Sub- Region may be approximately defined as
comprising that portion of the Holarctic realm in the Western
Hemisphere which lies south of the Arctic tract and east of the
one hundredth meridian of west longitude (Greenwich). Its faunal
features are those of the North American or Nearctic division gen-
erally, although among the Mammalia a deficiency is brought about
by the absence of some of the pouched-rats or gophers, the big-
horn (Ovis montana), the Rocky Mountain goat (Aplocerus lani-
ger), and the musk-ox, which, with the exception of the last, belong
to, or are most abundant in, the central or Rocky Mountain sub-
region. The majority of the Arctic Carnivora penetrate to within,
or far beyond, the northern boundary-line, and the same is true,
to a certain extent, of the moose and caribou (reindeer). The
more strictly southern forms are the opossum, raccoon, and pec-
cary, the last, however, not penetrating farther north than the

NEOTROPICAL REALM. 73

Red River, in Arkansas. The bison, which was at one time very
abundant on the western prairies, has now almost wholly disap-
peared, and impending destruction likewise threatens the prong-
horn (Antilocapra Americana), which in the furcation and shedding
of its horns may be considered to be the most divergent type of all
antelopes. Characteristic rodent forms of the prairies are the prairie-
dog (Cynomys Ludovicianus) and the gopher (Geomys bursarius).
More properly belonging to the eastern wooded sections are the
beaver (in the north), identical with the European species, the
skunk, and Canada porcupine.

6. The Rocky Mountain Sub-Region comprises the mountainous
tracts of the West-Central United States, and a similar region in
Canada extending to about the fifty-fifth parallel of latitude. Its
southern boundary is determined by the as yet not very exactly
defined Sonoran transition region. Its general and distinctive faunal
features have already been indicated.

7. The Californian Sub-Region is comprised within the border-
land which stretches along the Pacific west of the main mountain
axis, and extends northward to about the fiftieth parallel of latitude.
Many of its faunal features are borrowed from the Neotropical
realm, but in its entirety the fauna is distinctively North American.
Among its characteristic mammalian forms are the sewellel (Ha-
ploodon) and the grizzly bear (Ursus horribilis). Other distinctive
types are the California condor (Sarcorhamphus Californianus), the
ground cuckoos (Geococcyx), and the singular bird known as
Chamea. The number of humming-birds is greater than in the
Eastern United States.

THE NEOTROPICAL REALM.

This region, as usually recognised, comprises the continent of
South America, the West India Islands, Central America, and the
lowlands—tierras calientes—on either side of the Mexican plateau.
While, therefore, it is in the main clearly circumscribed by its
water-boundary, the northern portion, or that which borders on the
Holarctic, is much less sharply defined, as must invariably be the
case where two faunal regions overlap. The principal features of
the greater portion of this vast tract are singularly uniform. An
enormous expanse of forest, unequalled for its continuity and luxu-
riance of growth, occupies fully one-half of the surface area, cover-

4 GEOGRAPHICAL DISTRIBUTION.

ing not only the deep lowlands, but also the mountain-slopes to a
very considerable elevation. Commencing on the Atlantic border,
it stretches, through a north and south extent of thirty degrees of
latitude, almost unbroken for nearly three thousand miles to the
base of the Andes, harbouring in its dense recesses a host of the most
varied animal forms. Beyond, and partially enclosed within, the
limits of this vast forest region are the various forms of pasture-
land, or grassy plains, the llanos or savannas of Venezuela, the
campos of the highlands of Brazil, and the pampas of the Argen-
tine Republic and Patagonia. In the great Andean chain, which
traverses in one continuous sweep the entire north and south ex-
panse of the region, we have all the more characteristic features of
a mountain-system developed on a most gigantic scale—high pla-
teaus, deep valleys, wooded and barren slopes—conditions affecting
in a most marked degree the diversity of its animal and vegetable
creations. Desert areas, or such as are rendered almost unfit for
habitation by reason of extremes of climate, like the north of both
the North American and Eurasiatic continents, are, if we except
the most elevated mountain-summits, limited to a few scattered
patches of small area in the Argentine Republic, and to a narrow
tract of littoral lying in Peru and Chili, on the Pacific side of the
mountain-axis.

Zoological Characters of the Neotropical Realm.—In com-
paring the fauna of the Neotropical with that of the other zoogeo-
graphical regions we are struck with two things: 1, its extraordi-
nary richness; and 2, the very great preponderance of forms that are
peculiar to the region and not met with anywhere else. According
to Wallace, the region comprises no less than forty-five families and
nine hundred genera of vertebrate animals which are strictly pe-
culiar to it, while it has representatives of one hundred and sixty-
eight out of the total of about three hundred and thirty families
recognised by naturalists ; in other words, more than one-half of
all the families scattered over the globe are here represented. Of
about thirty-one mammalian families eight are almost completely
confined to the region, as follows: The Cebide, or true South
American monkeys; the Hapalidee, or marmosets; the Phyllosto-
mid, or simple leaf-nosed bats, which include the vampires (with
one extra-limital species in California); the Chinchillide, compris-
ing the chinchilla and vizeacha, a small group of animals confined

NEOTROPICAL MAMMALIA. 73

principally to the Alpine slopes of the Andean chain, in Peru, Bo-
livia, and Chili, but also (Lagostomus) inhabiting the lowland plains
of the Argentine Republic and Uruguay; the Caviide, the cavies
(Cavia) and agouties (Dasyprocta), a family of rodents to which the
guinea-pig belongs, and whose members range from Mexico to be-
yond the forty-eighth parallel of south latitude; the Bradypodida,
or sloths, confined exclusively to the forest region; the Dasypodide,
or armadillos, which are found throughout almost the entire region,
with one species (Dasypus peba) penetrating as far north as Texas;
and the Myrmecophagide, or ant-eaters. The Cebide, or South
American monkeys proper, constitute a very distinct group of quad-
rumanous animals (Platyrhina), distinguished from the monkeys of
the Old World (Catarhina) by several very prominent characters,
such as the broad nasal septum (whence the designation of flat-
nosed monkeys, Platyrhina), the absence of ischial callosities and
cheek-pouches, and the presence of an additional premolar tooth on

18
each side of each jaw, making the total dental formula ier 36, in-

16
stead of 17 82, as we find it in the Old World apes and man. In

the smaller group of the marmosets and lion-monkeys (Jacchus, Mi-
das) we find the same number of teeth as in the catarhines, but the re-
lation of the premolars to molars is reversed, 7. e., they are arranged
2—2 : 2—2
—m.; instead of pm. ——,
2 2—2

Mi. yiig’ In none of the American monkeys is the thumb com-

. 3—sd
according to the formula ieag BE bic ath

pletely opposable to the other fingers, an important distinguishing
character; and scarcely less important is the presence, in most cases,
of a prehensile tail, which, as such, is developed only in this group
of the Quadrumana. The range of the American monkeys, in
marked contrast to that of the African, is limited virtually to the
forest region, in which alone they find their proper sustenance.
Their most southern extension appears to be about the thirtieth
parallel of south latitude, and their most northern, the southern
portions of Mexico. No representatives of the order are met with
in any of the West India Islands, which are also wanting in all Car-
nivora and Edentata. The Platyrhina comprise, among other groups,
the well-known howling-monkeys (Mycetes), spider-monkeys (Ate-

76 GEOGRAPHICAL DISTRIBUTION.

les), and capuchins. The Neotropical Carnivora embrace a number
of larger and minor cats, the most formidable of which are the
jaguar and couguar (puma), the former ranging from the pampas
of the Argentine Republic to Texas, and the latter, as has already
been observed, from Patagonia to about the sixtieth parallel of north
latitude in Canada. Among the lesser animals of this family are the
jaguarundi, ocelot, and other so-called tiger-cats. Of the weasels,
there are no representatives of the genera Mustela or Putorius over
the greater part of the region. The Canide are represented by
various forms of wild-dogs (Icticyon, Lycalopex, Pseudalopex),
which are principally confined to the open grass-country; the wolf
and fox are both absent, except from certain portions of Mexico,
which ought, perhaps, more properly to be relegated to the inter-
mediate tract which separates this from the Holarctic region. The
only member of the Urside found in the entire continent of South
America (with Central America) is the “spectacled”’ bear (Ursus
ornatus), from the Chilian and Peruvian Andes, which, through
certain peculiarities of structure, has been separated by some au-
thors from the true bears (Ursus), and placed in a distinct group,
Tremarctos. Among the distinctive rodents, other than the cavies
and agouties, are the subungulate capybara and paca, and the
beaver-like coypu (Myopotamus). A negative feature is the almost
total absence of Insectivora. The hoofed animals (Ungulata) are
but very sparingly represented in the Neotropical realm, a circum-
stance in marked contrast to what is presented by the similarly-
situated Ethiopian or African region. The antelopes, so. char-
acteristic of the warmer parts of both the African and Asiatic
continents, are completely wanting, and there are likewise neither
indigenous horses, oxen, sheep, nor goats. A comparatively lim-
ited number of species of deer are scattered throughout the region,
from Mexico to the Rio Negro in Patagonia. Of other even-toed
ungulates (Artiodactyla) we have the peccaries (Dicotyles), the
American representatives of the Old World family of swine (Suide),
whose range extends to the Red River, in Arkansas, and conse-
quently considerably beyond the limits of the region; and the
llama, alpaca, guanaco, and vicufia, together constituting the genus
Auchenia, which are the New World representatives of the camel
family (Camelide). It is a most striking fact in the distribution
of this family of ruminants, that the only two genera of which it

FAUNA OF THE NEOTROPICAL REALM. ve

is composed should, in their habitats, be separated by one-half of
the circumference of the globe; and that, further, while the one
genus, Camelus, belongs strictly to the Northern Hemisphere, the
other, Auchenia, is restricted to the Southern. But these are not
the only peculiarities distinguishing this singularly discontinuous
family, for, while the Eastern representatives are specially adapted
to an existence in the hot and parched surfaces characteristic of
desert lands, those of the Western Hemisphere, on the contrary,
are habituated to the rugged and snow-covered slopes of the South
American Cordilleras.* The tapir, which, with the exception of
the peccary, is the only pachydermatous South American mammal,
presents us with an example of a discontinuous family no less
marked than that of the Camelidz. Its four to six members are,
with one exception, all confined to South and Central America, in-
habiting the lofty mountain regions of from eight to twelve thou-
sand feet elevation, as well as the lowland equatorial forests. The
only extra-limital representative of the family is the Tapirus Malay-
anus, or white-banded Malay tapir, whose home, the Malay Penin-
sula, Sumatra, and Borneo, is separated from that of its American
congener by an interval of nearly one-half the earth’s equatorial
circumference.

The bird-fauna of the Neotropical realm is no less striking by
its diversity than the mammalian. It comprises representatives of
upwards of six hundred and eighty genera of land-birds, of which
some five hundred and seventy, or just five-sixths of the entire num-
ber, are peculiar to it.*° The vernal migration naturally tends to
spread many of the South American avian types northward, and
thus a large number of even the more strictly Neotropical forms
have what might in a measure be considered North American or
Holarctic representatives. Of the humming-birds (Trochilide), a
distinctively South American family, comprising about one hundred
and twenty genera, and upwards of four hundred species, no less

* The vicuiia is rarely found at a lower level than thirteen thousand feet ;
the llama descends to three thousand. It has already been remarked, when
treating of the influence of climate upon distribution, that, while the camel is
more properly an animal of the warm country, it yet winters, with apparent
comfort, as far north as the region of Lake Baikal, in latitude 52° to 53°,
Again, while most suitably adapted to a desert region, the animal, it appears,
can conveniently accommodate itself also to rugged mountain-slopes.

78 GEOGRAPHICAL DISTRIBUTION.

than fifteen species are found within the limits of the Holarctic
realm and the Sonoran transition tract, one species, the ruby-throat
(Trochilus colubris), on the east coast of the continent of North
America extending its range northward beyond the Canadian bor-
der, and one (Selasphorus rufus) on the west as far north as Sitka.
So, again, the Conurine, or macaws, an equally distinctive Neo-
tropical group, with about eighty species, have a sclitary Holarctic
representative in the Carolina parakeet (Conurus Carolinensis),
whose range, at the present time, seems not to extend much farther
than the State of South Carolina, but which, until a comparatively
recent time, penetrated as far north as Nebraska. The Cerebide,
or sugar-birds, whose brilliancy of plumage rivals that of the hum-
mers, have an outlying member in Certhiola Bahamensis, of which
a colony has been established on one of the Florida Keys, or just
beyond the limits of the Neotropical realm.*’ Other characteristic
families of South American birds are the toucans and aracaries
(Rhamphastide), a strictly frugivorous group, recalling by the
structure of the bill the distant Old World horn-bills; the jaca-
mars (Galbulide); the saw-bills, or motmots (Prionitide) ; the
Pipride, or manakins; the Cotingide, or chatterers, which in-
clude, besides the cotingas and pompadours, the famous cock-of-
the-rock (Rupicola), umbrella-bird (Cephalopterus), and bell-bird
(Chasmorhynchus); the Dendrocolaptide, or tree-creepers, with
upwards of two hundred species; the wonderfully variegated tana-
gers (Tanagridi), with upwards of three hundred species, which
may in a measure be considered to occupy the place of the Tem-
perate Zone finches and sparrows, and of which the common scarlet
tanager (Pyranga rubra) and summer-redbird (Pyranga estiva)
are familiar North American examples; to the same group belong
the South American spice-birds of the genus Calliste, and the or-
ganist (Euphonia); the Cracide, curassows and guans, which are
the largest game-birds of the region, and which take the place of
the Old World grouse and pheasants; and the Tinamidz, or tina-
mous, a group of birds recalling in their general appearance the
partridges, and possessing certain affinities with the ostriches. The
exquisitely decorated trogons (Trogonidé) present us with one of
the most remarkable instances of a discontinuous family, whose
representatives are found at opposite points of the earth’s equatorial
circumference—the Neotropical and Oriental regions. The inter-

FAUNA OF THE NEOTROPICAL REALM. dic)

vening continent of Africa appears to be almost entirely deficient
in the members of this family. The Struthionide, or ostriches, are
similarly divided, the South American continent possessing three
(of the genus Rhea) out of the five or six species of which the
family is composed. The noble and ignoble birds of prey are both
well represented in the Neotropical realm, and it is here that the
most powerful and largest bird of flight, the Condor (Sarcorham-
phus gryphus), is to be found. ‘True eagles of the sub-family
Aquiline are absent from the greater part of the region, and there
are no representatives of the common genera distinctive of the
Temperate Zone—Aquila, Haliaétus (the bald eagle), or Chrysaétos
(the golden eagle). The harpy eagle (Thrasaétus harpya), more
properly a buzzard, penetrates as far north as the Texan frontier.
Among the characteristic families of birds which the Neotropical
region shares with the western division of the Holarctic are the
Tyrannide, or tyrant-shrikes, the New World representatives of
the Old World fly-catchers (Muscicapide), and the Icteride, or
hang-nests, the New World representatives of the Old World
starlings (Sturnid), of which the common Baltimore oriole and
the cassique (Cassicus cristatus) are familiar examples. It is a
singular fact that the crows and ravens (Corvus), which are
otherwise nearly cosmopolitan, and which comprise upwards
of fifty species, are completely wanting in the greater part of
the Neotropical realm, no species being found south of Guate-
mala.

The Neotropical reptile-fauna is scarcely less well-marked than
the mammalian or the avian. It includes the giant boas and ana-
condas of the genera Boa, Epicrates, and Eunectes, the coral-snake
(Elaps), which has one or two extra-limital representatives in the
United States, the venomous crotaloids, with the true rattlesnakes,
Lachesis, and Craspedocephalus (jararaca), both alligators (cayman)
and crocodiles, and no less than about one hundred and fifty species
of the singular lizards constituting the family Iguanide. The ano-
lids and amphisbeenians are represented by numerous species. The
tailed amphibians, such as the newts and salamanders, are almost
absent, but in their place there is an unusual development of the
tailless forms, the toads and frogs (horned-frog, Ceratophrys; Hemi-
phractus), especially of the tree-frogs (Hylide).—The fresh-water
fishes of the Neotropical realm are specifically more numerous than

80 GEOGRAPHICAL DISTRIBUTION.

those of any other region, with perhaps the exception of the Hol-
arctic. According to Ginther they comprise nearly seven hundred
distinct forms, although representing only nine families. About
one-third of the species belong to the family Characinide, and
a somewhat larger number to the cat-fishes (Siluride). The
toothed-carps (cyprinodonts) are represented by sixty or more
species. Among the distinctive fishes of the region are the
electric eel (Gymnotus electricus), from the equatorial regions,
and the remarkable lung-fish (Lepidosiren paradoxa) of the Ama-
zon.

The Neotropical tract may be conveniently divided into the
following sub-regions: 1, the Brazilian, comprising Brazil, Guiana,
Venezuela, Colombia, Ecuador, Paraguay, and the cis-Andean por-
tions of Peru and Bolivia, inclusive of the eastern slope of the
mountain-axis, essentially a region of dense and luxuriant forests;
2, the Chilian, principally a region of open plains and pampas,
comprising Chili, Patagonia, the Argentine Republic, Uruguay,
and the remaining parts of Peru and Bolivia, extending to about
the fourth parallel of south latitude; 3, the Mezican, including
the Isthmus of Panama, Central America, and Southern Mexico ;
and, 4, the Antillean, or the sub-region of the West India Isl-
ands. In the first of these sub-regions, the Brazilian, the faunal
facies is essentially that of the Neotropical realm taken as a whole,
inasmuch as there is scarcely a single group of important or typical
South American animals which has not its representatives here.
Furthermore, the majority of these forms have their greatest de-
velopment in this tract. Among its most distinctive negative
elements may be cited the chinchillas, the spectacled bear, the
llamas (with the alpaca, vicufia, and guanaco), the rheas (South
American ostriches), and the condor—members of the fauna of
the Chilian sub-region—which are either wholly wanting, or but
barely pass beyond the regional confines. Positive distinguishing
characters among the Mammalia may be found in the special de-
velopment of the quadrumanous and edentate types—among the
former, in addition to the more widely distributed forms, such as
Cebus, Ateles (spider-monkey), and Mycetes (howler), the woolly-
monkeys (Lagothrix), the sakis (Pithecia), the douroucoulis or
night-monkeys (Nyctipithecus), squirrel-monkeys (Chrysothrix), and
some thirty or more species of marmosets, which appear to be con-

FAUNA OF THE NEOTROPICAL REALM. 81

fined to the tropical forests; and among the latter, several species
of armadillo, the great ant-eater (Myrmecophaga jubata), and the
various forms of two-toed (Choleepus) and three-toed (Bradypus)
sloths—the spiny-rats (Echimyidz), most of whose representatives
are confined to this region, and the manatee or vacca marina (Ma-
natus), which ascends the river Amazon. Among the more re-
stricted birds are the capitos, the trumpeter (Psophia), screamer
(Palamedea), hoazin (Opisthocomus), pauxi, and boat-bill (Can-
croma).

The fauna of the Mexican or Central American sub-region corre-
sponds closely with that of the sub-region just described, from which
it differs mainly by the comparative paucity of its developed types,
and by the more pronounced infusion of the Holarctic or northern
element. As representatives of the latter we have the shrews, the
hare (one species also in Brazil), ground-squirrel, fox, and Bassaris.
The very limited number of distinctive types include the Central
American tapir (Elasmognathus Bairdii), Myxomys among the
mice, and Heteromys among the pouched-rats.—The Chilian fauna,
some of whose more prominent features have already been indi-
cated, is broadly distinguished from the faunas of the north by its
negative characters, as well as by the few distinctive types which
more or less belong to it—llama, alpaca, vicufia, guanaco, spectacled
bear (Tremarctos ornatus), Patagonian cavy (Dolichotis), coypu
(Myopotamus coypu), chinchilla, viscacha (Lagostomus), Chlamy-
dophorus (among the armadillos), and several peculiar genera of
mice and the rat-like octodonts. The puma, deer, and skunk ex-
tend their range to the Strait of Magellan, and the wolf-like dogs
of the genus Pseudalopex, the guanaco, and several mice (Reithro-
don, Hesperomys) into Tierra del Fuego. The monkeys, tapirs,
peccaries, and sloths are wanting.—With respect to its mamma-
lian-fauna the Antillean sub-region, as might be expected, pre-
sents the most negative features. There are neither carnivores,
monkeys, nor edentates, the only orders represented being the bats,
rodents (Capromys, Hesperomys), and insectivores. The last are
represented by two species of the genus Solenodon, whose nearest
allies are the Centetide of Madagascar. An agouti inhabits some
of the islands of the Lesser Antilles (St. Vincent, Sta. Lucia). The
resident land-birds are comprised in about one hundred genera and
upwards see hundred species, about one-third of the former and

82 GEOGRAPHICAL DISTRIBUTION.

nearly nine-tenths of the latter being peculiar. The remaining
species are South American or Central American forms. In addi-
tion to this number there are some ninety or more migrants from
North America.

THE ETHIOPIAN REALM.

Next in importance to the Neotropical realm in the number,
variety, and peculiarity of its animal productions, is the Ethio-
pian, or African. This region comprises the entire continent of
Africa south of the Tropic of Cancer, and likewise that portion of
Arabia which lies to the south of the same line; the Island of Mada-
gascar, with some neighbouring groups of smaller islands, is also
included. By some naturalists the northern boundary is extended
as far north as the Atlas Mountains, thus including the entire Desert
of Sahara. With the limitation first assigned almost the entire
region lies within the tropics, and is thus the most strictly tropical
of the faunal regions. In its physical features it presents several
well-marked peculiarities. In the ‘first place, we have the vast
expanse of desert, which in the north occupies a transverse band
varying in width from about four to nearly ten degrees of latitude.
This is succeeded by what may not improperly be termed the open
pasture-lands, which, as a narrow belt bounds the Sahara on the
south, curves southwards at about the position of Kordofan, and
occupies the greater portion of the continent lying east of the thir-
tieth parallel of east longitude and south of the fifth parallel of south
latitude, A very considerable portion of this pasture tract forms
a plateau of from four thousand to five thousand feet elevation.
Included within it, and bounded on the west by the Atlantic Ocean,
is the region of the great equatorial forests, to the present day a
terra incognita in great part to both geographers and naturalists.
That portion of the African continent lying south of the Tropic of
Capricorn differs in many respects, both as to its physical con-
figuration and its vegetable products, from the region to the north-
ward, and is characterised by a vegetation which is at the same
time one of the richest and most remarkable on the globe. With
this marked peculiarity in its vegetable development there is of
necessity a certain amount of faunal peculiarity superadded as well,
but this is not sufficiently pronounced to permit of a separation of
this tract from the tract lying immediately to the north. We have

ETHIOPIAN MAMMALIA. 83

thus on the continent three strictly-defined faunal sub-regions : 1,
the pasture-lands already described, constituting the Last-Central
African sub-region, through whose vast expanse there is manifest a
strong identity in the character of the animal products, the same
or very closely related animal forms being in many instances found
at the extreme points of the region; 2, the forest tract, constitut-
ing the West African sub-region, whose animal products naturally
differ very essentially from those of the last; and, 3, the desert
or Saharan sub-region, containing a comparatively limited fauna,
which, with almost insensible gradations, merges into the fauna of
the Mediterranean transition tract. To the same division belong
in great measure the desert tracts of Arabia, or that portion of the
peninsula lying to the south of the Tropic of Cancer. The Island
of Madagasczr, with Mauritius, the Seychelles, &c., forms an in-
dependent sub-region of its own.

Zoological Characters of the Ethiopian Realm.—The mam-
malian-fauna of the Ethiopian region is characterised no less by
the remarkable development of its carnivore and hoofed animals
(Ungulata) than by the peculiarities presented in its quadrumanous
types. Of the hoofed animals there are two families which are
absolutely restricted to the region: the Hippopotamide, or hip-
popotami, and the Camelopardide, the giraffes. The former com-
prise two species, the common hippopotamus (H. amphibius), which
is found in nearly all the larger African rivers from the Cape to
the Sahara, and from the Zambesi to the Senegal, and the smaller
Liberian hippopotamus (Cheropsis Liberiensis), from the river St.
Paul on the west coast, characterised by the possession of only one
pair of incisors instead of the normal two pairs.* The latter in-
cludes but a single species, the well-known giraffe (Camelopardalis
giraffa), which ranges throughout the greater portion of the African
open country, and to a certain extent also invades the forest region.
As to the pigs (Suid), a family very closely related to the Hippo-
potami, the Ethiopian region is deficient in the genus Sus, which

* In antiquity the hippopotamus appears to have been very abundant in
the waters of the Nile as far down as Lower Egypt. Even as late as 1600
hippopotami were trapped at Damietta, situated at the mouth of one of the
arms of the Nile, and in the early part of this century they were still ob-
served by Rippell in Nubia. At present they are found in the Nile only in
its upper course.

84 GEOGRAPHICAL DISTRIBUTION.

comprises the common hog or wild-boar of Eurasia, but its place
is taken by the so-called ‘‘ water-hogs” and ‘‘ wart-hogs,” of the
genera Potamocherus and Phacocheerus. Of the Rhinocerotide, a
family which this region shares with the Oriental or Indian, there
are four or five species or varieties, all of them two-horned. By far
the most important of all the African ungulates are the ruminants.
We have here an extraordinary development of the antelopes, which
in the number of their species far surpass those of all the other
regions put together. No less than from eighty to ninety distinct
species have already been described, and doubtless many more re-
main in the districts that have not yet been explored. Among the
numerous genera of these animals, which comprise forms ranging in
size from the dimensions of a large ox (eland) to those of a rabbit
(m’doqua, guevi), there are none that are found in any other faunal
region, excepting Gazella, the gazelle, and Oryx, to which the gems-
bok belongs, the former represented by a limited number of species
in the desert regions of Western and Southwestern Asia (Arabia,
Persia), and the latter, by a single species, also from the Arabian
desert. The antelopes may be conveniently divided by their habits
into four groups: 1. The desert antelopes, or such as frequent the
desert regions, like the gazelle; 2. The bush antelopes, or those
which habitually frequent the forest recesses, like the koodoos,
water-bucks, and bushboks; 3. The rock antelopes, which, like the
klipspringer, recalling in aspect and habits the European chamois,
frequent the mountain-fastnesses ; and, 4. The antelopes of the
open plains—gemsbok, blessbok, hartebeest, gnu, springbok —
which comprise the greater number of species, and which, as the
springbok, not unfrequently congregate in herds of several hundreds
or even thousands. The more familiar forms of ruminants, such as the
deer, sheep, and goats, are, with the exception of an ibex found in the
Abyssinian highlands, completely absent. The only deer-like animal
found on the African continent south of the Sahara is the chevrotain
(Hysemoschus aquaticus), from the region lying between the Senegal
and the Gaboon, a small animal closely allied to the Oriental musk-
deer, whose nearest representatives, the Traguli, inhabit the south-
eastern extremity of the continent of Asia, and the adjacent islands of
the East Indian Archipelago. The wild-ox (Bos) is also absent, but
its place is occupied by the Cape buffalo (Bubalus Caffer), whose
domain extends throughout the greater portion of South, Central,

ETHIOPIAN MAMMALIA. 85

and Western Africa. Characteristic non-ruminating ungulates are
the zebras and quaggas (Equus zebra, Burchellii, Grevyi, and
quagea), and the Abyssinian wild-ass (Equus texniopus), by many
naturalists supposed to be the progenitor of the domestic animal.
Among the beasts of prey (Carnivora) there are the lion (possibly
two species), leopard, panther, the spotted, striped, and brown
hyenas, jackal, and the aard-wolf (Proteles), an animal in many
respects intermediate between the dog and hyena, and constitut-
ing the type of a distinct family (Protelide), which is peculiar to
the region. The tiger is absent, as it is, in fact, from the entire
continent of Africa. The wolf and fox are also both wanting;
but the latter is replaced in the Saharan and adjoining districts
by the closely-related fenneec (Fennecus). There is a remarkable
development of the civets (Viverride), with a host of genera that
are peculiar to the continent; the best known among these are
the civets proper (Viverra), genets (Genetta), and the ichneumon
(Herpestes), all of which, however, are found also beyond the
limits of the region. Bears are entirely wanting, the only Afri-
can representative of the Urside (Ursus Crowtheri) being extra-
limital, a native of the Atlas Mountains. The Ethiopian Quadru-
mana, or apes, constitute a part of the Old World group of the
Catarhina, distinguished from the monkeys of the New World, as
has already been stated in treating of the Neotropical realm, by
the comparative narrowness of the nasal septum, the presence, in
most cases, of ischial callosities and cheek-pouches, the universal
absence of a prehensile tail, and the number of teeth, which never
exceed the normal. number (thirty-two) characteristic of the human
species. This group comprises the most perfectly organised, or
most hominine of the quadrumanous species, and, at the same time,
those in which the fiercest and most savage disposition is combined
with a less advanced structural development. As representatives
of the former we have the anthropoid or man-like apes, constituting
the family Simiade, which, in the African continent, comprises the
chimpanzees and gorillas, and, in Asia and Malaysia, the gibbons
and orang-outangs. The two species of chimpanzee (Troglodytes
niger and T. calvus), as well as the gorilla (T. gorilla), are both re-
stricted to the forest region of Equatorial Africa, especially the
west coast; but it is still a matter of considerable uncertainty how
far inland their range may extend. The researches of von Heuglin,

86 GEOGRAPHICAL DISTRIBUTION.

Schweinfurth, and more recent travellers, seem to show, almost
beyond doubt, that the gorilla, which until recently was consid-
ered to be limited in its haunts to the west-coast region—the forest
tracts lying between about ten degrees of north latitude and the
Gaboon River, including the Crystal Mountains—is in reality also
an inhabitant of the deep interior of the continent, frequenting the
forest recesses which bound the western tributaries of the Nile.
Lower in the scale of organisation, but scarcely inferior in size in
many cases to the anthropoid apes, are the dog-faced monkeys,
constituting the family Cynopithecide. These, which embrace
many of the most savage forms of all the monkey tribe, inhabit
the greater portion ot the Ethiopian region, the forests as well
as the open plains and rocky fastnesses of mountain solitudes.
Among the better known and more formidable members of this
extensive family, which is also well represented in the Oriental
region (macaques), and less numerously in the Austro-Malaysian
(the islands of Batchian and Timor) and Tyrrhenian (the Barbary
ape of the Rock of Gibraltar) transition regions, are the baboons,
mandrills, chacmas, Diana monkeys, and mangabeys, the first three
being characterised by a prolonged snout, similar to that of the
dog, at the extremity of which are situated the nostrils; the tail is
rudimentary, or almost completely wanting. The Colobi constitute
another extensive group of African apes. True monkeys, as well
as the more distinctive of the African Mammalia—such as the lion,
leopard, hyena, zebra, antelopes, giraffe, hippopotamus, and rhi-
noceros—are wholly wanting in the Island of Madagascar, whose
principal mammalian feature is constituted by the lemurs (Lemur-
ide), or half-monkeys, a group of animals usually considered to
form a sub-order of the Quadrumana, in certain peculiarities of
structure closely approximating the most ancient progenitors of the
ungulates. The presence of lemurs on the Island of Madagascar,
the continent of Africa, and Southern India (with Ceylon), has led
some naturalists to the conclusion that at one time direct land
connection existed between the several regions, an assumption
that is by some naturalists considered to be further borne out by
other equally well-marked faunal characteristics. To this supposed
formerly-existing land-mass of the Indian Ocean, which, if it ever
existed, may or may not be represented in part by the sunken
“Chagos Banks,” and the outlying islands, such as the Seychelles,

FAUNA OF THE ETHIOPIAN REALM. 87

Laccadives, and Maldives, the name of ‘‘ Lemuria” has been given.*
A very remarkable quadrumanous animal of the Island of Mada-
gascar, and the only representative of its family, is the aye-aye
(Cheiromys Madagascariensis), formerly described as a squirrel,
which has many points of relationship with the rodents. The only
other orders of Ethiopian Mammalia that need be specially referred
to are the Proboscidea and the Edentata, the former represented
by the African elephant (Loxodon Africanus), and the latter by
the scaly ant-eaters (Manis, Pangolin), and the curious animals
known as aard-varks (Orycteropus). The members of the genus
Hyrax, which includes the shaphan or coney of the Bible, animals
in several characters allied to the rodent on the one side, and the
rhinoceroses, among pachyderms, on the other, constitute, in the
opinion of many naturalists, a distinct order, Hyracoidea, apart
by itself. Several species (Hyrax, Dendrohyrax) are recognised, all
of about the size of the rabbit, and, with one exception, the coney,
which is also found in Syria and Palestine, restricted to the African
continent.

The bird-fauna of the Ethiopian realm is by no means as rich,
either in the actual number of its forms or in those that are pecu-
liar, as the Neotropical. Neither do we find, as a rule, that brill-
iancy and variety in the plumage which distinguish the birds of the
South American continent, although gaudily-coloured birds are not
exactly rare. Among these are the Irisoride, a group of birds
allied to the hoopoes, and remarkable for their metallic hues; the
Meropide, or bee-eaters, of which the common bee-eater of South-
ern Europe (Merops apiaster) is a well-known representative; and
the curious forest-loving birds, known as the turacos and plantain-
eaters (Corythaix, Musophaga), in a measure related to the South
American toucans, constituting the family Musophagide. The
Ethiopian region is the home, par excellence, of the insectivorous
honey-suckers (Nectarinide +t), a family of birds bearing a super-
ficial resemblance to the American hummers, which they also, in
many cases, rival in the brilliancy of their plumage. The honey-
guides (Indicatoridz), formerly classed as cuckoos, and to an extent

* Tt is here that, by some anthropologists, has been located the most an-
cient abode of man.
+ Also abundantly represented in the Australian and Oriental regions.

88 GEOGRAPHICAL DISTRIBUTION.

partaking of their habits, but probably more closely related to the
woodpeckers, are found in almost all parts of the region. The
fly-catchers, warblers (Sylviade), true finches (Fringillide), and
weaver-birds (Ploceide) are numerically well represented, more
especially the last, of whose two hundred and fifty, or more, species
about two hundred are found within the limits of this region. This
family comprises, among other birds, the small speckled and red-
billed finches, known as the estrilds and amadines, the tailor-bird
(Textor), the true weavers (Ploceus and Symplectes), and the long-
tailed whydahs (Vidua), from the west coast. The parrots are but
feebly represented in the Ethiopian region, the macaws and cocka-
toos (Conurine and Cacatuide) being wholly wanting. With very
few exceptions—Paleornis—all the African parrots belong to the
group of the Psittacini, of which the common grey parrot (Psittacus
erithacus) is a familiar example. No species is found to the north
of the fifteenth parallel of north latitude. Of the gallinaceous birds
there is a marked representation of the grouse tribe, especially of the
genus Francolinus, and among the pheasants we have all the species
of guinea-fowls (Numidine), whose nearest allies appear to be the
American turkeys. Birds of prey are very abundant, comprising,
in addition to the common forms of vultures, eagles, &c., the hawk-
like bird known as the “secretary” (Serpentarius), a near ally of
the South American cariama. Finally, the Ethiopian region pos-
sesses, although not exclusively, the ostriches (Struthio camelus,
the common form, and 8. molybdophanes, from the Somali ter-
ritory), of the family Struthionide.

The reptile-fauna is very rich and varied, and comprises a con-
siderable number of peculiar forms. Of Ophidia we have a large
development of the vipers (Viperide), and among these one of the
deadliest of venomous serpents, the puff-adder (Clotho). Of the
larger constrictors, the rock-snake (Hortulia) and Seba’s python
represent the Pythonide. The lizards comprise, among other sin-
gular forms, the Agama, the typical Old World representative of
the American iguanas, and the chameleon, with its distinctive
changing hues. Crocodiles are met with in nearly all the larger
streams.

The fresh-water fishes of the African realm are limited, accord-
ing to Giinther, to somewhat more than two hundred and fifty
species, representing fifteen distinct families or groups. About

FAUNA OF THE ETHIOPIAN REALM. 89

sixty of these are siluroids (cat-fishes), fifty cyprinoids (carps), and
about an equal number members of the family Mormyride. Owing
to the broad distribution of the different types, which are spread
throughout the greater extent of the continent, a division of the
region into ichthyic sub-regions is rendered impossible. Of some
fifty-six species found in the waters of the Upper Nile, no less than
twenty-five are absolutely identical with forms belonging to the
West African rivers, and doubtless most of these also occur in the
waters of the unexplored tracts of the interior. Greater dissimi-
larity exists between the northern and western faunas and those of
the south, where the relationship has been rendered generic instead
of specific. Thus, the fishes of Lake Nyassa and the Zambesi River
are specifically distinct from those of the great equatorial lakes,
and their outflowing northern and western waters. Africa has rep-
resentatives of two genera of ganoid proper, Polypterus and Cala-
moichthys, and one genus of lung-fishes, Protopterus (P. annectens),
the last closely related to the Lepidosiren of South America. With
the fish-fauna of this region the Ethiopian agrees in the partial
possession of the characinids (about thirty-five species) and the
chromids, and the genus Pimelodus among the cat-fishes. How
the transference of similar or identical types was effected to such
widely remote areas, whether through the intermedium of the
waters of a continental tract now submerged beneath the Atlantic,
or by way of the northern streams, it is impossible to say.

The Ethiopian faunas, taken collectively, exhibit a remarkable
homogeneousness throughout, so that the delimitation of even the
three greater faunal sub-regions becomes difficult. The East Central
African sub-region is, strictly speaking, representative of the entire
tract, where the vast majority of all the distinctive types are found.
The West African sub-region is more properly the home of the
anthropoid apes, the chimpanzee and gorilla, and of the numerous
species of Cercopithecus and Colobus. The antelopes are much
less abundantly represented than in the plateau districts, although
they comprise a number of peculiar types, especially of the bush-
boks (Cephalophus). Other characteristic ungulates are the za-
moose, a species of buffalo (Bubalus brachyceros—possibly also found
in Abyssinia), the Hyzmoschus aquaticus, and the Cheropsis Li-
beriensis (hippopotamus). The insectivores present as a distinctive
type the otter-like Potamogale velox; the rodents the singular

90 GEOGRAPHICAL DISTRIBUTION.

Anomalurus, recalling the flying-squirrels ; and the edentates a
distinct species or variety of aard-vark (Orycteropus Senegalensis).

In the Saharan Desert tracts, where the necessary conditions for
existence are largely wanting, there is a marked impoverishment
of the fauna. The more formidable carnivores, such as the lion
and leopard, are absent from most districts, leaving their places to
be filled by some minor cats, the hyena, jackal, fox, and fennee.
The hoofed animals are represented (in some parts) by the buffalo,
and a limited number of antelopes (Gazella, Oryx, Addax). Among
rodents the families of rats and jumping-mice (Dipus, Scirtetes)
are fairly represented, in addition to which we have the porcupine
and hare (Lepus Mediterraneus). The ostrich is sufficiently abun-
dant throughout most of the region. Among the desert reptilian
forms may be mentioned the monitors (Varanide), scinks, sand-
lizards (Sepide), and agamas.

The deficiencies in the Madagascar mammalian-fauna have al-
ready been indicated. As representative types we have, in addition
to the lemurs and aye-aye, several civets (Galidia, Galictis), the
singular cat-like carnivore known as Cryptoprocta (C. ferox), a
water-hog (Potamocheerus), a sub-fossil species of hippopotamus,
and the native hedgehogs (Centetidz). The bird-fauna is made up
largely of Asiatic and African types, although peculiar forms are
abundant. Many of the reptilian forms, as the ophidian genera
Heterodon, Herpetodryas, Philodryas, have American representa-
tives.

ORIENTAL REALM.

This region comprises all that portion of the Asiatic continent
which is not included in the Holarctic and Tyrrhenian tracts (ex-
cepting the southern portion of the Peninsula of Arabia, which is
Ethiopian), the Island of Ceylon, Formosa, the Philippines, Suma-
tra, Java, and Borneo, besides some minor island groups. Within
its limits are, therefore, included the whole of extra-Himalayan
Hindostan, Farther India, the Malay Peninsula, ard that portion of
China lying south of the Nanling range. A very considerable part
of this region is covered with the most luxuriant forest growth,
which extends even to an elevation of from eight to ten thousand
feet along the slopes of the Himalaya, This forest character more
particularly distinguishes the Indo-Chinese and Indo-Malayan sub-

INDIAN MAMMALIA. 91

regions, the former of which includes Burmah, Siam, Anam, South-
ern China, the southern Himalaya slopes, and the luxuriant tracts
lying along the base of these mountains, known as the “ Terai”;
and the latter, the Malay Peninsula, with the Indo-Malaysian islands
already mentioned. A third sub-region, the Indian, is constituted
by the Indian Peninsula, exclusive of the Carnatic. The surface
here consists largely of open pasture or grass lands, the funda-
ment being in great part the alluvium of the existing rivers. In
the northwestern part, bounded by and partly lying within the
valley of the Indus, is the Indian Desert, where we encounter a
considerable intermixture of strictly Indian, Holarctic, and Ethio-
pian animal types. An essentially forest character again distin-
guishes the southern extremity of the Indian Peninsula—the Car-
natic—and the Island of Ceylon, which together form the fourth
sub-region, the Cingalese.

Zoological Characters of the Oriental Region. — A cursory
examination of the Oriental mammalian fauna shows it to be largely
made up of characteristic African forms, for which reason, indeed,
some naturalists have been induced to unite this region, either in
whole or in great part, with the Ethiopian. We have here the same
extraordinary development of the quadrumanous, carnivore, and
ungulate types, although in respect of these last very material differ-
ences present themselves which are sufficiently distinctive of the two
regions. Thus, in the Oriental region there are no representatives
of either the Camelopardelide or Hippopotamide, families peculiar
to the African continent; and the only member of the Equide—the
horses, asses, and zebras—the onager (Equus onager), is found in
the debatable land along the Indus, which unites the Oriental and
Holarctic tracts. There is also a great falling off in the number
of antelopes, of which there are scarcely more than a half-dozen
species—comprising among others the gazelle, the true antelope,
and nylghau ; but their place is in great measure taken by the
solid-horned ruminants, the deer, which, as has been seen, are
completely wanting in the Ethiopian region, but have here no less
than about twenty species, ranging in size from the diminutive
muntjac (Cervulus) to the giant rusa. This is also the home of
the beautiful axis. The cievrotains or mouse-deer (Tragulide), a
small group of diminutive deer-like animals characterised by the
presence of tusks in the upper jaw, have but one extra-limital

92 GEOGRAPHICAL DISTRIBUTION.

representative, the Hyzmoschus, from Western Africa, already re-
ferred to. Of the oxen we have the Indian buffalo (Bubalus Indicus
or buffelus), whose range at the present day (as a domestic animal)
comprises, in addition to its native haunts, a considerable part of
Northern Africa and Southern Europe (Hungary, Greece, Italy),
and three or four species of wild cattle—the gaour, gayal (Bibos)—
distributed over the greater portion of the region, from Java to the
Indian Peninsula. The sacred cow or Brahmin bull, commonly
known as the zebu, is now found only in a domesticated state.
The goats have but a single representative in the entire region—in
the Neilgherry hills; the sheep are completely wanting. The thick-
skinned ungulates are represented by four or five species of rhi-
noceros, both one- and two-horned, whose most eastward abode
appears to be the Island of Java; a solitary species of the South
American family of tapirs (Tapirus Malayanus), and about six
species of swine (Suid). Of the Carnivora there is, as in the
Ethiopian region, a large development of the civet-cats (Viverridz),
most of the genera representing the family in this region being pe-
culiar to it (Viverricula, Paradoxurus, Arctogale, Cynogale). The
Mustelidse comprise several well-known Holarctic forms, such
as the true weasel (Mustela), martin (Martes), otter (Lutra), and
badger (Meles), the last found only in Southern China. The cats
(Felidz) are represented by many of the more prominent types of
the Ethiopian region—such as the lion, leopard, and panther—in
addition to which we have the ounce and tiger, the latter extend-
ing its range as far north as the fifty-third parallel of latitude
(Lake Baikal), and westward to the borders of the Caspian Sea.
It is found in the islands of Java, Sumatra, Bali, and Saghalien,
but is absent from both Ceylon and Borneo. The dogs (Canide)
differ in several respects from the representatives of the same
group of animals entering into the Ethiopian fauna, and are more
nearly allied to the Holarctic forms. The true wolf is absent; but
its place is filled by several races of closely-allied wild-dogs, which
hunt wolf-like in packs over certain portions of the region, and
the jackal. The fox is represented by several species. Only one
of the three recognised species of hyena, the striped hyena (Hyena
striata), whose range embraces the entire northern part of the con-
tinent of Africa and a considerable portion of Western Asia, en-
. ters into the region. One primary distinguishing feature separating

INDIAN MAMMALIA. 93

the carnivore-fauna of the Oriental region from that of the Ethio-
pian is the presence in the former of bears, which comprise here
not only the singular forms _known as the sun-bears (Helarctos),
confined to the Indo-Malayan sub-region, and the honey-bears (Me-
lursus), whose range extends from the Ganges to Ceylon, but also the
true bears of the genus Ursus. The Indian elephant inhabits nearly
all the wooded tracts from the Himalaya slopes to Ceylon, and east-
ward to Borneo and Sumatra.* The Oriental region is, par eacel-
lence, the headquarters of the true mice and squirrels, there being
no less than about fifty specific representatives to each of the genera
Mus and Sciurus, or about one-half the number of all the forms
that have been ascribed to these genera. Both the round- and flat-
tailed flying squirrels (Pteromys, Sciuropterus) are distributed
throughout the region, the former, with the exception of three or
four extra-limital species found in Japan, being restricted to it,
and the latter distributed throughout a considerable portion of
the Holarctic region, and on both sides of the Atlantic. The
marmot is found in the debatable lands of the Western Himalayas,
at heights exceeding eight thousand feet. The bats have a much
more extended development in this region than in any other, except
the Neotropical, there being upwards of one hundred distinct spe-
cific representatives. These include members of all the generally
recognised families except the Phyllostomide, or simple leaf-nosed
bats (to which the South American vampyres belong), and conse-
quently embrace the short- and long-eared bats, the horse-shoe bats,
and the fruit-eating bats (Pteropide), commonly known as flying-
foxes. The most important of the Oriental Quadrumana are the
macaques (Macacus), to which the Barbary ape of the Rock of Gib-
raltar belongs, and which inhabit the entire region, and the long-
tailed Semnopithecus, which has nearly the same range, and several
of whose representatives inhabit the more elevated forests, even
during the winter, at heights exceeding eleven thousand feet. To
this genus belongs the peculiar Bornean ‘‘ nose-monkey” (S. nasa-
lis). The anthropoid apes are confined to the southeastern portion
of the region, and principally to the larger islands of the Malay

* The Javanese elephants do not appear to be indigenous to the Island of
Java. The Sumatra elephant, which was considered by Professor Schlegel to
represent a distinct species apart from the Indian (Elephas Sumatrensis), is
now usually referred to the latter species.

94 GEOGRAPHICAL DISTRIBUTION.

Archipelago. They comprise one or two species of Orang (Borneo
and Sumatra), the long-armed gibbons (Hylobates), whose range
extends from Java to Assam and China, and the siamang, a native
of Sumatra and the Malay Peninsula. The half-monkeys, or
lemurs (Nycticebus, Stenops), which were found to be so charac-
teristic of the Madagascar fauna, show a very great diminution in
numbers in the Oriental region. Their most distinctive or anom-
alous type is the tarsicr or spectrum lemur (Tarsius spectrum),
an inhabitant of Sumatra, Borneo, and Celebes (Austro-Malaysian),
which of itself constitutes a distinct family (Tarsiide). In the
structure of its feet—the extraordinary and unequal development
of the toes—and in several other peculiarities it is closely related
to the aye-aye, from which to the true lemurs it appears to form a
passage. Until recently classed with the lemurs, but now con-
sidered as representing the type of a distinct family of insectivorous
animals, are the cat-monkeys or flying-lemurs (Galeopithecus),
which inhabit the larger islands of the Malay Archipelago and the
Philippines.

The bird-fauna of the Oriental region is exceedingly rich and
varied, and, as might have been expected from its position, com-
prises in its assemblage a very large proportion of Holarctic, Ethio-
pian, and Australian forms. But the number of distinctive forms
are sufficiently numerous, and eminently serve to characterise the
region. Among these are the laughing or babbling thrushes (Timal-
idx), a family which, though not absolutely restricted to the
region, has its headquarters there. Nearly two hundred of the
two hundred and fifty described species occur here, and are found
in nearly all parts of the region. Less numerous in species, but
scarcely less distinctive, are the Leiotrichide, or hill-tits, found in
all parts of the Himalaya Mountains; the Pycnodontida, or bul-
buls; Phyllornithids, or green bulbuls; and the minivets of the
genus Pericrocotus, one of the group of caterpillar-eaters. Of the
warblers (Sylviadz), the peculiar tailor-bird (Orthotomus) has about
thirteen to fifteen species. The starlings are represented, among
other forms, by the sacred mynah (Eulabes) and the roseate pastor
(Pastor roseus); the bee-eaters by Merops and the resplendent
Nyctiornis; the sun-birds (Nectarinide) by the Nectarophila and
Arechnothera. The flower-peckers (Diceide), a group of small,
gaily-coloured birds representing the South American sugar-birds,

BIRDS OF THE ORIENTAL REALM. 95

are tolerably abundant throughout the greater portion of the re-
gion. The South American cotingas likewise appear to have
their representatives in the large and gaudy broad-bills (Eurylem-
idx). Trogons, scarcely inferior in the beauty of their plumage
to their American congeners, are sufficiently abundant in the for-
est districts, where, also, we meet with a multitude of the remark-
able horn-bills. Contrary to what might have been expected,
seeing their abundance in the Australian region (and partially so
also in the Ethiopian), and the apparently favourable conditions
for their existence here, the parrots are but feebly represented, and
belong, with one exception—a cockatoo from the Philippine Islands,
the only one found within the limits of the region—to the family
of the ringed-parakeets (Paleornithide). Of the gallinaceous
birds the pheasants (Phasianidz) are largely represented. This is
the home of the jungle-fowl (Gallus), from one of whose species,
the G. Bankiva, inhabiting the region from the Himalayas through
Central India eastward to the islands of Java and Timor, is in all
probability descended the greater portion of our domestic poultry.
Distinct species of the jungle-fowl are found in Southern Hindo-
stan, Ceylon, and Java, and, possibly, some of the domestic varieties
may have been produced as the result of interbreeding between
these various forms and the G. Bankiva. The peacock is found
throughout a considerable portion of the region, to which it is
indigenous, from Ceylon to the Himalayas, and eastward to China;
belonging to the same family, and scarcely less resplendent in their
plumage, are the argus, impeyan, tragopan, and fire-backed pheas-
ants. The remarkable group of Australian birds known as ‘‘mound-
builders,” megapods, or brush-turkeys, constituting the family
Megapodidex, which would seem to be closely related to the South
American curassows, have two representatives (of the genus Mega-
podius), one, possibly introduced, in the Nicobar Islands, and the
other in the Philippines and Borneo.

The reptilian-fauna comprises, among other serpents, the giant
python (of the family Pythonide), the cobra-di-capello (of the
family Elapide, or coral-snakes), and one-half of all the pit-vipers,
or members of the family of rattlesnakes (Crotalide), although
the rattlesnake proper is absent; among lizards, the Varanide, or
water-lizards, to which the monitor belongs, the geckoes, the
agamas, or eastern iguanas, the last embracing no less than eighteen

96 GEOGRAPHICAL DISTRIBUTION.

species of so-called flying-lizards (Draco), animals provided with
a lateral expanded tegumentary membrane ; and of crocodilians,
the true crocodile (Crocodilus) and the gavial (Gavialis), the latter
restricted to the rivers of the Indian Peninsula.

The several faunal sub-regions, especially those of the conti-
nentai tract, are most intimately related to one another, and do not
admit of sharp delimitation. Yet a number of forms, whether
negatively or positively, may be said to define each. Thus, among
the Mammalia, the lion, hyena, fox, lynx, mellivore, buffalo, nyl-
ghau, gazelle, and true antelope, may be said to represent distinct-
ive types of the first, or Indian sub-region, being absolutely restrict-
ed to it, or just passing beyond its confines. The Cingalese sub-
region is characterised, among other forms, by the loris, which it
alone possesses; by a peculiar genus of civet-cats (Onychogale), and
Platacamthomys among the mice. The fauna, especially of the
islarfd of Ceylon itself, is related on the one side to that of the
Himalayas, and on the other to that of the Indo-Malayan sub-region,
differimg broadly from the fauna of the central and northern por-
tions of the Indian Peninsula. The relationship with the Malayan
fauna is especially marked in the case of the Lepidoptera and Cole-
optera among insects, many of the more distinctive or abundantly
represented types belonging exclusively to the two faunas under
consideration. The individuality of the Cingalese reptilian and
amphibian faunas is well marked through the number and variety
of peculiar genera, which, perhaps, more than any other animals,
serve to characterise the sub-region. All the members of the
Uropeltidx, or rough-tailed burrowing-snakes, appear to be ccn-
fined to this tract. The poisonous snakes of the entire peninsula
of India are, according to Fayrer, comprised in eleven genera, rep-
resenting three families, Elapide, Viperide, and Crotalide (pit-
vipers), and some twenty-five species. Among the more venomous
forms are Naja (the cobra, which ascends the Himalayas to a height
of eight thousand feet), Ophiophagus, and Bungarus, of the Ela-
pide; Daboia and Echis representing the vipers; and Trimeresurus
belonging to the pit-vipers. In addition to the terrestrial Thanato-
phidia the marine-snakes (Hydrophide), which inhabit brackish
estuaries and tide-water streams, furnish an additional contingent
of thirty-five or more species.

The two remaining sub-regions, the Indo-Chinese and the Indo-

AUSTRALIAN REALM. 97

Malayan, are most intimately related to each other in the general
characters of their faunas, as they are also to the Indian; the former,
however, incorporates a more decidedly Holarctic element, while
the latter is almost strictly tropical. Among the more distinctive
mammalian types of the Indo-Chinese tract, or such as do not enter
into the composition of the Malayan fauna, are the true bears (Ur-
sus), panda (Ailurus), fox, badger, Arctonyx (Melid), and a pecu-
liar genus of civet-cats, Urva. On the other hand, this tract is
wanting in the anthropoid apes of the genera Simia (orang—Borneo
and Sumatra) and Siamanga (Malacca, Sumatra), the spectre-lemurs
(Tarsius— Sumatra, Borneo), flying-lemur (Galeopithecus), tapir
(Tapirus Malayanus—Malay Peninsula, Sumatra, Borneo), and sun-
bear (Helarctos), which belong to the Malayan fauna. The Hima-
layan districts (with parts of China) are preeminently the home of
the pheasants, which, in addition to several genera peculiar to the
Oriental region (Pavo, Argusianus, Polyplectron, Euplocamus),
comprise a number of forms, the impeyan, tragopan, &c., held in
common with the Holarctic; the peacock ranges from Ceylon and
the Himalayas to Java, and the argus from Siam to Borneo.

THE AUSTRALIAN REALM.

This region, as usually defined, embraces, in addition to the
continent of Australia and the Island of Tasmania, all the Austro-
Malaysian islands lying to the east of Borneo and Bali—. e., begin-
ning with Celebes and Lombok—the vast Polynesian Archipelago,
and New Zealand, with its accompanying islets. This last has by
some naturalists, and more especially by Professor Huxley, been rec-
ognised as a distinct region, although by the majority of zoogeogra-
phers it is usually regarded as a sub-region of the Australian. In
this place only Australia proper (with Tasmania), Papua (New
Guinea, and the minor Papuan islands), and New Zealand are con-
sidered to enter into the formation of the Australian region.

The greater portion of the Australian mainland consists of a
table-land of moderate elevation, characterised by a harsh and dry
climate, and a general absence of water. Hence the surface of the
country bears a more or less barren aspect, supporting but a scant
vegetable growth, which is parched throughout the greater part of
the year, and consequently rendered unfit for promoting a vigorous
development of animal life. A considerable part of the tract passes

98 GEOGRAPHICAL DISTRIBUTION.

off into an almost uninhabitable desert. Along the coast-line, and
more especially on the eastern border, where vapour-condensing sur-
faces present themselves in the form of elevated mountain-crests,
there is an abundance of aqueous precipitation, to which a luxuri-
ous forest-growth responds. Less than one-half of the continent
lies within the tropics. Papua, which constitutes the second sub-
region, exhibits in great part a mountainous character, and, from
the abundance of aqueous precipitation distinctive of the equatorial
portions of the earth’s surface, a vegetation of truly tropical luxuri-
ance. A dense forest growth likewise covers the greater portion
of New Zealand (third sub-region), where also we have the most
elevated mountain-summits in the region.

Zoological Characters of the Australian Realm.—The Aus-
tralian region is, by both positive and negative characters, the most
marked of any on the earth, and, indeed, so remarkable are its faunal
peculiarities that it has been thought by some to constitute properly
in itself a main zoogeographical division, as opposed to the rest of
the world. The most striking feature of this fauna is the general
absence, among the Mammalia, of such forms as, under favourable
conditions, are to be met with in all other portions of the earth’s
surface. In the whole of this region all the terrestrial Mammalia
that are to be found in the Old World are absent, except a solitary
(possibly two) species of hog (Sus), found in New Guinea, the bats,
and rodents, the former being represented by about ten genera,
and the latter by the single family of the mice (Muridz), of which
the true mice (Mus) comprise more than one-third of all the vari-
ous forms. The edentates, insectivores, carnivores, and monkeys,
except such as have been introduced through the agency of man,
and possibly the ‘‘ dingo,” or Australian wild-dog, which may prove
to be indigenous, are wholly wanting, their place being filled by a
wonderful variety of the implacental mammals—the marsupials and
monotremes—the lowest of the entire mammalian series. No im-
placental mammals occur at the present time in any portion of the
Old World outside of the limits of the Australian and the connect-
ing Austro-Malaysian regions, and their only representatives in the
Western Hemisphere are the opossums (Didelphyid), upwards of
twenty species of which range throughout the forest districts of the
Neotropical realm (with two species in North America). The Aus-
tralian marsupials fall into six distinct families: The Macropodide,

AUSTRALIAN MAMMALIA. 99

kangaroos and kangaroo-rats, are numerically the most important
and the ‘most broadly distributed of the several types, and com-
prise a diversity of forms, which are variously adapted to living
- in the scrub, in the desert, along rocky and precipitous mountain
summits (Petrogale), or on trees. The arboreal genus Dendrolagus is
thus far known only from New Guinea and Queensland. The great
kangaroo (Macropus giganteus), inhabiting the southern half of
the continent of Australia and Tasmania, attains in the male a
length, from the tip of the nose to the root of the tail, of upwards
of five feet. The kangaroo-rats, rat-kangaroos, or potoroos (Hypsi-
prymnus), are diminutive forms, of about the size of a hare, with
rounded instead of elongated ears, and a general rat-like appearance.
The second family is that of the Dasyuride, or native cats, a group
of carnivorous and insectiyorous marsupials, which range in size
from the dimensions of a mouse to those of a wolf. The most dis-
tinctive forms belong to the genus Antechinus, a group of insect-
ivorous animals, which, in outward appearance, are but barely dis-
tinguishable from the ordinary mice. The most formidable member
of the family is the Tasmanian “tiger,” or ‘“ hyena” (Thylacinus
cynocephalus), a striped carnivorous marsupial, having the general
aspect of a wolf or dog, which it also fully equals in size, measuring
as much as five feet in length. The third family is that of the
Myrmecobiide, which includes but a single species, the native ant-
eater, or striped myrmecobius (M. fasciatus), a small squirrel-like
animal, of about the size of the common squirrel, inhabiting South-
ern and Western Australia. The Paramelidez comprise the bandi-
coots (Perameles), small kangaroo-like animals of about the size of
the rabbit, and the singular pig-footed marsupial known as the
Cheropus, a graceful animal somewhat recalling in appearance
the mouse-deer of the Oriental region. The fifth family, the Pha-
langistids, exhibits in its individual components a greater diversity
of form, and greater specialisation of structure, than is to be found
in any other mammalian family. As described by Wallace, we find
represented in this family the tailless koala, or native sloth (Phas-
colarctos); the prehensile-tailed opossum-like phalangers (F halan-
gista); the beautiful flying-opossums (Petaurista, Belideus, Acro-
bata), so closely resembling in form the flying-squirrels of North
America and India, but often no larger than a mouse; the dormouse-
like Dromicia, one species of which does not equal in size the ordi-

100 GEOGRAPHICAL DISTRIBUTION.

nary harvest-mouse; and, finally, the little Tarsipes, a true honey-
sucker, provided with an extensile tongue, and of the size of a
mouse. All of these various forms are more or less adapted to an
arboreal existence. The remaining family of the marsupials is that
of the wombats (Phascolomyide), nocturnal burrowing animals of
about the size of the badger, and somewhat of the appearance of a
bear, subsisting chiefly on roots and grasses. The most anomalous
and remarkable of all the Australian mammals, indeed of all Mam-
malia, are the oviparous monotremes—the duck-bill (Ornitho-
rhynchus) and native hedge-hog (Echidna)—strictly speaking, bur-
rowing edentate animals, having certain points of affinity with both
birds and reptiles. With few exceptions (Cuscus, Belideus), all
the marsupial genera of the Australian region are confined to the
continent of Australia, Tasmania, and New Guinea (and the Aru
Islands), but a very insignificant fraction of the entire number of
marsupial species being represented in any of the Austro-Malaysian
islands (Mysol, Celebes). Even in New Guinea, a3 compared with
Australia, the number of such representatives is rather limited;
but we here meet with at least one type of placental mammal, the
hog, which is not met with on the continent of Australia. On the
other hand, the (in Australia) fairly well represented family of rats
and mice exhibits in the Papuan sub-region (Aru Islands) but a
solitary example, the Uromys.

In respect of its bird-fauna, the Australian region presents us
with peculiarities that are scarcely less marked than those which
distinguish the Mammalia. In the number and beauty of its forms
this region is only second to the Neotropical, while in such as
show the most marked peculiarities of structure it is unsurpassed.
Many of the most familiar types of Old World birds are repre-
sented, and in sufficient number—such as the warblers, thrushes,
fly-catchers, shrikes, and crows; but, on the other hand, some of
the most broadly diffused families are wholly wanting. Thus, the
true finches (Fringillide), which have otherwise a universal dis-
tribution, appear to be wanting in all parts of the region, being
replaced by the weaver-finches (Ploceidz). The vultures are also
completely absent, as are likewise the woodpeckers (Picide) and
pheasants (Phasianidx). The true paradise-birds (Paradiseine),
whose special development in New Guinea and the other Papuan
Islands forms such a marked feature in the avian-fauna of that sub-

BIRDS OF THE AUSTRALIAN REALM. 101

region, have but two representatives (Manucodia) on the Australian
mainland; the bower-birds (Tectonarching), on the other hand—
members of the same family—have here their greatest development
(seven species), and are associated with two species of rifle-birds
(Ptiloris). The Australian region is distinguished by being the
sole possessor of the families of lyre-birds (Menuride) and apteryxes
(Apterygide), the latter one of the most remarkable groups of ex-
isting birds (natives of New Zealand), whose exact relationships
have not yet been satisfactorily determined. The struthious birds
of the genus Dromeus, the emu (two species), are confined to the
continent of Australia, as is also one of the genera of brush-turkeys
(Leipoa). Talegallus, the true brush-turkey, and Megapodius, the
megapod or mound-builder, have both representatives in the Papuan
Islands and Australia, the former being restricted to the region
under consideration. The greater number of the species of Mega-
podidew, some twenty or more, are distributed throughout the
Austro-Malaysian islands and Polynesia, with two outlying species
in the Philippines, Borneo, and the Nicobar Islands. The parrots
have an extensive development, and represent in the main forms
that are not known beyond the limits of this and the transition
region. ‘‘No group of birds gives to Australia so tropical and
foreign an air as the numerous species of this great family, by
which it is tenanted, each and all of which are individually very
abundant. Immense flocks of white cockatoos are sometimes seen
perched among the green foliage of the loftiest trees; the brilliant
scarlet breasts of the rose-hills blaze forth from the yellow flowering
Acaciz; the Trichoglossi or honey-eating parakeets enliven the
flowering branches of the larger Eucalypti with their beauty and
their lively actions; the little grass parakeets rise from the plains
of the interior and render these solitary spots a world of anima-
tion; nay, the very towns, particularly Hobart Town and Adelaide,
are constantly visited by flights of this beautiful tribe of birds,
which traverse the streets with arrow-like swiftness, and chase each
other precisely after the manner the Cypseli are seen to do in our
own islands. In Tasmania I have seen flocks of from fifty to a
hundred of the Platycercus flaviventris, like tame pigeons, at the
barn-doors in the farm-yards of the settlers, to which they descend
for the refuse grain thrown out with the straw by the threshers.?* ”
About sixty species of the order are known from the mainland of

102 GEOGRAPHICAL DISTRIBUTION.

Australia alone. The Cacatuide, which are found only in this
and the adjoining transition region, with a solitary species, Caca-
tua hematuropygia, in the Philippines, comprise, among other forms,
the commoner species of the genus Cacatua, as the sulphur-crested
and rose-breasted cockatoos, and the black cockatoos of the genus
Calyptorhynchus, which last are restricted to the continent of Aus-
tralia and Tasmania. An aberrant group of the parrots are the
New Zealand nestors (Nestoride), some of whose members appear
to be addicted to carnivorous habits,*® and which would seem to
have certain points of relationship with the South American ma-
caws. In New Zealand, likewise, are found the owl-like nocturnal
parrots of the family Strigopide. One of the most distinctive
groups of birds of the Australian region are the honey-suckers
(Meliphagide), whose representatives are scattered all over the
Austro-Malaysian and Polynesian groups of islands, from Celebes
to the Marquesas Islands, and from Tasmania to Hawaii. Of some
two hundred or more species of this family but a single one,
Ptilotis limbata, enters the Oriental region (the Island of Bali).
The nearly related honey-suckers (Nectarinide) are represented by
several forms more or less distinctive of the region (Arachnecthra,
Arachnothera). Australia with New Guinea, and the adjacent isl-
ands, may be considered to be par excellence the natural home of
the pigeons (Columbee), nearly one-half of the total number of
genera (forty or more) being represented here, and by types many
of which are found nowhere else. They include the most gaudily
ornamental representatives of the order (Ptilopus), which in the
brilliancy of their plumage yield but little to the parrots ; various
forms of ground-pigeons (Geophaps, &c.); and the beautiful crested-
pigeon known as the goura, from New Guinea and some of the
adjacent islands. The turtle-dove (Turtur) is found in New Guinea,
but the nearly universally distributed Columba, to which the or-
dinary rock- or wild-pigeon (C. livia) belongs, and which represents
the ancestral form of most of our domestic breeds, is wanting.

The reptile-fauna of this region is much less distinctive than
either the mammalian or avian. Snakes, amphibians (but only the
tailless forms), and lizards are abundant, the great bulk of the last
being constituted by the scinks and geckoes. Of the amphibians
the true toads (Bufonide) are represented by a limited number of
species in Australia, although the genus Bufo itself is wanting;

TFOLYNESIAN REALM. 103

Rana, the frog, has a single species on the peninsula of York (R.
Papua), but is more abundant in New Guinea. Tree-frogs (Hyla)
are numerous. A peculiarity distinguishing the continental ophidian
fauna is the great preponderance of venomous over non-venomous
serpents. The proportion of the former to the latter is in some
sections, as in South Australia, as six to one. Two-thirds of all
the species belong to the family Elapide, to which the American
coral-snakes and the Indian cobra also belong. One species of
crocodile is found in some of the Australian waters.

The fish-fauna is very limited, less than forty species being
known from the entire realm. Two species of lung-fishes, the
‘‘barramundas” (Ceratodus Forsteri and C. miolepis), inhabit the
waters of Queensland. The paucity of forms is, doubtless, in part
attributable to the limited number of fresh-water streams.

THE POLYNZSIAN REALM.

The scattered island groups of the Pacific Ocean are so deficient
in the faunal elements that distinguish the main zoogeographical
divisions of the earth that they may be said to constitute a region
framed more by negative than by positive characters. For this
reason they have by many naturalists been relegated to the rank of
a mere sub-region. Yet, when we compare the Polynesian fauna
with the faunas of the other recognised regions, it becomes not a
little difficult to determine just where it should be placed, although
there would seem to be hardly a question as to the preponderating
relationship being with the Australian fauna, with which it has
generally been united. The addition, however, of so enormous
an annex to a region which combines in its faunal elements such a
remarkable individuality, and with which, after all, there is not very
much in common, does not appear natural; and the less so, when
we recognise the full importance of the characters derived by the
Polynesian tract from regions other than the Australian, and its
own special peculiarities. For these reasons it seems advisable to
consider the region as one apart by itself.

Zoological Characters of the Polynesian Realm.—This tract
is at once distinguished from the Australian, as well as from all
others, by the abscence of all Mammalia excepting bats. Of these
last there are representatives of two families, the Oriental fruit-

104 GEOGRAPHICAL DISTRIBUTION.

eating bats, or flying-foxes (Pteropide), and the cosmopolitan Ves-
pertilionide, distributed almost everywhere throughout the region.
The flying-foxes are, however, absent from both New Zealand and
the Sandwich Islands. The more important families of birds are
mainly such as have an extensive representation in the Australian
realm, or are held in common by this and the Oriental or Ethio-
pian realm. Among these are the caterpillar-eaters (Campephagi-
dx), flower-peckers (Diceidz), weavers (Ploceidz), and swallow-
shrikes (Artamide). With insignificant exceptions all the families
of birds that are wanting in the Australian region are likewise
wanting here; in addition to which, several of the more representa-
tive families of Australian birds, as the birds-of-paradise, bower-
birds, lyre-birds, cassowaries, cockatoos, and apteryxes, are also
wanting. On the other hand, the region contains three families
which are absolutely confined to it ; these are the dodo-pigeons
(Didunculide), from the Samoan Islands, the Drepanide, from the
Sandwich Islands, and the heron-like Rhinochetide, from New
Caledonia. The mound-builders (Megapodide) and honey-suck-
ers (Meliphagide) have a very extensive distribution. The more
nearly cosmopolitan families include among others the thrushes,
warblers, crows, cuckoos, king-fishers, swallows, goat-suckers, swifts,
pigeons, falcons, owls, and herons. Most of the genera of Sand-
wich Island birds are peculiar; hence it might be considered
doubtful whether the tract inhabited by them should properly be
considered to constitute a part of the region under considera-
tion.

The reptile-fauna is feebly developed. Lizards, principally
geckoes and scinks, range throughout the greater part of the
region, as do likewise a very limited number of serpents, which
are, however, absent from the more distant islands. The appear-
ance of a member of the American family of Iguanids (Brachylo-
phus) in the Feejee Islands is not a little surprising. Three species
of Cornufer (Ranidz) inhabit the Feejee Islands, and Bufo dialo-
phus apparently the Sandwich Islands, but otherwise the Amphibia
are almost wholly wanting. The fresh-water fishes are very limited
in number, and exhibit a remarkable sameness throughout, com-
prising principally such forms—eels, atherines, mullets, gobies—
as can readily accommodate themselves to brackish-water condi-
tions. A siluroid (Arius) is found in the Sandwich Islands.

TYRRHENIAN TRANSITION REGION. 105

THE TYRRHENIAN TRANSITION REGION.

The fauna of this region is an association of elements derived
from the faunas of the Holarctic, Ethiopian, and Oriental realms,
with a preponderance on the north side of the Mediterranean of
the Holarctic element, and on the south side probably of the Ethio-
pian. The number of absolutely peculiar forms, or of forms which
barely pass beyond the confines of this tract, is not great. Among
the Mammalia we have three such genera: Dama, the fallow-deer,
found on both sides of the Mediterranean; Addax, an antelope,
confined to North Africa and Syria; and Psammomys, a mouse,
restricted to Egypt and Palestine. By far the greater number
of the mammalian types occurring on the north side of the Medi-
terranean are such as might be considered to belong to the Euro-
pean division of the Holarctic tract ; but yet there are a con-
siderable number of both genera and species which are entirely
or nearly unknown there, and which either represent peculiarities,
or forms belonging to the more tropical regions to the south.
Such are the genet, ichneumon (found in Spain), porcupine, jackal
(Dalmatia), Corsican deer (Cervus Corsicanus), and moufflon (Cor-
sica, Sardinia, Crete, mountains of Greece). Until quite recently,
too, the indigenous animals included also the lion and hyena.
The ape of the Rock of Gibraltar (Macacus Inuus), although found
on the Barbary coast, is more strictly an Oriental type. The Ethio-
pian affinities are further established on the African and Asiatic
sides by the elephant-shrews (Macroscelididz), coney (Syria), the
antelopes of the genera Oryx, Alcephalus, and Gazella, and several
additional members of the larger Carnivora—leopard, serval, and
hunting-leopard. In the early part of this century the hippopota-
mus still inhabited Lower Egypt. The wild-asses which inhabit
the desert plains included between the Red Sea and the Indus
River may be considered as a link between the Holarctic and
Ethiopian faunas.

The bird-fauna is on the whole very much more nearly Hol-
arctic than anything else, a very large proportion of the species
being such as inhabit Europe north of the Alps. But this is
due in considerable part to the interchanges which are effected
through the northerly and southerly migrations. According to
Canon Tristram,* no less than two hundred and sixty out of three

106 GEOGRAPHICAL DISTRIBUTION.

hundred and twenty-two species of birds inhabiting Palestine are
European forms, one hundred and thirty-four species (land and
water birds) being common to Britain and Palestine. Of the Per-
sian avi-fauna one hundred and twenty-seven species are also found
in Europe.“ Of the Oriental and Ethiopian birds which are not
known north of, or barely transgress, the Tyrrhenian tract, may be
mentioned the francolin, the quail-like Turnix, pastor, honey-
sucker (Nectarinea), hoopoe (Upupa), oriole, Ceryle and Halcyon
among the kingfishers, the bee-eater (Merops), flamingo, and the
genera Gyps, Vultur, and Neophron among the vultures. The
ostrich enters the desert regions of Syria.

The reptilian and amphibian faunas contain a very considerable
number of forms peculiar to the region. Of some fifty-three species
found in Italy, only twenty-six penetrate into the region north of the
Alps, and of this number from five to eight also enter the Ethiopian
region.** According to Béttger, of the forty species inhabiting
Morocco, twenty-two also belong to Spain, and but seven of these
pass into the northerly Holarctic tract. On the other hand, only
eight of the Moroccan species are known to inhabit the Ethiopian
region, Algeria, according to the researches of Strauch, is repre-
sented by seventy-six species, of which twenty-seven are also Italian,
and but ten Holarctic. On the other hand, eleven species are
positively known to inhabit the Ethiopian region, and, according
to Forsyth Major, not unlikely eighteen others will also be found to
do so.**

THE SONORAN TRANSITION REGION.

This tract, which, as already stated, comprises the peninsula of
Lower California, the State of Sonora in Mexico, New Mexico, Ari-
zona, and parts, not yet absolutely defined, of Nevada, California,
Texas, and Florida, is, as far as the Mammalia and birds are con-
cerned, not very clearly differentiated ; the intermingling of northern
and southern elements, with a decided preponderance in favor of
the former, is very great, and the peculiarities insignificant. Two
species of Bassaris, a member of the raccoon family, appear to be
confined to California, Texas, and the highlands of Mexico. Among
the more peculiarly Neotropical forms that enter the tract are the
jaguar, the peccary, a solitary species of armadillo, and a bat of the
genus Nyctinomus. The reptilian and amphibian faunas are much

AUSTRO—MALAYSIAN TRANSITION REGION. 107

more distinctly of a southern than of a northern facies. Of some
filty-five or more species of lacertilians, very nearly three-fourths of
the number are iguanas (Iguanid), and four are geckoes. Fully
one-half of the total number of genera represented are not found in
other portions of the North American continent. The serpent-
fauna comprises about twenty-two genera, one-half of which are
peculiar. Eleven of the thirteen species of North American rattle-
snake are found here ; the otherwise common coluber is wanting.
Among the tailless amphibians, the Bufonidz (Bufo) have their
headquarters here, more than one-half of all the North American
species being represented. The tree-frogs (Hylidx), and frogs
proper (Ranide), are, on the other hand, both very deficient. The
tailed amphibians, of which there are upwards of fifty species in
the region to the north, are almost completely wanting. **

THE AUSTRO-MALAYSIAN TRANSITION REGION.

This region, which is situated intermediately between the Ori-
ental and Australian realms, naturally partakes of an intermediate
position also in respect of its fauna. While the animal types bor-
rowed from the adjoining regions preponderate to a very marked
extent, the number of specific forms that are absolutely peculiar,
especially among birds, is very remarkable. According to Mr.
Wallace nearly three-fourths of some two hundred species of land-
birds inhabiting the Moluccas are peculiar to those islands, and very
nearly one-half of a hundred and fifty or more species found on the
island of Celebes are absolutely confined to it. Yet, of the one
hundred and twenty genera here represented (Celebes), only nine
are peculiar. With few exceptions, all the families of birds that
are represented in either the Australian or the Oriental region are
also represented here. As belonging to the former, the birds-of-
paradise have but a single species, the standard-wing (Semioptera
Wallacei), found in the islands of Gilolo and Batchian; the honey-
suckers appear to be almost entirely absent from Celebes, although
they are to be found in several of the other islands. The Oriental
babbling-thrushes (Timalidz) and bulbuls (Pycnonotid) barely en-
ter, while the hill-tits (Leiotrichidee) are completely wanting. It is
not a little remarkable that the creepers (Certhiade), stone-hatches
(Sittide), and tits (Paridx), which have their representatives in

108 GEOGRAPHICAL DISTRIBUTION.

the regions on either side of this one, should be entirely wanting
here.

The placental Mammalia are represented by about twenty
species, exclusive of the Cheiroptera, mainly of Asiatic types. Six-
teen of these are found on the island of Celebes, and comprise sev-
eral rodents (mice and squirrels), a wild-hog, a deer (Cervus hip-
pelaphus), very closely related to, if not identical with, a Javan
species; a civet-cat, a spectre-lemur (Tarsius spectrum), and three
peculiar forms, unlike anything found either on the continent of
Asia or the Malayan islands. These are a black and almost tailless
baboon-like ape (Cynopithecus nigrescens), an antelopean buffalo
(Anoa depressicornis), and the babyroussa (Babirusa alfurus).
Several of these, or closely allied forms, are also found in the
Moluccas, and in the group of islands and islets which stretch
eastward from Lombok to Timor. We have here, in addition, one
of the commonest species of Malay monkey, the Macacus cynomol-
gus, a Paradoxurus, and a possible second species of deer, Cervus
Timoriensis. The implacental mammals of the connecting region
comprise only Cuscus and Belideus.

Distribution of marine life.—Nature of the deep-sea fauna.—Oceanic pelagic
fauna.—Littoral fauna.—Pelagic faunas of lakes.—Deep-lake faunas.

DISTRIBUTION OF MARINE LIFE.

OnE of the most important results of deep-sea explorations is
the establishment of the fact that the distribution of oceanic life
has no depth-limit. Contrary to the opinion so long entertained
by naturalists that this life was confined to a shallow zone, extend-
ing but a few hundred feet beneath the water’s surface, it is now
known that representatives of all the marine invertebrate classes,
and probably also fishes, exist at the greatest depths that have been
reached by the dredge, and that in all likelihood a fair proportion of
these penetrate even to the profounder abysses of four or five miles.
The most extensive organic deposits accumulating in the trough of
the sea are made by the Radiolaria and Foraminifera, whose world-
wide distribution and prodigious development give the determining
character to the oceanic floor. The well-known ‘ Globigerina,” or
‘* Atlantic”? ooze, a composition in principal part of the calcareous
tests of four or five genera of Foraminifera (Globigerina, Orbulina,
Spheroidina), constitutes the bed of the sea at nearly all points be-
tween the depths of four hundred and two thousand, or two thou-
sand five hundred fathoms, except where, as in the immediate
neighbourhood of coast-lines, the bottom is formed by the conti-
nental debris. Over this vast calcareous area animal life is far more
abundant than over the comparatively sterile region where, for any
reason, the ooze is wanting, and where, consequently, there is a
marked deficiency in the material necessary for the proper develop-
ment of many of the lower forms of life. Thus, it has been noticed
that in such localities chiefly the shell-less orders of animals, as the
Holothuroidea and the Annelida, are represented. Beyond a depth

110 GEOGRAPHICAL DISTRIBUTION.

of some two thousand five hundred fathoms shell accumulations
almost completely cease, their place being taken by a *‘ red-clay”
deposit, whose exact nature is, perhaps, not yet clearly understood.
The absence of foraminiferal tests from the areas of greatest depth
is doubtless due to the dissolution of the calcareous matter of the
shell during its descent from the surface to the bottom, most of the
pelagic forms, there is good reason to believe, being restricted in
their range to a superficial zone of a few hundred fathoms depth.

The sponges, although they attain a maximum development in
a zone of five hundred to one thousand fathoms, extend to the
greatest measured depths, and are represented in the deepest parts
by all the recognised orders, with the exception of the Calcarea
(calcareous sponges), which appear to be confined to shallow water.
The Hexactinellidz, among siliceous sponges, to which the ‘ glass-
rope sponge” (Hyalonema) and Venus’ flower-basket (Euplectella)
belong, and whose earliest representatives appear already in the
fauna of the Cambrian period, preponderate in the abyssal regions.
The ordinary horny sponges (Keratosa), while they possess a very
considerable vertical range, have their special development in the
coralline zone. In the deepest parts of the sea corals are but spar-
ingly distributed, and by far the greater number of species belong
to the type of simple corals, and to the family Turbinolid, a large
proportion of the genera passing back to the Tertiary period, and a
few to the Cretaceous. No true Paleozoic forms have as yet been
discovered. But five genera of Madreporaria are known whose
range extends to, or exceeds, fifteen hundred fathoms (nine thou-
sand feet), and only a single one, Bathyactis, which transgresses the
twenty-five hundred fathom line. The vertical range of some of
the species is very extraordinary, most notably so in. the case of
Bathyactis symmetrica, which is found in all depths between thirty
(Bermuda) and twenty-nine hundred fathoms (east of Japan).*°

Several species of Medusz have been obtained from depths re-
ported to exceed two thousand fathoms; but it is, perhaps, open
to question whether some, or even most, of these apparently deep-
sea forms are not in reality inhabitants of a comparatively shallow
superficial zone, and have not been simply caught in the hauling of
the net. There appears to be strong evidence, however, for con-
cluding that at least a few of the forms are actually inhabitants of
deep water.

DEEP-SEA FAUNA. 111

Among the deep-sea Echinodermata there are representatives of
all the modern orders—crinoids, brittle-stars, star-fishes, urchins,
and holothurians—but none of the ancient palechinoids, cystids, or
blastoids are known. The pear-encrinites (Apiocrinide), for a long
time supposed to have become extinct with the Mesozoic era, con-
tinue their succession in the genera Rhizocrinus, Bathycrinus, and
Hyocrinus, forms more strictly abyssal in character than the Penta-
crinus, whose greatest development seems to be confined to a zone
of a few hundred fathoms. Bathycrinus gracilis has been dredged
in water of a depth of two thousand four hundred and thirty - five
fathoms. **

The Asteroidea (cae Bares and Ophiuroide (brittle-stars) are
diffused throughout all the oceanic zones that have thus far been
dredged, the former abounding more particularly at moderate
depths. The singularly aberrant, and universally distributed, genus
of star-fishes, Brisinga, is one of the commonest and most distinct-
ive forms of the abyssal fauna, being found in all depths from four
hundred to three thousand fathoms. Of the brittle-stars, of which
there are about five hundred species described, more than two hun-
dred are restricted in their range to a zone of thirty fathoms. De-
spite this apparent localisation of the species to a shallow belt, there
are no less than sixty-nine species which descend below one thou-
sand fathoms, and about eighteen below two thousand. None of
the genera have been positively identified with fossil forms, although
not unlikely the Jurassic Ophioderma may in part belong to Ophiura
or Pectinura. The affinities of the Triassic Aspidura are still doubt-
ful.*’ The relationship existing between the modern echinoid fauna
and the faunas of past geological periods is much more marked;
indeed, this relationship may be considered as one of the most dis-
tinctive features of the deep-sea fauna. Not only do a considerable
number of the living genera date back to the Cretaceous period,
but a fair proportion of those of the families Cidaride, Echinide,
Salenidz, &c., are already found in the deposits of the Jura, the
Lias, and even in the Trias. The Tertiary genera are very largely
developed, and the utmost similarity prevails, even among the spe-
cies. So close is the identity existing between the West Indian
urchins and those occurring fossil in many of the European Tertiary
beds (older and median Tertiary), that it becomes practically im-
possible, or nearly so, to distinguish between the species.** This

112 GEOGRAPHICAL DISTRIBUTION.

correspondence manifests itself among both the regular and irregu-
lar forms. In their bathymetrical distribution the echinoids appear
to be governed by much the same conditions as have been observed
in the case of the brittle-stars. By far the greater number of spe-
cies—about two hundred—are of a littoral habit, occupying the
belt of one hundred to one hundred and fifty fathoms, although not
a few of them, like Echinocardium Australe, which descends to
two thousand six hundred and seventy-five fathoms, penetrate deep
into the abyssal zone. The number of continental species, or such
whose normal habitat is included approximately between the one
hundred to one hundred and fifty and the five hundred fathom line
is forty-six, and a slightly larger number, fifty, may be considered
to be strictly abyssal. The species passing below two thousand
fathoms are rather limited, and only one is known—Pourtalesia
laguncula—whose range embraces the twenty-nine hundred fathom
line. This form is also found in the continental belt.*°

The sea-cucumbers, or holothurians, which are very generally
distributed throughout the oceanic abyss, constitute one of the
most distinctive elements of the deep-sea fauna. As has already
been seen, they, together with certain annelids, form a large part
of the fauna of the ‘‘red clay,” or of the region which lies beyond
the reach of foraminiferal shells.

Deep-sea crustaceans are very abundant, and many of them are
remarkable for their colossal size, their bizarre forms (Nematocar-
cinus gracilipes), and brilliant red coloring. Partaking of the first
character are the giant blood-red shrimps of the genus Aristzeus,
and several members of the order Schizopoda. A Gnathophausia
was obtained off the Azores, by the officers of the ‘‘ Talisman,”
measuring no less than twenty-five centimetres (nearly ten inches)
in length. The peneid and caridid shrimps, among the long-tailed
decapods, are strikingly numerous, and present many very singular
forms. It would seem, from the observations of the ‘“‘ Challenger,”
that the Brachyura, or crabs, were confined almost entirely to com-
paratively shallow water, although at depths of one thousand to
fifteen hundred fathoms they appear to have yielded a sufficient
harvest to the naturalists of the French expedition. Hermit-crabs
were collected by the ‘‘ Talisman ” in water of from four thousand to
five thousand metres.*® Many of the pedunculated barnacles are of
uncommonly large size, surpassing in this respect the shallow-water

DEEP-SEA FAUNA. 113

forms. As might have been expected from our knowledge of cave-
faunas, and the habits of those animals, there are a number of blind
crustaceans inhabiting the deep, as Nephropses, Polycheles, &c.,
the last in a manner representing the Jurassic Eryon. Many of the
species, on the other hand, are profusely phosphorescent.

Neither of the three more important orders of mollusks, the
Lameilibranchiata, Gasteropoda, or Cephalopoda, enter very largely
as components of the deep-sea fauna, although of the first two scat-
tered individuals are not exactly uncommon at nearly the greatest
depths. Leda and Arca were obtained from a depth of 16,000
feet. The Cephalopoda are the least numerous, and not unlikely
the majority of the apparently deep-water forms represent in reality
only captures from shallow water. Wyville Thomson has called
attention to the remarkable fact that only on one occasion did the
officers of the “ Challenger” take the animal of Spirula, ‘although
the delicate little white coiled shell is one of the commonest objects
on the beach throughout the tropics—sometimes washed up in a
long white line, which can be seen from any distance.” *' The
Brachiopoda, while enjoying a very broad geographical distribu-
tion, are by no means numerous, either specifically or numerically.
Although seemingly on the verge of extinction, it would appear as
though the actual specific diminution since the beginning or middle
of the Tertiary period has not been very great. Most of the recent
species are technically shallow-water forms, by far the greater num-
ber being found above the five hundred fathom line. Ten species
range to depths of six thousand feet and over, and one, Terebratula
Wyvillei, was dredged in twenty-nine hundred fathoms. All depths
have furnished specimens of Polyzoa.

Our knowledge respecting the bathymetrical distribution of the
deep-sea fishes, owing to the difficulty of determining whether the
specimens hauled by the net have been actually taken in the depths
indicated by the sounding-line, or have been simply captured dur-
ing the ascent of the net, is not very precise, and barely sufficient
to permit of any general conclusions being drawn from it. That
fishes abound at very great depths there can be no question; but
whether they are equally distributed in the great zone lying be-
tween the surface and bottom waters, may still be considered
doubtful. The researches of the ‘‘ Challenger” would seem to in-
dicate that this intermediate area is largely, if not almost wholly,

114 GEOGRAPHICAL DISTRIBUTION.

destitute of such forms, whereas the evidence brought by the
‘‘Talisman” tends in just the opposite direction. Thus, in one
haul taken off the Cape Verde Islands, in four hundred and fifty
metres water, the net brought up no less than one thousand and
thirty-one fishes, mostly belonging to the genus Melanocephalus.*”
At depths of one thousand to one thousand five hundred metres in
the North African Atlantic, they are stated by Milne-Edwards to
abound, and on the bank lying some one hundred and twenty miles
off Cape Nun, where in water of from two thousand to two thousand
and three hundred metres M. Vaillant obtained the singular Eury-
pharinx pelecanoides, they are still very varied. Many of the species
possess an extraordinary vertical range, accommodating themselves
apparently with ease to the most varied conditions of pressure.
Alepocephalus rostratus is met with in a zone included between
nine hundred and three thousand six hundred and fifty metres, and
much the same distribution characterises Scopelus Madcrensis.
Macrurus affinis is found between five hundred and ninety and two
thousand two hundred metres. The greatest depth from which
any fish has been obtained is about five thousand metres (Bathyopis
ferox):**

The deep-sea fishes, although frequently characterised by many
very remarkable abnormalities of structure, such as the enormous
development of the head or jaw, the ribbon-like body, and the
possession of phosphorescent organs, do not belong to any peculiar
order, and are in the main simply modified forms of surface types.
A large proportion of the species belong to the families Ophidiida,
Scopelide, and Macruride.

In summing up the results obtained from a first general survey
of the collections obtained by the ‘ Challenger,” Sir Wyville
Thomson believes that we are warranted in arriving at the follow-
ing general conclusions : **

‘1, Animal life is present on the bottom of the ocean at all
depths.

‘©2. Animal life is not nearly so abundant at extreme, as it is
at moderate depths; but, as well-developed members of all the
marine invertebrate classes occur at all depths, this appears to de-
pend more upon certain causes affecting the composition of the
bottom deposits, and of the bottom water involving the supply of

DEEP-SEA FAUNA. 115

oxygen, and of carbonate of lime, phosphate of lime, and other
materials necessary for their development, than upon any of the
conditions immediately connected with depth.

‘<3, There is every reason to believe that the fauna of deep
water is confined principally to two belts, one at and near the sur-
face, and the other on and near the bottom; leaving an intermediate
zone in which the larger animal forms, vertebrate and invertebrate,
are nearly or entirely absent.

‘‘4. Although all the principal invertebrate groups are repre-
sented in the abyssal fauna, the relative proportion in which they
occur is peculiar. Thus Mollusca in all their classes, brachyurous
Crustacea, and Annelida, are on the whole scarce; while Echino-
dermata and Porifera greatly preponderate.

‘5. Depths beyond five hundred fathoms are inhabited through-
out the world by a fauna which presents generally the same features
throughout; deep-sea genera have usually a cosmopolitan extension,
while species are either universally distributed, or, if they differ
in remote localities, they are markedly representative; that is to
say, they bear to one another a close genetic relation.

‘¢6, The abyssal fauna is certainly more nearly related than the
fauna of shallower water to the faunz of the Tertiary and Sec-
ondary periods, although this relation is not so close as we were
at first inclined to expect, and only a comparatively small num-
ber of types supposed to have become extinct have yet been dis-
covered.

‘‘7, The most characteristic abyssal forms, and those which are
most nearly related to extinct types, seem to occur in greatest
abundance and of largest size in the Southern Ocean; and the gen-
eral character of the fauns of the Atlantic and of the Pacific gives
the impression that the migration of species has taken place in a
northerly direction, that is to say, in a direction corresponding with
the movement of the cold undercurrent.

‘*8. The general character of the abyssal fauna resembles most
that of the shallower water of high northern and southern latitudes,
no doubt because the conditions of temperature, on which the dis-
tribution of animals mainly depends, are nearly similar.” (‘‘ The
Atlantic,” II.)

Nature of the Deep-Sea Fauna.—Much diversity of opinion
exists among naturalists as to the nature of the deep-sea fauna.

116 ; GEOGRAPHICAL DISTRIBUTION.

That it is not one governed by conditions of temperature alone,
or in principal part, as has very generally been conceived, is made
manifest by an examination of the bathymetric distribution which
particular animal groups affect. Thus, the reef-building corals,
which for their proper development require an average tempera-
ture of 70° to 75° Fahr., and a temperature never falling below 68°
Fahr., are confined to a superficial zone of twenty fathoms; yet
at most parts of the oceanic surface inhabited by these animals a
suitable temperature would be found at depths fully five times as
great, and in some quarters even very much greater. Over the
tropical Pacific, for example, a temperature of 77° Fahr. prevails to
a depth of eighty fathoms, and of 70° Fahr. down to one hundred
fathoms, so that, as far as temperature alone is concerned, the
coral animal might just as well have found a congenial home in
those greater depths as in the shallower one of ten to twenty fath-
oms. Indeed, in the Red Sea the coral isotherm would still be
found at the very bottom, or in a depth of water of six hundred
fathoms; but here, as elsewhere, the limiting line is found at twenty
fathoms. With reference to the vertical distribution of these ani-
mals, therefore, the matter of temperature would seem to be but
little involved.

What is true of the corals doubtless applies in considerable
part to many other animal groups; but it must be confessed that
our knowledge respecting the thermal conditions necessary for the
existence of most marine organisms is so limited that we can hardly
premise at the present day upon any safe deduction being based
upon it. Professor Fuchs *° has quite recently emphasised the fact,
however, as tending to prove the non-influence of temperature in
determining distribution, that over the entire world almost all
the important types of the deep-sea fauna are already represented
at the comparatively insignificant depth of ninety to one hundred
fathoms, and consequently inhabit a zone the extremes of whose av-
erage temperature may be separated by fully thirty to forty degrees.
Thus, it is pointed out that on the Pourtales Plateau, off the coast
of Florida, which begins at ninety fathoms, and descends to three
hundred fathoms without showing any essential modification in its
inhabiting fauna, deep-sea forms are very plentiful, especially corals,
siliceous sponges, and echinoderms; and the same is the case with
the famous Barbadoes grounds. A well-marked deep-sea fauna has

DEEP-SEA FAUNA. 117

long been recognised in the Atlantic and Mediterranean waters of
Europe as occupying the one hundred fathom zone; and it has been
equally observed along the coast of Brazil, the Philippines, and
elsewhere. The fact that almost everywhere this upper limit of
faunal distribution should correspond with a line of nearly uniform
depth is certainly very remarkable, and one that argues strongly
against the notion of thermal influences. For, if the determining
factor in vertical distribution were really the matter of temperature,
we should naturally expect to find the defining line between the
surface and deep-sea faunas to be differently located for different
parts of the earth’s surface, rising in the polar and high temperate
regions, where the surface temperature of the water is itself very
low, and falling in the region of the tropics, whereas, as a matter
of fact, no such condition obtains. Indeed, on the principle gen-
erally entertained, there ought to be in the high northern and
southern latitudes no such thing as an abyssal fauna, inasmuch as
the thermal conditions requisite for its existence would be those
corresponding to the surface fauna as well, a nearly uniform tem-
perature extending through the sea from top to bottom. We should
then expect to meet with the characteristic deep-sea forms of corals,
brachiopods, vitreous sponges, echinoderms, &c., seemingly indica-
tive of a low temperature, in the littoral region, but, as is well
known, they do not occur there, although they are sufficiently
abundant in deep water. It is true that certain animals occurring
in the deeper parts of the warm seas are known as surface forms
only in the Arctic waters; but these are inconsiderable in number,
and in the main uncharacteristic, so that they can scarcely be con-
sidered as a link uniting the littoral with the deep-sea faunas; ina
general way the two are as sharply defined in the Arctic Seas as
anywhere else. But, if it is not the matter of temperature that is
principally involved in the formation of a deep-sea fauna, what is ?
The question does not, perhaps, at the present moment admit of a
definite solution; but a suggestion thrown out in this direction by
Professor Fuchs deserves careful attention. After reviewing the
possibilities that may arise from such proximate causes as differences
in the chemical characters of the water, the quantity of absorbed
air contained in it, and currental motion, all of which must assuredly
be of insignificant import, this eminent authority arrives at the con-
clusion that the only factor which can, in any material way, affect’

118 GEOGRAPHICAL DISTRIBUTION.

vertical distribution is light. It is claimed in confirmation of this
view that the limit of light-penetration in the oceanic waters, as fixed
by Secchi, Pourtalés, and Bouguer, corresponds closely with the
forty to fifty fathom line, marking the upper boundary of the deep-
sea fauna, or, more strictly, the line separating the littoral from the
deep-sea fauna. Below this line, therefore, the fauna is one of dark-
ness, and above it, except in so far as certain animal groups may be
nocturnal in their habits, one of light. In support of this proposi-
tion Professor Fuchs emphasises the fact that, ‘‘ with their character
of animals of darkness, numerous peculiarities in the organisation
and nature of the deep-sea animals agree. Thus it is known that very
many deep-sea animals either have uncommonly large eyes, after
the fashion of nocturnal animals, or are completely blind; it is also
well known that they are, for the most part, either pale and colour-
less, or unicolourous, and that varied colouration is exceedingly sel-
dom met with among them; and, finally, it is likewise well known
that a very large proportion of deep-sea animals, in many groups,
indeed the majority, are vividly luminous. This last peculiarity is
of special importance, for it is clear that luminosity can be of con-
sequence only to such animals as are destined to live in darkness,
and, in point of fact, scarcely any luminous animals are known to
us from the littoral region.”

While it may, perhaps, be admitted that temperature is not the
only, or even principal, agent in determining distribution, it must,
nevertheless, be confessed that certain grave objections present
themselves to the theory which looks upon light as the determin-
ing factor; indeed, the objections are much of the same kind as
those which have been urged against the thermal theory. If the
fact is surprising that corals do not descend below the one hundred
and twenty foot line, when the temperature for a very considerable
distance beyond that point is still above the normal required by
them, is it not perhaps equally surprising that they should be
limited at this point at all, seeing that the penetration of light ex-
tends to fully double or treble the depth, or, as has been more re-
cently shown by MM. Fol and Sarasin in the case of the Mediterra-
nean Sea, to even ten times that depth? Can it be rationally
conceived that such lowly organisms, devoid of special visual or-
gans, can be so affected by the conditions of light and darkness as
not to be able to endure that amount of obscurity which distin-

PELAGIC FAUNA. 119

guishes the zone immediately underlying the twenty fathom line ?
This scarcely appears possible. The extended range of a very
large proportion of the animal forms entering into the composition
of the littoral fauna, and the extreme rarity of instances in which
limitation is so marked as to render most effective the difference
between light and darkness, argue strongly against the notion of
the ail- paramount influence of light as affecting distribution. This
objection to the views advanced by Professor Fuchs, as opposed to
the doctrine of thermal limitation, is further strengthened by the
fact which has been noted in the case of many animal groups (e. g.,
the Brachiopoda) that the vertical range of surface forms is on an
average greater in the boreal and hyperboreal regions—i. e., where
the temperature of the water is more nearly uniform—than in the
more centrally located regions, where a much broader variation in
the temperature of the water manifests itself. It is true, as has
been urged by Professor Fuchs, that the littoral fauna is largely
dependent for its development upon the existence of coral reefs
and coast-binding shell-banks; but in how far this association is
connected with the presence or absence of light, still remains to
be determined. On the whole, while it may be assumed that we
are still largely ignorant of the fundamental facts underlying dis-
tribution, it appears more than likely that not a single cause, but
a combination of causes, is operative in bringing about the general
result. That the deep-sea fauna is a fauna of darkness must be
admitted; but this is so from the necessity of the case rather than
a matter of choice resting with the animals composing it.

A singular correspondence has been noted as existing between
the pelagic (surface) oceanic fauna and the fauna of the oceanic
bottom (abyssal)—a correspondence that has likewise been attrib-
uted by some to a condition of darkness by which the different
organisms are supposed to be governed. To what exact degree the
members of this animal assemblage are nocturnal in their habits, or
constitute true animals of darkness, the observations are not suffi-
ciently far advanced to permit of a general conclusion being ar-
rived at.

Pelagic Fauna.—Under the designation “ pelagic” may be in-
cluded those forms of life which habitually pass their existence on
the free expanse of the ocean, and which only on accidental occa-
sions, if at all, visit the continental borders, or descend to the floor

120 GEOGRAPHICAL DISTRIBUTION.

of the sea. Such are the radiolarians, certain foraminifers and in-
fusorians, the siphonophorous meduse (Portuguese man-of-war,
Physalia; Velella, Porpita), winged-shells (pteropods), a limited
number of gasteropods (Atlanta, Ianthina, Glaucus, &c.), cephalo-
pods, and tunicates (Salpa, Pyrosoma). The schizopod and ento-
mostracous Crustacea are numerously represented, while a genus of
hemipterous insect (Halobates) finds a suitable home clinging to the
waves at practically all distances from the land. A number of
fishes, such as the herrings, mackerel, tunny, swordfish, flying-fish
(Exoceetus), flying-gurnard (Dactyloptera), sea-horse, and most of
the sharks, some of which approach the shore during the spawning
season, might be added to this list, and among the Mammalia the
whales and dolphins.

The primary condition governing the existence of a pelagic
fauna is manifestly the development over the oceanic expanse of
vegetable life. This is found, for the most part, in the microscopic
diatoms and the Oscillatorizw, the former of which abound more
particularly in high northern and southern latitudes, frequently, by
their vast numbers, rendering the water thick as soup, and impart-
ing to it a peculiar brownish or blackish tint, the so-called ‘ black
water” of Arctic navigators. In the temperate and warmer seas
the diatoms are largely replaced by the oscillatorians, whose profuse
development is no less remarkable. In the Arafura Sea, between
Australia and New Guinea, the officers of the ‘‘ Challenger” found
the water continuously discoloured during a period of several days’
sail, and giving out the odour of a reedy pond; and in the Atlantic
they ‘‘ passed for days through water full of minute alge (Tricho-
desmium), gleaming in the water like particles of mica.” * It is to
a species of Trichodesmium (T. erythreeum) that is due the peculiar
red colouring frequently seen over stretches of the Red Sea.

Were it not for this profuse vegetable growth the sea would
probably be, in great part, an uninhabited waste. The alge fur-
nish the necessary nutriment to the simpler forms of animal life,
which in turn yield their substances to those more highly organised.
In this manner a true interdependence of conditions, or balance of
life, is maintained. Professor Moseley, however, believes that in
some parts of the ocean the quantity of freely suspended vegetable

* Moscley, ‘‘ Nature,” xxvi., p. 559.

PELAGIC FAUNA. a

growth is not sufficient to maintain the animal life which appears
to be nourished by it, and he suggests that the deficiency may be
made good through a peculiar symbiotic relation which appears to
exist between certain lowly-organised plants and animals. Thus,
many of the radiolarians and comb-bearers (Ctenophora) contain,
embedded in their body-substance, a number of yellow starch-cells,
which Brandt recognises as unicellular alge (Zooxanthelle), and
which are supposed to thrive upon the waste products of the ani-
mal, and to yield to it in turn the compounds elaborated in the
process of its own development. The relation of mutual benefit
which is here stated to exist probably requires further investigation
before it can be accepted as an absolute fact.*

One of the distinctive characters of the majority of pelagic ani-
mals is their transparency, which renders them very nearly invisible
on the surface of the water. The nerves, muscles, skin, and organs
generally, are alike hyaline, although in many instances the liver
has remained unaffected. The protection thus afforded to such
animals as the radiolarians, jelly-fishes, tunicates, and many crus-
taceans, is compensated for in animals less transparent by a colour-
ing which harmonises with that of the open sea. Thus, the pre-
dominating colour is either blue or violet, as we find it in the
Portuguese man-of-war, the Velella and Porpita, and in Ianthina
and Glaucus among the snails. The fishes are principally steel-blue
above and lustrous white underneath, a want of correspondence
which is also manifest in other animal groups. Glaucus, just men-
tioned, whose progression is effected in the manner of the common
pond-snail, ventral surface uppermost, has this side coloured blue,
and the opposite, or dorsal side, silver-white. Exceptional cases
are presented of an extreme brilliancy of colour, as in the copepod
Sapphirhina, which is said to rival in metallic lustre the humming-
birds, and to display the colours of the spectrum with the intensity
of the gleam of the diamond. *®

Most of the pelagic animals, except the lowest, are devoid of a
shell, or, when present, the shell is usually very thin and fragile,

* Professor Hensen estimates that in some parts of the Baltic there are
upwards of 140,000,000 plants (Rhizosolenia, Cheetoceros) in every ten cubic
metres of water, and maintains that this prodigious quantity is produced in
the course of about two months. “ Bulletin of the United States Fish Com-
mission,’’? August, 1885.

{

122 GEOGRAPHICAL DISTRIBUTION.

as in Argonauta, Cleodora, Atlanta, Carinaria, Ianthina, &c. Ab-
normalities of structure, especially in the case of the immature forms
of littoral species, are frequent, leading to such modification of out-
line as to obscure in great measure the general parental relationship,
The supposed young of the conger-eel develop into small transpar-
ent ribbon-shaped fishes, largely devoid of hemoglobin in their
blood, and with an exclusively cartilaginous skeleton; the young
of certain flat-fishes (Platessa) die without ever reaching maturity,
and before the eyes have become asymmetrically placed; and, in
the case of some of the rock-lobsters (Palinurus), the flattened larve
attain to gigantic proportions. Other instances of such abnormal
development might be mentioned. The unusually large size of the
eyes in some of the annelids and crustaceans (Alciops, Coryczeus)
recalls a similar characteristic belonging to many of the deep-sea
forms of life; likewise the total absence, or very rudimentary con-
dition (as in pteropods), of these organs. The power of emitting
phosphorescent light is another feature held in common by many of
the surface forms of life with the fauna of the deep. Pyrocystis
and Noctiluca, amceboid bodies on the border-line between the
Foraminifera and Infusoria, appear to be the principal contributors
to the general oceanic phosphorescence.

A remarkable feature of the pelagic fauna is the vast swarms
or schools in which many of the forms are found, association being
the rule rather than the exception, and the broad expanse over
which the greater number of the types are spread. The genera
are of almost universal distribution, and many even of the species,
of both the higher forms (fishes) and the lowest, are identical over
the most distantly removed quarters of the globe; the polar faunas,
however, which are constituted principally by the crustaceans,
pteropods, and whales, differ materially from the faunas of the
temperate and equatorial belts, lacking largely in the medusa,
the tunicates, and pelagic fishes. The varying salinity of the
oceanic waters appears very sensibly to affect this fauna, whose
distribution is, accordingly, in a measure governed by it. Thus,
the surface-fauna of the Baltic is very meagre, and in the upper
part of the basin, where the waters are nearly fresh, it is reduced —
to little more than a very limited number of crustaceans. Some
of the medusoids, however, as Aurelia and Cyanea, appear to be
but little affected by a deficiency in the salt-supply, and, indeed,

PELAGIC FAUNA. 123

according to Moseley, they would seem to prefer a habitation near
the mouths of fresh-water streams, being seen to crowd up towards
the heads of fjords and inlets. In the Hawkesbury inlet, New
South Wales, the Scyphomcduse were observed by this naturalist
swimming in shoals where the water was so pure as to be quite
drinkable.

Much uncerta‘nty still exists as to the relation which the free
oceanic fauna bears to the fauna of the deep-sea, an uncertainty
due to the difficulty of determining the actual depth whence the
different organisms caught in the net were obtained. Alexander
Agassiz maintains, as the result of experiments made with the
Sigsbee net, the most improved appliance thus far invented for
the purposes of deep-sea exploration, that “the surface-fauna of
the sea is really limited to a comparatively narrow belt in depth
[about fifty fathoms], and that there is no intermediate belt, so to
speak, of animal life between those animals living on the bottom
or close to it, and the surface pelagic fauna.” ‘7 Beyond a depth
of one hundred fathoms nothing was found. On the other hand,
the numerous observations made by Mr. Murray on board the
‘*Challenger,” with appliances less perfect than those used by Mr.
Agassiz, almost conclusively prove that the depth penetration is
very much greater than is here indicated, and that possibly a
direct continuation exists in the case of certain groups of animals
between the pelagic and abyssal faunas. The fact seems to be
pretty satisfactorily established, however, that the true zone of
free oceanic life, or that which is most numerously inhabited, is a
shallow one, and that whatever life extends to great depths is
comparatively restricted.

It would appear that a large proportion, if not the greater num-
ber, of the pelagic animals are more or less nocturnal in their habits,
shunning the glare of daylight, and appearing on the actual surface
only during the hours of evening and night. Such are most of
the pelagic fishes, crustaceans, pteropods, heteropods, and fora-
minifers, which in their hidden depths for a long time eluded the
search of naturalists. The radiolarians, jelly-fishes, and certain
crustaceans, on the other hand, seem to prefer the open daylight,
appearing at all hours on the surface during calms; and the same
is the case with a number of fishes, as the flying-fish and dolphin
(Coryphena). There is thus a perpetual oscillation in this upper

124 GEOGRAPHICAL DISTRIBUTION.

zone of life, which, as dependent upon an excess or deficiency in
illumination, probably does not extend much beyond a depth of
fifty fathoms.

There can be but little doubt that a pelagic fauna antedated all
the faunas of the globe, and that from it, through a long process
of modification and adaptation, have been derived the faunas of
the shore, the abyssal deep, the land-surface, and the various fresh-
waters. The identity, or close resemblance, existing between the
larval forms of many of the most divergent animal groups clearly
indicates the lines along which modification has resulted, for it can
scarcely be conceived, as Professor Moseley well insists, that this
general identity in larval structure could have been brought about
as the result of natural selection after the adult forms had largely
diverged from one another. The earliest traces of a pelagic fauna
are indicated in the rocks of Cambrian age, where, as representative
of it, we find, besides the remains of pteropods, the impressions of
jelly-fishes, which were apparently not very far removed from some
modern Scyphomeduse. The marine animals that are deficient or
lacking in the composition of the pelagic fauna, and not improbably
have always been lacking, are the sponges, alcyonarian corals,
sipunculoid worms, brachiopods, lamellibranchs, and echinoderms.
The true infusorians (Ciliata) appear to be but very feebly repre-
sented, although there is an abundance of the Cilioflagellata.

Nature of the Littoral Fauna.—That the littoral fauna is
either wholly or in great part a derivative of the free oceanic or
pelagic fauna there is every reason to believe. The supposition
that the latter came into existence before the former is at once a
natural one, and is supported, apart from general zoogeological
considerations, by the character of the mutually related littoral
larvee, whose adaptation to a pelagic existence clearly indicates the
nature of their primal condition. There is, further, every reason
to believe that the earliest plants were also largely pelagic, and
that not until these had firmly established themselves as permanent
forms along the sea-border was there developed a shore-fauna. In
exposing themselves to the manifold conditions, such as the break-
ing of the surf, tidal action, shore-wash, attacks of enemies,
which a change of abode entailed upon the members of the pelagic
fauna, these were by force of adaptation compelled to undergo par-
ticular modifications of habit and structure which rendered them

LITTORAL FAUNA. 125

better fitted to their new surroundings. This we see in the defen-
sive armour or encasement with which a very large number of the
shore animals are provided, a character which eminently distin-
guishes them from the inhabitants of the open ocean. The shells,
which are with the latter in most cases very thin and fragile, as in
Atlanta, the argonaut, and the pteropods generally, are in the vast
majority of shore animals thick and resisting, and capable of with-
standing the numerous strains and impacts to which they are sub-
jected.

But the same causes which have been operative in producing
modifications in the pelagic fauna have been influential in bringing
about a no less important series of modifications in the littoral
fauna as well. The intermingling of fresh and salt waters about
the embouchures of rivers, or a deficiency, as in the ice-bound north,
in the salinity of the sea itself, will have gradually paved the way
for the formation or evolution of animal forms destined to live
eventually in fresh water. Hence, the origin in principal part of
the fresh-water faunas. Similarly, frequent exposure to the at-
mosphere beyond the interacting influence of the aqueous medium,
as in the region of ‘‘ between tides,” will have developed a method
of respiration, or respiratory apparatus, other than that which is
dependent for its action upon the presence of water. The remark-
able series of modifications which the Amphibia (frogs, toads, sala-
manders) undergo from their larval condition, when, as inhabitants
of the water, they breathe by gills, to their adult stage, when
respiration is in most cases effected through the intermedium of
lungs alone, most forcibly illustrate the progression which, at least
in one division of the animal series, the vertebrates, has led to
the formation of the air-breathing or terrestrial fauna. But other
instances of adaptation from an aqueous to a terrestrial existence
are not wanting. Many fishes have their gills so modified as
to permit of a very protracted existence on dry land, while, as is
well known, the lung-fishes (Dipnoi) have developed true lungs.
Land-crabs are very abundant in the Tropics, roaming about in the
interior at very considerable distances from the shore. In Japan
they have been observed at an elevation of four thousand feet above
the sea. The remarkable cocoanut crab, Birgus latro, is provided
with a pair of true lungs, developed on the walls of its gill cavities.

Professor Moseley ** thus sums up the relations of the littoral

126 » GEOGRAPHICAL DISTRIBUTION.

fauna: ‘The fauna of the coast has not only given origin to the
terrestrial and fresh-water faunas, it has throughout all time, since
life originated, given additions to the pelagic fauna in return for
having received from it its starting-point. It has also received
some of these pelagic forms back again to assume a fresh littoral
existence. The terrestrial fauna has returned some forms to the
shores, such as certain shore-birds, seals, and the polar bear; and
some of these, such as the whales and a small oceanic insect, Halo-
bates, have returned thence to pelagic life.

‘‘ The deep-sea fauna has probably been formed almost entirely
from the littoral, not in most remote antiquity, but only after food,
derived from the débris of the littoral and terrestrial faunas and
floras, became abundant in deep water. It was in the littoral region
that all the primary branches of the zoological family-tree were
formed; all terrestrial and deep-sea forms have passed through a
littoral phase, and amongst the representatives of the littoral fauna
the recapitulative history, in the form of series of larval conditions,
is most completely retained.”

Lake Faunas.—It would appear that in all large lakes three
distinct faunas can be recognised: 1. The littoral fauna, comprising
the animals of the shore-line, which do not habitually descend to a
much greater depth than fifteen or twenty feet. 2. The deep fauna,
whose representatives live along the floor of the lake, at depths
usually exceeding sixty to a hundred feet, a limited number of
forms occasionally rising to the surface; and 3. The pelagic fauna,
whose members occupy the free surface of the lakes, rarely or never
reaching the shore-line or descending to the bottom. The zone
inhabited by the last measures from fifty toa hundred metres in
depth.

Our general knowledge respecting the pelagic fauna is still very
limited, and is based almost exclusively upon observations made
upon the European lakes. From these it would seem that the
fauna is a very restricted one, consisting, as far as is known, of
some twenty-five species of entomostracous crustaceans (ostracods,
cladoceres, and copepods), a fresh-water mite (Atax crassipes), about
six species of rotifers, and a limited number of infusorians. No
lake has thus far yielded all these forms, and the majority of lakes
are largely deficient. Between the years 1874 and 1878 Forel *° ob-
tained in the Lake of Geneva only eight species: Diaptomus castor,

LAKE FAUNAS. 127

Cyclops (sp. undet.), Daphnia hyalina, D. mucronata, Bosmia lon-
gispina, Sida crystallina, Bythotrephes longimanus, Leptodora hya-
lina. Of the total number of twenty-four species which were ob-
tained by Pavesi® from the Italian lakes, belonging almost exclu-
sively to such genera as occur in Lake Geneva, only four (Daphnia
hyalina, D. galeata, Bosmia longispina, Leptodora hyalina) are
known to inhabit the Lago Maggiore, and an equal number the
Lago di Como. The Lago d’Iseo, on the other hand, has ten spe-
cies, and Orta and Mergozzo eleven each. As far as the Crustacea
are concerned, the Swiss lakes appear to be less rich in point of
species than the Scandinavian; but they alone, with the adjoining
lakes of Annecy and Bourget, in Savoy, have thus far yielded any
variety of forms of lower organisation than the articulates. M.
Imhof’s investigations have brought to light, as constituents of the
Swiss pelagic faunas, two species each of flagellate (Dinobryon)
and cilioflagellate (Peridinium, Ceratium) infusorians, two species
of true infusorians (Epistylis lacustris, Acineta elegans), which live
attached on the crustaceans, and the six rotifers already referred to,
belonging to the genera Conochilus, Asphanema, Anureea, Triarthra,
and Polyarthra. Doubtless some of these forms will also be found
in the more northern and southern lakes.*

The general characters common to the animals of the pelagic
region, which are the outcome of their particular mode of life, are
thus briefly summarised by Forel: ‘‘ They must swim incessantly,
without ever being able to rest upon a solid body, and, instead of
any organ of adhesion, they possess a highly developed natatory
apparatus; their specific gravity, which is nearly the same as that
of the water, enables them to swim about in the water without any
great muscular exertion. They are rather sluggish animals, and
escape the enemies that pursue them rather by their transparency
than by their activity; they are, indeed (and this is their character-
istic peculiarity), perfectly transparent, like crystals; and only their
strongly pigmented black, brown, or red eye appears distinctly.
This nearly perfect transparency of the pelagic animals may be re-
garded as a mimicry acquired by natural selection; only the animals

*<*¢ Ann. and Mag. Nat. Hist.,’? December, 1883; January, 1884. Since
the above was written Imhof has identified several of the Swiss crustaceans,
rotifers, &c., in the lakes of Alsace-Lorraine. ‘ Zoologisher Anzeiger,” De-
cember, 1885.50

128 GEOGRAPHICAL DISTRIBUTION.

which are as transparent as the medium in which they live have
held their own.”

The lacustrine pelagic animals perform daily vertical migrations
of the same character as has been noted in the case of the oceanic
pelagic fauna, descending to the regions of obscurity during the
day-time, and ascending by night. The animals appear to shun
the light of the sun, and even of the moon, and hence retire to a
depth probably not far from the limits of light penetration; the
fauna is, therefore, one of darkness. The greatest depth whence
specimens were obtained by Forel in Lake Geneva was about one
hundred and fifty metres; but at this depth only Diaptomus was
found. At a depth of fifty metres, in the Lago d’Orta, Pavesi
found a very profuse fauna, represented by seven species; in the
Lago d’Iseo, at five, fifteen, and thirty metres, the catch appears to
have been exceedingly abundant (‘‘la pesca fu prodigiosamente ab-
bondante”); but, at one hundred metres, where the temperature of
the water was 19° C., as compared with a surface temperature of
23° C., the fauna was decidedly scanty, although five distinct forms
were obtained.

To what extent the downward extension of the pelagic fauna is
governed by conditions of temperature, or in how far this limitation
is dependent principally upon the presence or absence of light as a
determining factor in the evolution of plant life, still remains to be
ascertained. Forel, in 1874, found that paper sensitised with chlo-
ride of silver was still acted upon by the diffused light of the Lake
of Geneva at a depth of about forty-five metres in summer and one
hundred metres in winter, while ordinary shining objects disap-
peared from view at a depth of sixteen to seventeen metres. Asper,
in August, 1881, obtained positive results through the use of plates
sensitised with an emulsion of bromide of silver at a depth some-
what exceeding ninety metres in the Lake of Zurich; and more re-
cently (1884—’85) Fol, Sarasin, Pictet, and others, have been able
to detect the penetration of light in Lake Geneva to a maximum
depth (in winter) of two hundred metres. In summer the penetra-
tion is considerably less. Fol and Sarasin have also demonstrated
that, in the Mediterranean, the solar rays penetrate to a depth nearly
double that to which they were found to descend in the Swiss lakes,
or to four hundred metres, and that at a depth of three hundred
and eighty metres the intensity of light is as great as in Lake

LAKE FAUNAS. 129

Geneva at one hundred and ninety-two metres. At this depth,
however, the impression produced upon the sensitised plates was
of no greater value than that which would have been produced,
under ordinary conditions, on a clear night, without a moon.

A remarkable feature of the lacustrine fauna is the very broad
distribution of most of the species. Not only is there a general
resemblance between the pelagic faunas of all the European lakes
that have thus far been examined, from Scandinavia to Italy, and
from Italy to Bohemia and the Caucasus, but a strict identity, at
least as far as the species of Entomostraca are concerned. The
species that occur in the one lake are also the species of the other
lakes, although the respective littoral and deep faunas may be
largely distinct. Further, it would appear that the same species
are constituents of the pelagic faunas of American lakes as well,
and not improbably make up the greater part of them. Professor
8. I. Smith,” in his investigations of the fauna of Lake Superior,
determined the presence, in the surface waters, of Daphnia galeata
and Leptodora hyalina, common forms in the lakes of both Southern
and Northern Europe, and of Daphnia pellucida, which was de-
scribed by Miller as a pelagic inhabitant of some of the Danish
waters.

As to the origin of the pelagic fauna little positive is known.
That it is not a direct derivative of the different littoral faunas is
very nearly certain, for were this the case we should expect to meet
with largely differing assemblages of pelagic forms im all lakes
where the littoral or deep faunas likewise differ; but, as has been
seen, this is not the case. Yet there can be little or no question
that it really represents a modification of some primary shore-fauna,
whose members, through force of circumstances, were compelled
to adapt themselves to new conditions of existence. The supposed
method of its differentiation and further distribution is thus indi-
cated by Forel: ‘‘I believe we must find the cause of the differ-
entiation of the pelagic fauna in the combination of two different
phenomena — namely, the daily migrations of the Entomostraca,
and the regular local winds of the great lakes. It is well known
that on the borders of great masses of water two regular winds
prevail, one of which blows at night from the land towards the
water, the other by day from the water to the land. The nocturnal

animals of the shore-region, which swim at night at the surface,
Led
7

130 GEOGRAPHICAL DISTRIBUTION.

are at this time driven towards the middle of the lake by the sur-
face-current of the land-winds, sink during the day, being driven
away by the light, to the deep water, and thus escape the surface-
current of the lake-winds, which would otherwise have carried
them again to the shore. Constantly driven farther every night,
they remain confined to the pelagic region, as they are not carried
back again during the day. Thus a differentiation takes place by
natural selection, until at last, after a certain number of genera-
tions, there remain only the wonderfully transparent and almost
exclusively swimming animals which we know. When this differ-
entiation has once taken place, the pelagic speciés is conveyed [in
the condition of resting eggs] by the migratory water-birds from
one country to another, and from one lake into another, where it
reproduces its kind if the conditions of existence of the medium
are favourable. In this way we may find the pelagic Entomostraca
in lakes which are too small to possess the alternation of winds,
the animals having been differentiated by the action of the winds
in other larger lakes.”

It might, however, be asked with Pavesi, if the general uni-
formity of pelagic faunas has been brought about through a method
of distribution such as is here indicated, how has it happened that
some lakes should be so largely deficient in pelagic forms as com-
pared with other, and nearly contiguous, lakes? The lakes of
Northern Italy may be taken in illustration of a condition of this
kind. Seeing that identical forms have been scattered to such
widely separated quarters of a continent, as Italy, Scandinavia, and
the Caucasus, it certainly appears a little surprising that immedi-
ately adjoining districts should have been so irregularly stocked
with the distributed material. It might, however, be conceived
to be a matter of accident, and, indeed, at first sight the condition
appears to be more in the nature of a support to the theory stated
than as an argument against it. But if accidental conditions of
this kind have happened, why has it not also accidentally happened
that some of the lakes should have retained a fauna, formed through
modification of their own particular littoral or deep fauna, distinct
from that of any other lake ? Still, the objection here raised is not
an insuperable one, and offers much less difficulty in the way of the
partial solution of the problem than does the circumstance of the oc-
currence of identical forms in the lakes of Europe and North America.

LAKE FAUNAS. Aisi

Deep Faunas of Lakes.—The most systematic and thorough
investigations that have been made into the nature of deep lacustrine
faunas are those of Forel upon the fauna of Lake Geneva.** As the
result of the observations of this naturalist it would appear that
the abundant fauna of the floor of this lake comprises representa-
tives of nearly all the primary divisions of fresh-water—inhabiting
Invertebrata, and that even a fair proportion of the secondary
groups are also represented, although by a very limited number of
species in nearly all cases. Included in the lowest forms are sey-
eral ameebe, and Epistylis, Opercularia, and Acineta among infu-
sorians. The hydroids are represented by the common brown hydra
(Hydra rubra—to one hundred metres), and the rotifers by Flos-
cularia. Three orders of worms are indicated—nematoids, cestoids,
and turbellarians—and two of annelids proper, the hirudines and
chetopods (Lombriculus, Tubifex, &c.}. The turbellarians (Pla-
naria, Mesostomum, Dendroccelum) have no less than eleven species,
one of which, Vortex Lemani, is found at all depths between fifteen
and three hundred metres. A cestoid was dredged from a depth
of two hundred and fifty-eight metres. The crustaceans are repre-
sented by a limited number of species belonging to the amphipods
(Gammarus cecus), isopods (Asellus cecus), cladoceres (Lynceus),
ostracods (Cypris, Candona), and copepods (Cyclops, Canthocamp-
tus). Other articulates are four or five species, and as many genera,
of arachnids (Arctiscus, Hydrachnella, &c.) and the larve of some
tipuliform insects. The limited number of mollusks inhabiting the
depth is not a little remarkable; of the lamellibranchs there is the
single genus Pisidium, with about three species, and of the gastero-
pods only the genera Limnea and Valvata. Although the Unioni-
dee (Anodon) are very abundant in the littoral fauna, they are com-
pletely absent below. One species of Limnza (L. abyssicola) was
found to be sufficiently abundant at a depth of two hundred and
fifty metres, a circumstance to which Forel calls attention as indi-
cating the readiness with which an air-breathing mollusk can ac-
commodate itself to conditions largely at variance with those which
are considered necessary to conform to certain structural peculiari-
ties. *

* When brought to what might be considered its proper position, the sur-
face of the water, the mollusk almost immediately adapted itself to the new
conditions of existence, apparently without undergoing any inconvenience.

1382 GEOGRAPHICAL DISTRIBUTION.

Although the fauna, taken as a whole, may be said to possess
certain special characters, yet, broadly considered, it is only the
representative, by slight modification, of the fauna of the littoral
zone. It possesses no really well-defined or abnormal features of
its own. Most of the forms are of small size, and a number of
them, whose surface representatives are active and good swimmers,
appear to have taken to sluggish habits; neither Cyclops nor Lynceus
would rise when placed in an aquarium. Blindness is exceptional,
and it isa surprising fact that the animals suffering from this defect
(Gammarus cecus, Asellus cecus) are comparatively shallow-water
forms (thirty metres), whereas those living at the greater depths,
down to three hundred fathoms, are well provided with visual
organs. The faunas of different zones of depth do not appear to
differ sensibly from one another, except in the elimination or excess
of a number of species. The greater number of these would seem
to be distinct from their analogues of the littoral zone.*

Many of the species found in Lake Geneva are identical with
forms found in the other Swiss lakes, and in the lakes of Savoy, as
identified by Imhof, and there is good reason for supposing that
a general analogy, if not absolute identity, unites the different deep
lacustrine faunas of the same region. Professor Smith obtained
from deep water (exceeding fifteen fathoms) in Lake Superior™
Hydra carnea (from eight to one hundred and forty-eight fathoms),
a Pisidium (from four to one hundred and fifty-nine fathoms), several
species of worms (Senuris, Nephelis, Tubifex, &c.), the larve of
various tipulids and ephemerids, and among crustaceans Mysis
relicta and Pontoporeia affinis (from shallow water to one hundred
and fifty-nine fathoms). The last two, which were also found by
Stimpson in Lake Michigan, are forms belonging to Lake Wetter
in Sweden, supposed by Lovén to have been derived by modifica-
tion from marine species.

* So stated by Forel in his report of 1876, although in 1874 ke and Plessis
appear to have maintained the opposite view.

PARLE EL

GEOLOGICAL DISTRIBUTION.

The succession of life.—Faunas of the different geological periods.

THERE is no fact more patent in the history of the organic
world than that there has been from first to last a progressive evo-
lution from lower to higher forms in the chain of beings that suc-
cessively peopled the earth’s surface. Casting our eye back over
the vast series of rock deposits which together constitute the fossili-
ferous scale of geologists, from the Cambrian to the Post-Pliocene,
and which together have a maximum development of probably
not less than two hundred thousand feet (or forty miles), we re-
mark along the most ancient horizon the traces of animals which
bespeak the organisation of some of the lowest forms of life with
which we are at present acquainted; in the middle distance we
note the appearance of forms whose organisation marks a decided
advance upon that of their predecessors; and, finally, in the fore-
ground, we are brought upon the threshold of those highly com-
plicated forms which to-day people the surface of the earth. The
simpler forms of life came into existence first; the most complex
last. It must not be implied, however, that with the progressive
and steady evolution of higher forms there has been an equally
progressive destruction or elimination of the forms of lower or-
ganisation; both have kept pace with each other, so that, at the
present day, although innumerable groups have completely disap-
peared, the lowest is found flourishing side by side with the highest.
This inter-association of lower and higher forms has manifested it-

134 GEOLOGICAL DISTRIBUTION.

self in all the geological formations that are known to us, from the
Cambrian period to the present day, and there can be no doubt
that, were a fossiliferous formation discovered of older date than
the Cambrian, or immediately underlying it, we should find pre-
cisely the same juxtaposition, although to a more limited extent, of
organisms of higher and lower development. Only then when we
could fathom the first-born deposit, or trench upon the period
when life first came into existence, would we, in.all probability, be
circumscribed in our survey to animals exhibiting a nearly uniform
low grade of organisation. Such a point has probably not yet
been reached, or, if reached, its existence can only be indicated
with doubt, since the oldest rock deposits (the Laurentian) into
whose composition an organic element unquestionably largely en-
tered have lost all or nearly all traces of their primary fossiliferous
character. With this wholesale obliteration have, consequently,
disappeared the traces of the earliest and most primitive types of
life-forms.

If Eozoon and Archeospherina, from the Laurentian limestones,
be considered actually to represent organic forms, as is maintained
by many prominent geologists and naturalists, then, indeed, are we
presented with a large series of deposits in which apparently all
the organic elements belong to one uniformly low type—the type
of the Foraminifera—not yet the iowest, but very nearly it. But
even granting the animal nature of the two structures here indi-
cated, it would yet be very unsafe to affirm that they represent
the only forms of life that tenanted the earliest seas; multitudes
of other forms may have flourished and perished, and left no
traces behind them, or had their traces completely obliterated at
some remote subsequent period. We should then be no wiser for
their existence. The succeeding Cambrian period ushers in with
it such a host of multiform beings—beings of comparatively high
organisation—that it becomes almost impossible to conceive that
their ancestry should date back only to a period so little removed
from the Cambrian as the Laurentian, unless, indeed, the hiatus
separating the Laurentian from the Cambrian is very much greater
than is indicated by its stratigraphical position. But if the an-
cestral forms of the Cambrian stock already existed in the Laurentian
seas, what has become of their remains? Why is it that in these
oldest so-called fossiliferous rocks we meet with only Eozoon and

CAMBRIAN FAUNA. 135

Archeospherina? Surely it could not have been that there was
such a disposition of the remains as to leave nothing but these two
forms belonging to the lowest type. It appears far more plausible
to assume with those who uphold the mineral nature of Eozoon
and Archeospherina that we have no traces of this ancient pre-
Cambrian fauna remaining, and that, consequently, the destruction
was complete. How far back beyond the Laurentian the root of
the present existing chain of organisms may have extended it is
impossible even to conjecture.

Cambrian Fauna,—It is certainly a surprising fact, whichever
way it be considered, that, with the formation bringing the first
unequivocal evidences of organic life, we should meet with that
multiplicity and variety which characterise the faunal assemblage
of the Cambrian period. Most of the greater divisions of the ani-
mal kingdom, possibly not even excepting the vertebrates, were
there represented, and most of these already in the lowest or
oldest deposit — protozoans, ccelenterates, echinoderms, worms,
articulates, and mollusks. And more than this, some of these
groups were already represented by a full, or nearly full, com-
plement of the orders that have been assigned to them by natu-
ralists, and which include all the various forms that have thus
far been discovered as belonging to the groups. Thus the Cam-
brian echinoderms are represented by forms belonging to three
out of the six usually recognised orders—the Cystidea, Crinoidea
(ocean-lilies), and Asteroidea (star-fishes). The last two have repre-
sentatives living at the present day, whereas the former is entirely
extinct. We have here, then, the most ancient ocean-lily and star-
fish (Palasterina), and it is interesting to note what distinct rela-
tions these two forms hold to their modern representatives. While
the Crinoidea attained their maximum development in the seas of
the Paleozoic period—Silurian, Devonian, and Carboniferous—since
which time they have been pretty steadily declining, until at the
present moment they are represented by scarcely more than a half-
dozen distinct generic types, the Asteroidea have been just as stead-
ily increasing, and, indeed, attain their maximum development in
the modern seas.

It may appear at first sight anomalous how two groups, so widely
dissimilar from each other, and having such varying developments,
should have appeared simultaneously in the same period of the

136 GEOLOGICAL DISTRIBUTION.

earth’s geological history, the Cambrian. But it must be borne in
mind that in the Cambrian formation we have only what is seem-
ingly the oldest fossiliferous formation, and that the ancestral forms
of both ocean-lilies and star-fishes lie buried in rock deposits of
undeterminably older age. If, on the hypothesis of evolution, we
uphold the inter-derivation, or derivation from one another, of these
two forms, then it is but fair to assume that the crinoid, which is
structurally the lowest, appeared at a period considerably anterior
to the star-fish, which must have required for its specialisation a
no inconsiderable lapse of time. And it is a singular fact, and one
strikingly confirmatory of this view of relationship, that we have in
both these forms certain peculiarities of structure which effect a
sort of transition from the one to the other. Thus, in some of the
fixed crinoids the plume or tuft separates.from the column after
a certain period of existence, and then leads an independent exist-
ence, to all appearance a stellarid (the Comatula). Conversely, the
officers of the late ‘‘Travailleur” deep-sea dredging expedition
obtained off the coast of Spain, and from depths respectively of
nineteen hundred and sixty and twenty-six hundred and fifty
metres, two individuals of a new genus of star-fish (since named
by Perrier Caulaster peduncularis), which exhibited on the dorsal
surface a true peduncle, demonstrated to be absolutely homologous
with the stalk of the crinoid. Yet, despite this obvious relation-
ship, it is not a little surprising that no pedunculated star-fish has
thus far been found fossil, nor any comatulid crinoid to antedate
the Jurassic period (Antedon).

The Cambrian Mollusca comprise representatives of five of the
six classes that now inhabit the seas, namely, the Brachiopoda,
Acephala, Pteropoda, Gasteropoda, and Cephalopoda. Here again,
therefore, we have an apparent simultaneous appearance of lower
and higher forms; but, as before, we must look to a much earlier
period for the ancestral traces, if any have been preserved, of the
first or most primitive type. The genetic relationships of these
various molluscan groups cannot, in the present state of the science,
be determined with any degree of certainty; but, if a low degree
of organisation indicates antiquity, which certainly appears to be
the case with many groups of animals, then it may be fairly assumed
that the Brachiopoda were the first to appear. It is a surprising
fact in the history of these animals, and one which is, perhaps, not

CAMBRIAN FAUNA. 137

repeated to the same extent in any other group, that while hosts of
genera, and even complete families of this order, which flourished
in the seas intermediate in time between the Cambrian period and
our own day, should have successively disappeared, a few individual
types seem to have survived from first to last, without having un-
dergone any essential modification of structure. Thus, the Lingula,
or Lingulella, of the Cambrian rocks is but very little, if at all, dif-
ferent from the existing Lingula, and it has indeed been considered
doubtful by some authors whether even specific characters could be
assigned to distinguish some of the earlier from the later forms,
separated by an interval of millions of years. The same persistence
of type is represented in the genus Discina.

Side by side with these lower molluscan types, but appearing at
a somewhat later period, the Upper Cambrian, we find, as has al-
ready been stated, forms belonging to the highest order, the Cepha-
lopoda (Orthoceras, Cyrtoceras), another apparent contradiction to
the doctrine of progressive higher development. Considering the
group of the cephalopods by itself, however, we observe that its
earliest types belonged to the lower of the two divisions into which
the cuttle-fishes have been divided—the tetrabranchiate, or four-
gilled order—a division to which the somewhat later appearing,
and now probably disappearing, Nautilus also belongs. These
primitive cephalopods were succeeded in time by other members of
the same order—Gyroceras, Nautilus, Goniatites—until the Tri-
assic period was reached, when the first dibranchiate form, Belem-
nites, appears. From this period down to the close of the Meso-
zoic era both the two-gilled and the four-gilled forms occur in such
abundance that it would be almost impossible to state to which
group belonged the preeminence. But in the meanwhile a general
alteration and succession in the representative cephalopod type had
been taking place. The early forms already mentioned, Orthoceras,
Gyroceras, Cyrtoceras, and their allies, belonging to the family of
the Nautilide, are succeeded in the Triassic period, where their last
traces (excepting Nautilus) are to be met with, by the members of
the more complicated group of the Ammonitide, whose earliest
precursors (three or more species from the Carboniferous formations
of India, and a solitary species from the Carboniferous of Texas)
would seem to have been foreshadowed by Goniatites, a type struc-
turally intermediate between the Nautilide and the Ammonitide.

138 GEOLOGICAL DISTRIBUTION.

Similarly, in the case of the Cephalopoda dibranchiata, the Belem-
nitidz are succeeded by forms more nearly resembling the cala-
maries, or cuttle-fishes (Teuthidz), of to-day, whose remains are
found already in the Jurassic deposits (Onychoteuthis, Teuthop-
sis, Belemnosepia). With the beginning of the Tertiary period *
we note the final disappearance of the varied group of the Ammoni-
tide, and with them the last traces of all but one of the lower
or four-gilled order of cephalopods. The single exception is the
Nautilus, which, as a persistent type, almost unaltered from the
Silurian to the present period, alone survives to contest the seas
with the members of the higher or dibranchiate order.

The predominant Mollusca of our modern seas, the Gasteropoda
and the Acephala, were but feebly represented in the seas of the
Cambrian period; but it seems not improbable that some of the
earliest forms—e. g., Capulus, Pleurotomaria, among the snails—
belonged to types absolutely identical with those living at the
present time. It is not until we have completely passed over the
Paleozoic era, which, so far as the Mollusca are concerned, may be
said to constitute the age of the Brachiopoda, that these two orders
of shell-fish attain any special significance. From the beginning of
the Mesozoic era onward they steadily crowd the deposits with their
remains, until, finally, with the Tertiary formations, and the forma-
tions succeeding these, they constitute the most characteristic and
most important invertebrate landmarks to the geologist and paleon-
tologist.

It has been contended, and with apparent force, that the irregu-
lar appearance in time of the Mollusca—z. e., the almost simultane-
ous introduction of forms belonging to both the lowest and the
highest orders, and the final supremacy in the existing seas of the
type of the Acephala, a group of mollusks inferior in organisation
to the Cephalopoda, the Gasteropoda, and the Pteropoda—is in-
compatible with the doctrine of evolution, which, as argued, re-
quires for its confirmation the introduction first of the lower forms,
the development from these of the more advanced, and, ultimate-
ly, the appearance of those that are most perfect or specialised in
structure. It must be recollected, however, that, as far as the al-
most simultaneous introduction of lower and higher forms is con-

* A species from the Lower Tertiary of California.

CAMBRIAN FAUNA. 139

cerned, the obstacle is more apparent than real, for, as has already
been insisted upon, it is impossible to determine how far back be-
yond the Cambrian, or first unequivocally fossiliferous formation,
life may have already existed, and, consequently, to what very
ancient period the ancestry of the molluscan type may extend. As
a matter of fact, the most ancient mollusk, the Lingula, or Lingu-
lella, is almost the lowest in structure of any with which we are
acquainted, and if in the rock deposits we meet with its remains
but barely antedating those of the very much more highly organ-
ised Orthoceras, we have yet strong grounds for concluding that its
first appearance was very much earlier, only that, through the gen-
eral obliteration of all remains in the preceding geological period,
direct evidence to that effect has been lost. As to the other objec-
tion, that the predominant forms persisting at any given epoch
should be those whose structure manifests the highest development,
it may be remarked that the evolutionary force requires no such
result as the outcome of its operative action. It is among such
forms as, in their mutual relations to their surroundings, whatever
these may be, are best adapted or fitted for combatting the nu-
merous elements that constantly interpose themselves in the path
of existence, that we must look for examples of greatest persistencé
and development—for the survivors in the struggle for existence.
Hence, while the highest developed forms in any given series of
animals will present themselves in or about the period most re-
moved from the birth of that series, yet it need not follow that
the higher series will ultimately outlive, or even predominate over,
the representatives of a lower parallel series of the same class of
animals, whose fitness for struggling in the battle for existence is .
not infrequently vastly superior to that of the higher class. We
need not be, therefore, surprised at finding, in a given class of ani-
mals, some of the more perfect forms disappearing from the world’s
horizon before the less perfect, and these last, consequently, the
survivors in the general battle for hfe. But, while no general law
can be formulated regarding the disappearance, as conditioned by
the degree of perfection, of the various series of a given class of
animals, or, regarding their relative development in any one period
of the earth’s history, the law of appearance or succession already
stated—i. e., the introduction of lower forms before those of a
higher order—can very generally be maintained.

140 GEOLOGICAL DISTRIBUTION.

An objection to the evolutionary doctrine, similar to that which
has been drawn from the distribution of the Mollusca, is also fur-
nished by the articulated animals, or, more particularly, by the class
of the Crustacea. The members of this class boast of a lineage, as
far as has yet been determined, very nearly, if not fully, as ancient
as that of the Mollusca, one extending back to the earliest Cambrian
period. But, while the most ancient mollusks with which we are
acquainted belong in great part to orders, families, and even genera,
whose representatives still flourish in the existing seas, the most
ancient crustaceans, or at least the majority of them, the Trilobita,
have long since become totally extinct; hence the impossibility of
determining their true relationships. However uncertain or obscure
this relationship may be, whether it is with the Phyllopods, as
claimed by some, or, what is much more likely, with the Xiphosura.
(king-crabs) and arachnids, as argued by others, there can be no
doubt, if homologies of structure can be relied upon, that the mem-
bers of this group of animals represent a high grade of structural
organisation, and especially if the period of their appearance is
taken into consideration. But here, just as in the case of the
Mollusca, we have the strongest evidence for concluding that their
earliest appearance dates far beyond the Cambrian period, as is
proved almost conclusively by the simultaneous appearance in the
oldest Cambrian strata of some of the simplest and most compli-
cated trilobitic forms, Agnostus and Paradoxides, which are at the
same time also among the smallest and the largest forms of the
entire order. A further evidence of the pre-Cambrian antiquity of
this group is furnished by the circumstance of the abundance in
which the earliest remains are found, an abundance which, though
perhaps not equal to that characteristic of the succeeding Silurian
and Devonian trilobitic faunas, is yet sufficient to impress a dis-
tinct individuality upon the fauna of the period. While with
the Cambrian trilobites we find associated other forms of crusta-
cean animals, such as the phyllopods (Hymenocaris) and ostracods
(Primitia, Leperditia), the highest members of the class, the Deca-
poda (crabs and lobsters), appear not to have been as yet evolved.
Indeed, it is not until the entire Silurian period and a considerable
portion of the Devonian are passed that we mect with an example
of the ten-legged order of crustaceans. Barely had these higher
forms asserted themselves on the field of life ere a decline in the

CAMBRIAN FAUNA. 141

supremacy of their predecessors is made manifest. With the mid-
dle of the Devonian period the beginning of the trilobitic decay
becomes apparent, and, after the close of that period, 7. ¢., in the
Carboniferous, less than a half-dozen types remain, and even these
are of comparatively rare occurrence. At the close of this last-
named period the trilobites disappear totally and forever from the
scene.*

Broadly locking over the Cambrian fauna, we find it to be dis-
tinguished by two important features. One of these is the fact
that it is entirely destitute of both land and fresh-water forms, or
such as are strictly adapted to breathing directly the oxygen of the
atmosphere or that of fresh water. All the forms thus far encoun-
tered are, as far as we know, of a strictly marine nature. The ab-
sence of land animals will scarcely appear surprising in view of the
complete, or nearly complete, absence of a land vegetation, and the
correlative want of the nourishing material requisite for that charac-
ter of organisms. The absence of fresh-water forms is not so readily
accounted for, unless it be that there were formed at that time no
fluviatile or lacustrine accumulations of sufficient magnitude to have
left their traces behind them. It is not impossible, however, that
some, or even many, of the recognised marine fossils, or such as
have a marine habit, of the Cambrian formation, are in reality
estuarine or brackish forms, as it can scarcely be conceived that all
the deposits that were formed at the mouths of the ancient rivers
should have been so totally destroyed or covered over as to have
left absolutely no vestiges of their former existence. Doubtless,
some of these have been preserved, along with their contained fos-
sils, although the exact nature of such deposits may be disguised
from us by reason of our imperfect knowledge concerning the true
habits of their representative organisms. Nor would it be abso-
lutely safe to affirm that some of these organisms, undistinguishable
from what at the present day are indisputably marine types, may
not in reality have been of a purely fresh-water habit in those early
days.

The other distinguishing feature of the Cambrian fauna is the

* Shumard has described representatives of the genera Phillipsia and
Proetus in deposits of the Sierra Madre, of the Southern United States, claimed
to belong to the Permian period; the determination of age may be considered
to be very doubtful, however.

142 GEOLOGICAL DISTRIBUTION.

absence of positive indications of the existence of vertebrated ani-
mals. The only objects that have thus far been described as per-
taining, with any show of probability, to the members of this highest
division of the animal kingdom, are the singular bodies known as
conodonts, which, in the opinion of their discoverer, Pander, and
of some other naturalists, represent the teeth of fishes belonging to
the order of the myxinoids (hags and lampreys), with the exception
of the lancelet (Amphioxus) the lowest of the entire class of Pisces.
The weight of opinion, however, seems to relegate these problem-
atical bodies to the Invertebrata, and not improbably, as has been
urged for some of these forms, they represent the jaw-teeth of cer-
tain annelids.

Silurian Fauna.—The fauna of the Silurian period marks a
decided advance upon its predecessor. The chain of organisms
which, with the exception of the somewhat doubtful conodonts,
was hitherto constituted exclusively by the members of the inver-
tebrate series—sponges, echinoderms, mollusks, articulates—exhib-
its here for the first time indisputable representatives of the more
highly organised group of the vertebrates; but not until the Upper
Silurian deposits are reached. We here meet with the remains of
two distinct orders of fishes, the sharks or dog-fishes (Elasmo-
branchii), as represented by Onchus and Thelodus, and the bucklered
Ganoidei—Pteraspis—the former still very abundant in the modern
seas; the latter, which include, among other forms, the sturgeon
and alligator-gar, probably nearly verging on extinction.* In both
these orders the osseous framework or skeleton is frequently in a
more or less imperfect condition—complete ossification being the
exception rather than the rule—and hence, in so far, these primi-
tive vertebrates exemplify a low grade of organisation compared
with those—like the bony fishes, and most of the animals above
them—in which the vertebral column is completely ossified, or
reaches its furthest development. Nor are other characters want-
ing proving inferiority of organisation. We have here, therefore,
another illustration of the very important fact—a fact sustaining
the inference of the progressive evolution of higher from lower

* The oldest fishes were, until recently, supposed to belong to the British
Ludlow beds; but the discovery, by Professor Claypole, of ichthyic fragments
in deposits below the “* Water-Lime”’ of Pennsylvania would seem to remove
them stil! farther back in the geological scale.

SILURIAN FAUNA. 143

forms of life—that the representatives of each class of animals were
first ushered in in their simplest or most embryonic forms, and that
not until these had attained a considerable development was there a
noticeable appearance of the more highly constituted forms. It is
a significant (even if not a very remarkable) fact that, prior to the
first introduction of this lowest class of the Vertebrata, all the
larger divisions of the Invertebrata, as now recognised by natu-
ralists, had already come into existence. Of these, the diversity
of form in the Silurian deposits, no less than the numerical de-
velopment, is very great, and equally so in almost all the classes
represented.

The most marked feature of the Silurian invertebrate fauna, as
contrasted with the Cambrian, is furnished by the corals, which,
barring a few forms doubtfully belonging to the Cambrian of
Sweden, have here their earliest representatives. These primitive
types of the Actinozoa, as well as nearly all others of the Paleozoic
series of deposits, have generally been recognised by naturalists to
constitute two well-defined groups, the Tabulata (Favosites, Haly-
sites, Heliolites, Alveolites, &c.) and the Rugosa, or cup-corals (Cy-
athophyllum, Streptelasma, Omphyma, Zaphrentis, &c.), in both of
which the calyces are divided up into superimposed chambers by
transverse plates or tabule—the former with very rudimentary septa,
the latter with the septa well developed, and the outer calicular
wall greatly thickened. In the majority of these cup-corals the
septa are disposed in multiples of four (Tetracoralla), whereas in
nearly all recent Madreporaria this disposition is effected in multi-
ples of six (Hexacoralla). Our recently acquired knowledge of the
deep-sea fauna, and a more intimate acquaintance with the anatomy
of some of the more aberrant species of coral, tend to show that
the supposed sharp delimitation of ‘the Paleozoic actinozoan fauna
does not in reality exist. The tabulate corals, for example, whose
final extinction with the Paleozoic era has generally been insisted
upon as one of the most decisive of geological landmarks, would
seem to hold a number of forms more or less closely related to
types living in the modern seas, which in themselves combine most
diverse features in their organisation. The genera Halysites and
Syringopora appear to be not distantly removed from the recent
organ-pipe (Tubipora); Favosites is placed among the Poritide;
and Heliolites not impossibly represents an ancestral form of the

144 GEOLOGICAL DISTRIBUTION.

group to which the modern Heliopora, recently claimed to be an
alcyonarian, also belongs.* The rugose-corals, apart from the very
limited number of forms which occur fossil in deposits newer than
the Paleozoic—? Holocystis (Cretaceous), Conosonilia (Tertiary)—
have apparently two living representative types in Guynia and Hap-
lophyllia. On the other hand, the modern star-corals, if we exclude
from this group the Favositide, have but a feeble development in
the earlier deposits, although several recent families are represented
(Poritide, Eupsammide, Astreide). Of the genera belonging to
this group, Protarza, Stylareea, Prisciturben, and Calostylis date
back to the Silurian period.

The remarkable development of corals in the Silurian seas makes
it not a little difficult to account for the total, or almost total, ab-
sence of their remains in deposits of the preceding Cambrian age.
It is scarcely credible that the animals of this class should not have
already then existed; but if so, what has become of them? In ex-
planation of this anomaly some geologists have urged that the
strata of Cambrian age which contain recognisable fossils are all of
a deep-sea origin, and that in the shallow and littoral deposits,
where we might be expected to look for the traces of the organisms
in question, organic remains have been completely obliterated
through rock-metamorphism of one kind or another. The evi-
dence supporting this hypothesis is, however, far from satisfac-
tory, and the problem must be considered as one still awaiting
solution.

The graptolites, a group of organisms whose earliest remains
are found in the transition rocks which unite the Cambrian and
Silurian formations, and whose organisation appears to be most
nearly reflected in that of the recent sertularians or sea-firs of the
class Hydrozoa, constitute an important element in the Silurian

* The reference of Favosites to the Poritidee, it must be confessed, is based
upon rather slender evidence, and perhaps seareely less so the placing of
Heliolites among the Alcyonaria. Hdérnes (‘‘ Elemente der Paleontologie,”’
1884) justly emphasises the artificiality of a classification in which the number
and disposition of the septa and tentacles are made the basis for a division
into primary groups, and in which other equally important characters are com-
pletely lost sight of. The relationship existing between past and recent forms,
taken in conjunction with the general homogeneousness of character exhibited
by the Tabulata, would seem to imply that the classification of the recent
Actinozoa requires serious emendation.

SILURIAN FAUNA. 145

fauna, becoming practically extinct with the close of that period.*
It is a noteworthy circumstance in connection with the history of
this family that the more complicated or double-stemmed forms, such
as Diplograptus, Didymograptus, Phyllograptus, and Dichograptus,
preceded, in the order of appearance, the simple-stemmed forms, like
Monograptus and Rastrites, proving, contrary to what might have
been naturally supposed, that the latter were not the ancestral types
of the family. On any evolutionary hypothesis the simpler forms
appear to have been brought about as the result of degeneration.
In modern type hydrozoans the Silurian, as all other Paleozoic, de-
posits are very deficient, a circumstance, doubtless, due in con-
siderable part to the perishable nature of the organisms belonging
to this class. The impressions of jelly-fishes have, however, been
indicated in both the Cambrian and Silurian rocks of Sweden.
Stromatopora, a very broadly distributed genus, whose affinities
are now generally conceded to be with the Milleporida, passes into
the Devonian formation.

Of other Invertebrata, such as the echinoderms, mollusks, and
articulates, there is a vast profusion of forms, which, apart from
the mere matter of numbers, are in many respects sharply contrasted
with their predecessors of the Cambrian period. The brachiopod
mollusks, the predominant forms of which, as Spirifer, Atrypa,
Athyris, Strophomena, Rhynchonella, and Pentamerus, belong to
the group of the Brachiopoda articulata, are structurally consider-
ably in advance of the inarticulate genera Lingula, Lingulella,
Discina, and Obolus, which make up almost the whole of the
corresponding Cambrian fauna; the latter, as far as is known, con-
tains but a single precursor of the articulate division, Orthis. The
prodigious development of the Silurian Cephalopoda would of itself
be sufficient to distinguish the period from the period preceding.
While up to the present time only two species of this class, an
Orthoceras and a Cyrtoceras, are positively known from Cambrian
deposits, no less than eleven hundred species, referable to a very
considerable number of genera of Nautilide—Orthoceras, Cyrto-
ceras, Gyroceras, Endoceras, Gomphoceras, Phragmoccras, Lituites,
Nautilus, &c.—have been described from the Silurian basin of Bohe-
mia alone. The total number of species of this period may be

* The somewhat problematical Dictyonema passes into the Devonian:
Triplograptus, if a true graptolite, is Devonian.

146 GEOLOGICAL DISTRIBUTION.

estimated at between two and three thousand. The genus Gonia-
tites, which effects a partial transition between the Nautilide and
the Mesozoic ammonites, appears for the first time in the later
Silurian deposits.

It is a surprising fact, considering the remarkable development
of the Cambrian trilobitic fauna, that not only are none of the
earlier species represented in the Silurian deposits, but that by far
the greater number of generic types, and more particularly those
which by a special individual or specific development are rendered
most important, as Paradoxides, Dikelocephalus, Olenus, Sao, and
Conocephalus, should be also wanting. Only seven out of some
twenty-seven genera of the primordial zone connect the formations of
the two periods. The Silurian Trilobita comprise probably in the
neighbourhood of fifteen hundred species, referable to some fifty or
more genera; yet of this vast number there are barely a half-dozen
species which transgress the boundaries of the formation, passing
into the Devonian. Among the more abundantly represented gen-
era are Phacops, Dalmania, Calymene, Asaphus, Trinucleus, Aci-
daspis, end Cheirurus.

Viewed irrespective of numerical development, the most signi-
ficant feature connected with the Silurian invertebrate fauna is the
introduction of the earliest ‘‘air-breathers.” Until recently these
were supposed to belong to the period following, the Devonian, but
the discovery of a true scorpioid (Paleophoneus) in the Upper Silu-
rian deposits of both Sweden and Scotland, and of an apparent
orthopteroid (Paleoblattina) in the nearly equivalent deposits of
Calvados, France, proves conclusively that a very considerable
differentiation among the air-breathing arthropods had already
taken place, and points to a period very much more ancient for the
first origination of the group.*

Devonian Faun2,—The primitive air-breathing arthropod fauna
just referred to finds a somewhat larger extension in the rocks of
Devonian age, where fragments belonging to some five or six spe-
cies of insect, possibly representing as many genera—Platephemera,
Gerephemera, Lithentomum, Homothetis, Xenoneura, Discrytus—
have been discovered. These appear to belong to the modern

* The seorpion described by Professor Whitfield (‘' Science,” July 31,

1885) from the Upper Silurian rocks of New York may, as suggested by Mr.
Poklman (‘ Science,’’ September 4, 1885), prove to be a young eurypteroid.

DEVONIAN FAUNA. 147

group of the netted-veins (Pseudoneuroptera and Neuroptera),
although by some authors they, as well as all other Paleozoic
insects, are considered to represent a distinct, and now wholly
extinct, type of Insecta, the Paleodictyoptera. In whichever way
their relationship be viewed, there can be little doubt that they
represent very nearly the lowest structural type of their class. It
is a very remarkable fact that the wing venation of these primi-
tive insect forms is practically identical with that which charac-
terises the modern insects belonging to the same group or order;
the vast lapse of ages between the Devonian period and our own
day appears to have effected no essential modification of structure
in this particular direction. Besides these neuropterous forms,
certain wing fragments have been referred to the members of the
higher order Orthoptera, to which the modern grasshopper and
cockroach belong. But there seems to be considerable doubt as to
the claims of the so-called Devonian cockroach,* and it would,
perhaps, be as well to consider its position as still a matter of un-
certainty. The marked differentiation exhibited by the Devonian
insects indicates that they were far more numerous than would
appear from the paucity of their remains, and the inference drawn
as to their great antiquity has been confirmed by the discovery of
the Upper Silurian form already referred to. - Coincidently with
the appearance of these early inhabitants of the land surface, we
remark the first considerable development of a land vegetation,
whose earliest traces are to be met with in the Silurian period.
With but very few exceptions (certain forms, as Prototaxites,
Ormoxylon and Dadoxylon, considered by some authorities to.
represent true conifers, the first of their kind) all the Devonian
plants belong to the lower or non-flowering division, the Crypto-
gamia, comprising a multitude of ferns, tree-ferns, giant representa-
tives, like Sigillaria and Lepidodendron, of the modern club-mosses
(Lycopodiacez), and scarcely less gigantic forms (Calamites, Cal-
amodendron, with Annularia, Asterophyllites, Sphenophyllum) be-
longing to the group of the horse-tails (Equisetacee).

Of Invertebrata other than insects the Devonian fauna is very
rich in forms; but these show a marked similarity to those of the

* Referred by Ilagen to the Neuroptera. The same authority considers
the age of the rock formation in which the other insect remains have been
found as more likely Carbonifcrous than Devonian.

148 GEOLOGICAL DISTRIBUTION.

preceding period. Approximately the same types are represented,
and while in the case of certain families a diminution in the number
and variety of their representatives is noticeable, in others there is
a corresponding increase. The corals, echinoderms, cephalopods,
and brachiopods have approximately the same value as in the Silu-
rian period, and, indeed, several of the specific forms that are to be
met with in the one formation are also seen in the other. Among
the Devonian brachiopods we have the first appearance of the genus
Terebratula, a form which has continued to flourish, although in
constantly diminishing numbers, from that period down to the
present time. With it are associated a number of other genera—
Strophalosia, Productus, Uncites—which likewise appear here for the
first time. The gasteropods are all of the holostomatous or round-
mouthed type— Pleurotomaria, Murchisonia, Euomphalus, Loxo-
nema, Holopea, Platyceras, &c.—while the lamellibranchs, which
show a marked increase, both in numbers and variety of form, over
their Silurian predecessors, belong, es far as it has been possible to
ascertain, exclusively to the Integropalliata, or such as are devoid
of a sinual inflection to the pallial line. The families represented
are either Heteromyaria (Aviculide, Mytilide) or Dimyaria (Nucu-
lid, Arcade, Astartide, Cardiid), no true Monomyarian being as
yet known. We meet here with the first pulmonate, Strophites,
a member of the modern family of snails (Helicide), and likewise
with what appears to be the earliest unequivocal fresh-water inver-
tebrate, a mussel of the genus Anodonta, or one very closely allied
to it. It is here, therefore, that we have the earliest undoubted
traces of a fresh-water formation.

The trilobites among Crustacea manifest a very rapid decline,
and, indeed, in some regions they appear to have completely died
out with the close of this period. The giant eurypterids—Euryp-
terus, Pterygotus, Slimonia—the most formidable of all known
living and extinct crustaceans—which first appeared in the Upper
Silurian formation, linger on into the succeeding Carbonifercus
period, when they forever disappear. The Devonian deposits, as
has already been stated, contain the earliest remains of the highest
order of crustaceans, the Decapoda, or ten-footers, which comprise
the modern lobster and crab; the form in question (Palesopalamon)
belongs to the macrurous, or long-tailed division, and is allied to
the shrimps.

DEVONIAN FAUNA. 149

The vertebrate life of this period exhibits a remarkable develop-
ment as compared with that of the period preceding. But, as in
the latter, all the remains belong to the class of fishes, and indeed
principally, or one might say almost exclusively, to the same two
orders, the elasmobranchs and ganoids. No animal of a grade
higher than fishes had as yet appeared upon the scene, or, if possi-
bly it had, no traces of it have thus far been discovered to indicate
its existence there. To such an extent was the fish-fauna developed
that the term ‘age of fishes” has not inappropriately been applied
by paleontologists to designate this epoch of geological time. The
preponderating types are the ganoids, which appear not only in
forms that may be considered more or less remotely related to the
type of the modern sturgeon (Macropetalichthys), or to the fringe-
finned Polypteri of Africa (Holoptychius, Glyptolepis, Dipterus,
Osteolepis), and the American alligator-gars (Chirolepis), but in
such as have no representatives in any of the succeeding formations.
These are the so-called ‘‘bucklered ganoids,” which, in addition to
the enamelled plates characteristic of this group of fishes, had the
head and the anterior portion of the body encased in bony plates,
more or less firmly united to each other, and serving as a protective
armour. To this group, among others, belong Pteraspis, Cepha-
laspis, Pterichthys, and Coccosteus, forms which had their forerun-
ners already in the Upper Silurian deposits. Generally placed among
the ganoids, and closely related to Coccosteus, are the giant Dinich-
thys and Titanichthys, which appear to have attained a length
of from twenty to thirty feet, and whose dental apparatus closely
approximates that of the modern Lepidosiren, one of the lung-fishes
(Dipnoi), a group of animals which effect a transition between the
true fishes and the amphibians. If this relationship with Lepido-
siren be absolutely established, as is claimed to be the case by many
of the more prominent anatomists, then it is certainly significant that
the advent of the Amphibia (the class of animals immediately above
the fishes), in the succeeding Carboniferous period, is preceded by
just that growp which, in accordance with the principles and work-
ings of evolution, we should expect to find interposed—the group
which, on the one hand, combines some of the characters of the
Amphibia, and, on the other, those of the ichthyic fishes. But,
whatever the exact relationship of Dinichthys may be, there can be
little question as to its representing a dipnoan type, or at least a

150 GEOLOGICAL DISTRIBUTION.

transition form between the true ganoids and the lung-fishes. A
imilar position is occupied by some of the other crossopterygian
fishes of the period, as D:pterus.

Uarboniiercus Fauwia.—The life of the Carboniferous period is
marked by two important features: 1. The introduction for the first
time of vertebrate animal forms higher in the scale of organisation
than the fishes, 2. e., the amphibians; and 2. The great develop-
ment of strictly air-breathing or terrestrial animals. Of these last
we have at least four distinct types indicated—the Gasteropoda,
Insecta, Arachnida, and Myriapoda. Of the first, which have a
solitary forerunner in the Devonian formation, we are acquainted
with a comparatively limited number of forms (Pupa, Anthraco-
pupa, Dawsonella, Zonites), all of them more or less closely related
to forms still living at the present day. The insects comprise not
only members of the low order of netted-veins, which are the only
forms known to be represented in the Devonian deposits, but those
of the more highly organised Orthoptera, and not improbably also
Coleoptera (beetles), although most of the remains referred to the
latter order are now positively known not to belong there. The
Orthoptera comprise, among other forms, some sixty or more spe-
cies of primitive cockroach, the Paleoblattariz#, which may be con-
sidered to represent the ancestral type of the modern social pest
(Blatta), whose earliest appearance dates from the Triassic period.
To the same order belong the giant walking-sticks recently brought
to light from the coal-measures of France, the Titanophasma Fayol-
lei, which measure in length (in one specimen) upwards of twelve
inches, and are, therefore, by linear measure, very nearly the largest
of recent as well as fossil insects.

This extraordinary development of a form, which may be taken
to represent the extreme term of specialisation in an insect, in a
period so early as the Carboniferous, is certainly not a little re-
markable, and argues very strongly for the great antiquity beyond
its own period of the origin of this class of animals. It is also not
a little surprising that no representatives of the family of walking-
sticks (Phasmida), other than those found in the Carboniferous
deposits of France—Titanophasma and Protophasma—heve as yet
been found in a fossil condition, except such as may have been
preserved in amber. Of the Neuroptera, the Haplophlebium Bar-
nesii, from Nova Scotia, attained an expanse of wing of seven

CARBONIFEROUS FAUNA. 151

inches, nearly equal to the expanse of the largest of the living
dragon-flies, to which it appears to have been related. The Car-
boniferous Arachnida comprise representatives of true spiders (Pro-
tolycosa, Anthracomartus), scorpions (Eoscorpius, Cyclophthalmus),
and pseudo-scorpions (Microlabis). The scorpions appear to have
attained a degree of specialisation very little below that of their
modern representatives; but the true arachnids have all, or nearly
all, segmented abdomens, and may be considered to mark a transi-
tion between the arthrogastric and anarthrogastric forms. The
Myriapoda, which have a solitary forerunner in the Devonian rocks
of Scotland (Forfarshire), are represented by both the cheilognath-
ous and cheilopodous types, although on account of certain structu-
ral peculiarities the greater number of these earlier forms (Eupho-
beria, Xylobius, Trichiulus) have been constituted into a special
order, the Archipolypoda.

Of the remaining invertebrate fauna of the Carboniferous period
little need be said. The various groups of the tabulate and rugose
corals (Lithostrotion, Syringopora, Cyathophyllum, Amplexus, Za-
phrentis), the brachiopods, pteropods, lamellibranchs, gasteropods,
and cephalopods, among the mollusks, and the crinoids and blas-
toids (Actinocrinus, Platycrinus, Cyathocrinus, Dorycrinus, Batto-
crinus, Pentremites, Granatocrinus) of the Echinodermata, have,
as in the Devonian formation, abuadant representatives; but they
belong in considerable part to genera which now appear for the
first time, or to such as had but a feeble development hereto-
fore. The widely distributed group of trilobites, which, as has al-
ready been seen, played such an important part in the faunas,
of the Cambrian and Silurian periods, has here barely four gen-
eric representatives, Phillipsia, Proetus, Griffithides, and Bra-
chymetopus, whose species occur in the main part in the deposits
situated below the true coal.* With these forms the trilobites
disappear forever from the scene. While the deposits of the pre-
ceding Silurian and Devonian formations have shown a fair repre-
sentation of at least two of the primary groups of the Echinoder-
mata, the Asteroidea and Crinoidea, especially of the latter, it is
not until the present period that the urchins themselves (Echinoidea)
acquire any significance (Archeocidaris, Palechinus, Melonites);

* Professor Claypole has latterly announced the discovery of Dalmania in
the ‘‘ Waverly group”? (Lower Carboniferous) of Ohio.

152 GEOLOGICAL DISTRIBUTION.

and here, also, for the first time, if we except the Laurentian rocks,
with the hypothetical Eozoon, do the Foraminifera appear to enter
largely as rock constituents. The genus Fusulina is developed to
an extraordinary extent, and its distribution appears to be but little,
if at all, less universal than that of the genera Nummulites and
Orbitoides of the Eocene period. A solitary forerunner of the
Nummulites has been discovered in the Carboniferous rocks of
Belgium.

In the remarkable development of the elasmobranch (shark)
type of fishes, and in the absence of the bucklered ganoids, the
Carboniferous ichthyic fauna is sharply defined from that of the
Devonian. With the exception of a considerable number of fin-
spines or ichthyodorulites, referred to such genera as Ctenacanthus,
Gyracanthus, Oracanthus, &c., whose position is still very doubt-
ful, and which may in part belong to the order of ganoids, all the
remains of the former appear to have been more or less nearly
related to the modern Port Jackson sharks. These remains are in
the main in the form of teeth—Psammodus, Helodus, Orodus,
Chomatodus, Petalodus, Cochliodus—whose (somewhat distant)
resemblance to the pavement teeth of the cestracionts has led to
their reference to members of that group ; not impossibly, how-
ever, they represent a very distinct type.* The ganoids comprise,
in addition to polypteroid forms—Ceelacanthus, Rhizodus, Megal-
ichthys—representatives of the rhomb-plated Lepidosteidei, which
include the American alligator-gar. The most widely distributed
and most abundantly represented genera are Palzoniscus and Am-
blypterus, the former of which is also one of the most abundant —
fishes of the succeeding Permian period.

The only vertebrates other than fishes which appear in the Car-
boniferous period, and now appear for the first time, are the Am-
phibia, that group of animals whose members stand immediately
next above the fishes in the scale of organisation, and whose em-
bryonic forms are so clearly ichthyic as to have necessitated the
union of the two classes into the one comprehensive division of the
Ichthyopsida. It is not a little significant that the appearance of

* Mr. Garman has recently described a species of shark from the Japanese
seas, Chlamydosclachus anguineus, which appears to be generically most in-
timately related to the Carboniferous Didymodus, and which, accordingly, rep-
resents about the most ancient type among living vertebrates.

CARBONIFEROUS FAUNA. 153

these animals should have been foreshadowed in the Devonian dip-
teroid ganoids, which, leading up to the lung-fishes on one side,
and not impossibly directly to the amphibians on the other, effect
a transition to the higher class from the side of the fishes. This
succession of higher upon lower types is not a matter of accident,
but a direct outcome of the inevitable laws of evolution. Through
the application of no other law would the numerous accidental or
coincidental occurrences of direct succession, which present them-
selves throughout the entire geological series, receive an intelligent
explanation. All the Carboniferous amphibians belong to the ex-
tinct order of the Labyrinthodontia (Stegocephala), salamandroids
of both minute and gigantic frame, whose members were distin-
guished by the possession of a dermal (cephalo-dorsal and ventral)
armour of sculptured plates, and in many cases by a peculiar laby-
rinthine infolding of the enamel of the teeth, a structure unknown
among modern amphibians, but which is in great part shared by
certain members of the ganoid fishes, as the modern alligator-gars
(Lepidosteus) and the genus Rhizodus (Carboniferous). Among
the genera are Anthracosaurus, Hylerpeton, Dendrerpeton, Batra-
chiderpeton, and the cecilian-like Dolichosoma and Ophiderpeton.
No other vertebrate higher in the scale of organisation than these
labyrinthodonts is as yet apparent, unless, possibly, the very doubt-
ful Eosaurus be proved to be a true reptile.

The flora of this period partakes essentially of the character of
that of the period preceding, the Devonian. We have here the
same ancient representatives of the modern club-mosses and horse-
tails, the Lepidodendra and their allies,* and the calamites, the
ferns—Neuropteris, Pecopteris, Alethopteris, Sphenopteris, Cyclop-
teris—giant tree-ferns, and forms that have been referred to the
group of the cycads, an order of plants to which the sago-palms
belong, and which appear to be not distantly removed from the
conifers. No positive indications of the existence of any true
flower-bearing herbaceous plants are yet manifest, and with their
absence the total absence of flower-frequenting or nectar-sucking

* The recent anatomical investigations of Renault and Saporta have led
these authorities to consider Sigillaria, at least in some of its recognised forms,
to be much more closely related to the gymnospermous phanerogams than to
the club-mosses; but Professor Williamson has pretty definitely shown that
such a relationship does not exist.

154 GEOLOGICAL DISTRIBUTION.

insects, the Lepidoptera and Hymenoptera, the two most highly
organised orders of insects, is noticeable. The only true trees, or
such as are made up principally of woody tissue, of the Carboni-
ferous deposits belonged to the coniferous series, the order of
plants which embraces the modern pine and its allies. These an-
cient evergreens were represented by several distinct genera—
Dadoxylon, Paleoxylon, Pinites—which, if the fossil fruit asso-
ciated with their remains, and known as Lepidostrobus, be justly
attributed to them, had their nearest allies among their modern
congeners in the berry-bearing yews. No deciduous leaf-bearing
trees, such as the oak, beech, or maple, which make up the great
mass of our forest growths, can be positively shown to have existed
in these early days.

Permian Fauna,—In the formations of the period succeeding
the Carboniferous, the Permian, a considerable advance in the
structural type is indicated by the animal remains. While the
predominant forms of life of the period preceding pass, although
in most cases with very diminished numbers, into the present one
—in fact, to such an extent as to have induced many geologists to
unite the formations of the two periods into a common whole—we
meet here with a class of animals whose representatives had not
hitherto been detected. These are the true reptiles, most of whose
members belonged to the order Theromorpha (Pelycosauria), rep-
tilian forms which in several important characters—the structure of
the pectoral and pelvic girdles, humerus, and tarsus—show strong
affinities to the lower orders of mammals, the Monotremata and
Edentata, of which, not impossibly, they may prove to be the early
progenitors. A further approximation to mammalian structure is
found in the character of the dentition, which in many forms ex-
hibits a distinct differentiation into incisor and canine teeth. The
deposits of the Southern and Western United States, especially of
the State of Texas, have yielded a wealth of species and genera
belonging to this order (Theropleura, Dimetrodon, Diadectes, Em-
pedocles, Clepsydrops), representative of several distinct families.
The modern type of lizards had their nearest analogues in the
monitor-like Proterosaurus (Germany, England), whose dentition,
however, was of the crocodilian type (thecodont). These early
reptiles, while exhibiting many points of structure indicative of
comparatively high specialisation, yet clearly proclaim a primitive

PERMIAN FAUNA. tos

type of crganisation in the rudimentary or embryonic condition of
the vertebral column, which is in most cases only partially ossified.

The Amphibia of the Permian period are by most authors placed
in the single group of the Labyrinthodontia, although in certain
structural departures from the normal type, as in the very rudi-
mentary condition of the vertebral column, and in the absence of
the peculiar labyrinthine infolding of the enamel of the teeth, some
of the forms may have to be separated from this order. Most of
the species were provided with a tail of greater or less length, and
the general resemblance to living amphibians appears to have been
mainly with the salamandoids, although in several points of struc-
ture they more closely approximate the tailless frogs and toads.
The relationship with the plated ganoids is well pronounced, and
not improbably some of these, as dipneusts, or double breathers,
-may have been their true ancestors (as well as of the lung-fishes
proper, Dipnoi). Among the more prominent genera are Branchio-
saurus, Melanerpeton, Urocordylus, Archegosaurus, Eryops, Palszo-
siren, and Ophiderpeton, the last two apparently apodal, and re-
calling the cecilians in outline. In Eryops megacephalus, the
largest of American amphibians, from the Permian of Texas, the
skull measures eighteen inches in length and twelve inches in
breadth.

The fish-fauna of this period partakes essentially of the char-
acter of the fauna of the period preceding, from which it has
borrowed most of its types. We have here, however, the first
unequivocal remains of the genus Ceratodus (Bohemia and Texas),
which represents the most ancient generic type of all existing
Vertebrata.

Regarding the invertebrate fauna of the period, it may be re-
marked that a deficiency in the number of forms is noticeable in
nearly all the localities where the Permian deposits are developed,
a circumstance due to the peculiar physical conditions under which
the deposits were formed, and the subsequent alteration, resulting
in the obliteration of the contained organic remains, to which, in
many places, the rock-masses were subjected. A very large pro-
portion of the known fossils are, as has already been intimated,
of clearly Carboniferous types, more especially in the case of the
Mollusca. The trilobites, so characteristic of the earlier deposits
of the Paleozoic era, are wholly wanting, not a single individual,

156 GEOLOGICAL DISTRIBUTION.

apparently, of this very numerous order having survived the Car-
boniferous period. Here, also, we have the almost final disappear-
ance of the two great groups of the rugose and tabulate corals,
which by their numbers so eminently characterise the limestone
deposits of the Paleozoic series, from the Silurian to its close. The
Permian flora is essentially that of the Carboniferous period, and
requires no special consideration.

Paleozoic Faunas.—Briefly reviewing the more salient features
of the Paleozoic faunas, we find, as far as the invertebrate series is
concerned, that with few exceptions all of its recognised classes
have their representatives, or, at least, there are representatives of
nearly all those classes whose members could reasonably be expected
to have been preserved in a fossil state. Thus, of the Protozoa we
have the Foraminifera and Spongida; of the Coelenterata, the Acti-
nozoa and Hydrozoa; of the Echinodermata, the Echinoidea, Aste- ~
roidea, Ophiuroidea, Crinoidea, Cystidea, and Blastoidea ; of the
Mollusca (and Molluscoida), the Polyzoa, Brachiopoda, Acephala,
Pteropoda, Gasteropoda, and Cephalopoda; and of the Articulata,
the Crustacea, Arachnida, Myriapoda, and Insecta. Of the classes
here enumeratedthere are wanting in the Cambrian the Actinozoa,*
and possibly also the Hydrozoa; the Echinoidea, Blastoidea, and
Ophiuroidea, among the echinoderms ; and the Arachnida, Myria-
poda, and Insecta, among the articulates. In the Silurian the
number of missing classes is reduced by six, since we have here
representatives of both corals and hydroids, blastoids and brittle-
tars, insects and arachnids; but the last two are represented almost
by single individuals. In the Devonian the number is further re-
duced by one, the class of the Myriapoda, likewise (as is also the
case with the insects) represented in almost solitary individuals;
only with the Carboniferous period do all the classes acquire for
the first time any marked development. We thus cannot fail
to remark the progressive evolution of new forms correlatively
with the advance of time. Of the vertebrate series the Paleozoic
deposits contain the remains of only three of the five recognised
classes, the fishes, amphibians, and reptiles, which appear serially
in the order of their progressive organisation, the lowest, or fishes,
in the Silurian (or, if the conodonts be fishes, in the Cambrian), the
amphibians in the Carboniferous, and the highest, or true reptiles,

* Some forms have been doubtfully referred to this period in Scandinavia.

TRIASSIC FAUNA. 157

in the Permian. These ancient deposits have as yet yielded no
traces of either birds or mammals.

Triassic Fauna.—lIn the first of the Mesozoic series of forma-
tions, the Triassic, we enter, as it were, upon an entirely new phase
of organic development. Many of the mere characteristic groups
of organisms of the preceding era have now either completely dis-
appeared, or only survived in such diminished numbers as to con-
stitute but a very insignificant element in the new fauna. Thus, of
the class Brachiopoda but comparatively few of the older generic
types are represented; and the same may be said ofthe other classes
of mollusks, and more especially of the Cephalopoda. Of all the
various forms of Paleozoic tetrabranchiates there are barely more
than a half-dozen surviving types, and of these one, Orthoceras, itself
becomes extinct in this period. But, in the place of these ancient
types, we have others of the same class which are no less conspicu-
ous for their numbers than for the complexity of form which they
subsequently attain, and some of which exhibit a marked advance
upon their predecessors in the scale of organisation. The ammo-
nites, whose advent appears to have been foreshadowed in the
goniatite and the Devonian Clymenia, now for the first time
acquire any importance, and, indeed, if we except certain forms
from the Carboniferous deposits of India and Texas—Arcestes,
Xenodiscus, Sageceras, Medlicottia—now for the first time appear
altogether. The numerous species which in some districts, more
especially in the region of the Alps, crowd the deposits of this age,
belong in principal part to the families Arcestidee and Pinacocera-
tidx, as representatives of the leiostracous, or smooth-shelled divi-
sion, and the Tropitide, Ceratitide, and Clydonitide (with the
somewhat aberrant genera Cochloceras, Rhabdoceras, Choristoceras,
and Clydonites), of the Trachyostraca, or forms with strongly sculp-
tured shells.

In these deposits, also, we meet in the Belemnitide with the first
unequivocal traces of the dibranchiate or two-gilled, cephalopods,
which, if we except the Nautilus, alone of this class of mollusks
inhabit the seas of the present day.* The rugose and tabulate

* The view entertained by several eminent paleontologists, that the am-
monites themselves represent dibranchiate forms, requires further support
before it can be fully accepted. The evidence at the present time appears to
be fully as much, if not more, opposed to this notion as it is in favor of it.

158 GEOLOGICAL DISTRIBUTION.

—s

corals have been succeeded by the modern type of the star-corals,
Zozutharia perforata and aporosa (Montlivaltia, Thecosmilia, Isas-
trea, Thamnastrea, &c.), whose fregmentary remains build up giant
reeis (Alps); and, similarly, the more distinctive ancient group of
the Echincdermata, the crinoids, whose most characteristic repre-
sentatives at this period are Encrinus and Pentacrinus, find their
successors largely in the more modern Echinoidea, or trie urchins
(Cidaris, Hemicidaris, Hypodiadema).

It is, however, in the vertebrate fauna that we find the most
prominent feature separating the life of this period from that of any
of the periods preceding. Not only do we meet here with the re-
mains of fishes, amphivians, and reptiles, but with those of mam-
mals, and not improbably also with the impressions or tracks of
birds. Granting these last, which are, however, a little uncertain,
it may be assumed that all the classes of the animal kingdom, as
now recognised by naturalists, had their representatives. The fishes
are still principally referable to the predominant type of the periods
preceding, the ganoids, which also in a measure retain the embry-
onic heterocercal tail, although a tendency towards homocercality is
observable in some of the genera, as in Semionotus. The more
numerously represented forms—Ischypterus, Catopterus, Semionotus
—tbelong to the group typified in the American gar-fishes, and may
be looked upon as the direct descendants of the Carboniferous
and Permian Paleonisci. The lung-fishes find an abundant repre-
sentation in the teeth of Ceratodus, which, as has already been
seen, dates from the Permian, and possibly from a still older
period. This animal furnishes us with one of those rare instances
where a genus of living vertebrates has been founded upon the
fossil remains.

The amphibians of the Triassic period show but little advance
over the type of their predecessors, all the forms still belong-
ing to the single order Labyrinthodontia, some of whose members
attained to prodigious dimensions (Mastodonsaurus, Labyrintho-
don). To this group are probably referable the singular hand-
sheped impressions of the animal known as Cheirotherium, or
‘‘hand-beast,” originally supposed to have been an animal of the
frog-type, but now assumed to have been a salamandroid, or animal
allied to the newts, and, like them, provided with a tail, although
possessing in the structure of the skull certain features belonging

TRIASSIC FAUNA. 159

to the tailless amphibians—frogs and toads. The true reptiles ex-
hibit a remarkable variety of form, and, as in the succeeding Juras-
sic and Cretaceous periods, constitute the most marked feature of
the faunal remains that have been left to us. Hence, by some
geologists the collective era of these three periods—the Triassic,
Jurassic, and Cretaceous—or what is generally known as the Meso-
zoic, has been designated the “cra” or “age of reptiles.” The
modern lizards and crocodiles had both their ancient representa-
tives, the former as indicated by the genera Telerpeton, Hypero-
dapedon, and Rhynchosaurus, and the latter by Stagonolepis, Belo-
don, and Parasuchus. But besides these there flourished a multi-
tude of reptiles belonging to several distinct and very widely
removed orders, which have left, to our knowledge, no traces
whatever of their existence in the present seas. Such are the South
African Anomodontia, some of whose members, as Oudenodon,
were totally destitute of teeth, and had their beaks encased in
horn, after the fashion of the modern turtles (of which they may
have been in part the progenitors); while others, 2s Dicynodon,
possessed the horny mandibular apparatus of the former, but were
provided, in addition, with a pair of huge and powerful teeth in
the upper jaw;* the Theriodontia (as represented by the South
African Galesaurus), reptiles whose dentition partook of the char-
acter of that of the ordinary Carnivora, and whose earliest types had
already appeared in the deposits cf the Permian period; and the
Plesiosauria, a group of essentially sea-inhabiting reptiles, which
acquired a very considerable development in the Jurassic seas, and
whose best known exponent is the Plesiosaurus. In the animals of
this order the extremities of the limbs, both anterior and posterior,
were encased in integument, and thus converted into flippers, very
much like those of the whale, and admirably adapted for propul-
sion through the water. The most characteristic genera of this
period were Nothosaurus and Simosaurus. In Placodus the dental
armature consisted in principal part of flattened plates, resembling
the teeth of the pyenodont fishes, with which animals these reptiles
were first confounded.

* Professor Judd has quite recently (‘‘ Nature,’ October 15, 1885), an-
nounced the discovery of dicynodont remains in the Elgin Trias of Scotland;

the group of animals had hitherto been known only from Africa, India and
the Ural Mountains.

160 GEOLOGICAL DISTRIBUTION.

The most remarkable of all the Triassic reptiles are the Dino-
sauria, a group of the greatest importance when viewed from a tele-
ological standpoint by reason of the many structural characters
which separate them from the typical reptiles, and approximate
them to birds. These avian characters are indicated principally in
the structure of the powerful pelvic girdle and hind limbs, which
depart very broadly from the normal type of reptilian structure.
Thus, the pubic bones, in many cases, instead of projecting for-
wards as in other reptiles, are directed backwards, more nearly
parallel with the ischium, both bones therefore taking a position
directed towards the posterior portion of the body, a feature char-
acteristic of birds. In the hind limb, again, the ornithic char-
acters are seen in the great cnemial ridge which is developed on
the tibia, the gradual diminution of the fibula towards the distal
extremity, the structure of the astragalus, and in the disposition of
the digits, three or more, and their accompanying phalanges. The
inner and outer digits are shorter than the rest, or quite rudi-
mentary, and the third toe, as in birds in general, is the longest.
There are good grounds for concluding that the bones of the limbs,
and, doubtless, if this was the case, of some of the other portions
of the trunk, were permeated with air-passages, as in birds. The
structure of the fore limbs is still only imperfectly understood,
but there is no doubt that in many cases they were but very
feebly developed, being very much shorter than the hind limbs,
and that progression was, either habitually, or at least at times,
effected by means of the posterior appendages alone. The remains
of these earliest dinosaurs are indicated both by the actual parts
pertaining to the skeleton (Zanclodon, Thecodontosaurus, Amphi-
saurus, Clepsysaurus, Bathygnathus), and by the foot-prints, many
of them three-toed, that have been left implanted in the rock-
masses. Some of these, which measure fully a foot, or even con-
siderably more, in length, were originally supposed to represent the
imprints made by the feet of giant birds, a suspicion strengthened
by the serial arrangement in twos in which the tracks are disposed ;
but now that the structure of the dinosaurs has been more accu-
rately determined, and their ornithic characters and mode of pro-
gression recognised, there can be little doubt that they represent
the imprints of the reptiles belonging to this order. This view is
further strengthened by the circumstance that no actual remains of

JURASSIC FAUNA. 161

birds have as yet been discovered in deposits of Triassic age.* But
it is not impossible, or even improbable, that some of the smaller
foot-prints that are scattered about the larger ones, and which in
some instances are disposed in a single series one in advance of the
other, indicating a method of progression adopted by certain wad-
ing birds, may actually be of an ornithic nature. However this
may be, it is certainly a significant fact bearing upon the doctrine
of evolution, that no unequivocal traces of birds have thus far been
discovered in deposits antedating those which contain the remains
of reptiles, which in their several characters most approximate the
birds, and in reality effect a transition to them. The progressive
evolution of advanced or most specialised types is here clearly
indicated.

The Mammalia, the highest class of vertebrates, appear for the
first time in the deposits of this age. They are indicated by the
tecth and fragmeuts of jaws pertaining to two or three genera,
Dromatherium, Microlestes, and Hypsiprymnopsis, forms, as nearly
as can be determined, belonging to the low type of the Marsupialia,
and, probably, more or less closely allied to the modern banded
ant-eater (Myrmecobius) end kangaroo-rats (Hypsiprymnus) of Aus-
tralia.

Jurassic Feuna,—The life-history of the Jurassic period, while
combining certain prominent features not hitherto recognised, pre-
sents to us primarily an expansion of those characters with which
we have just become acquainted. The remarkable group of the
dinosaurian reptiles, whose development in the Triassic period had
but barely passed beyond its own beginnings, acquires here re-
newed importance, apart from the mere matter of numbers, from the
circumstance of the gigantic and diverse forms which it includes.
Four distinct types of this order are recognised, all of which had
representatives in the Jurassic period: 1. The Sauropoda, lizard-
footed vegetable-eaters, in which the anterior and posterior pairs
of limbs were of nearly equal length, and whose progression was
effected on all fours. Among the more important genera of this
period belonging to the group are Atlantosaurus, Brontosaurus,
Morosaurus, and Cetiosaurus, the first, from the deposits of the

* Since the above was written announcement has been made of the dis-

covery of the skeletal remains of a track-making dinosaur of the Connecticut
Valley. Trans., New York Ac. Sciences, Oct. 26, 1885.

162 GEOLOGICAL DISTRIBUTION.

Rocky Mountains, measuring from eighty to one hundred feet in
length—the largest land animal with which we are acquainted.
2. The Stegosauria (Stegosaurus, Scelidosaurus), armoured vegeta-
ble-feeding dinosaurs, some of them of gigantic frame, whese pro-
gression, owing to the feeble development of the anterior pzir of
limbs, appears to have been in great part effected by means of the
hinder extremities alone. In Scelidosaurus Harrisoni, from the
Lias of Dorsetshire, the hind foot measured three feet and a half in
length. 8. The Ornithopoda, bird-footed herbivores, with a very
unequal development of the anterior and posterior appendages,
the latter closely appreximating the structure found in birds.
There can be but little question as to the habitually erect posture
assumed by such forms as Camptonotus, Laosaurus, and Iguanodon.
Iguanodon Mantelli, a Cretaceous species, measured about thirty
feet in length from the tip of the nose to the extremity of the tail.
No member of this genus is known from the American deposits.
4, The Theropcda, carnivore forms, whose progression was largely
erect, and assisted in many cases, probably, by the greatly developed
tail acting as a fulcrum, in the manner of that organ among the
kangaroos. This type, which is almost alone represented in the
Triassic deposits, includes the most formidable members of the
order—Megalosaurus, Alloszurus, Dakosaurus, the former appar-
ently attaining a length of fiity feet. The genus Compsogna-
thus, represented by a single species (C. longipes) from the Upper
Oolite, possesses probably the greatest number of avian characters
of the entire order, and is considered to stand in the direct line of
the descent of birds.

Monsters parallel to those of the land-surface inhabited the
oceanic waters, such as the finned Plesiosaurus and Pliosaurus, and
the not distantly removed Ichthyosaurus and its American tooth-
less ally, Sauranodon. The geographical distribution of Ichthyo-
saurus is a very remarkable one. While apparently the genus is
completely wanting in the deposits of the New World, its range in
the Eastern Hemisphere embraced very nearly its whole north and
south extent, from Spitzbergen (Ichthyosaurus polaris, Triassic) to
Australia (I. australis, Cretaceous). Its greatest development ap-
pears to have been in the early part of this period (Lias). From
the discovery of fragmentary parts of young individuals within the
bodies of more fully developed ones, it has been conjectured that

JURASSIC FAUNA. 163

the animal was viviparous, a supposition in a measure strengthened
by the ill-adaptation of its structure to breeding on the land-surface.
Not impossibly, however, these animals may have been in the habit
of devouring their young, or the young of allied species, as it seems
many species of snake do at the present day.

In the Jurassic rocks we meet with the first traces of that ex-
traordinary group of reptiles, the Pterosauria, which, in the pos-
session of a tegumentary membrane stretched between the greatly
elongated outer digit of the anterior limbs and the bases of the
hinder extremities, resembling in many respects the flying-apparatus
of bats, were enabled to navigate the air in the manner of birds.
To these last, the pterodactyls, as the members of this order are
familiarly designated, were closely related in the general conforma-
tion of the skull, the pneumaticity of the bones, and the presence
of a well-developed keel to the sternum or breast-plate, a character
among recent animals found only in birds and bats. But while
possessing these and other avian features, the pterodactyls depart
in many important particulars from the bird type, and notably in
the presence of true teeth implanted in sockets, as in the Croco-
dilia, the structure of the manus, the absence of a feathery integu-
ment—the animal having been apparently provided with a naked
skin—and the possession of a tail composed of distinct vertebree.*
Despite these important differences, however, it may, perhaps, be
deemed doubtful whether the animals in question have not as
much right to be considered birds as reptiles, the more so as the
one great feature separating them from modern birds, the pres-
ence of alveolar teeth, has recently been shown to be character-
istic of some, if not of most, of the ancient birds. While, there-
fore, it may not be possible to decide upon the exact position oc-
cupied by these singular organisms, there can be but little doubt
that they, or possibly some closely-allied predecessors with which
we are not as yet acquainted, represent the primitive stock whence
the type of the modern flying or carinate bird has been evolved.
The birds would then have a double line of ancestry, the one here
indicated, and another, culminating in the struthious or non-carinate

* Professor Marsh has shown that at least in some forms of pterodactyls
(Rhamphorhynchus) the extremity of the tail was provided with a tegu-
mentary expansion, or vertical rudder, by means of which the animal doubt-
less guided its flight.

164 GEOLOGICAL DISTRIBUTION.

birds, having its origin in the dinosaurian reptiles, and in a form
possibly not distantly removed from the Jurassic Compsognathus.
The more important Jurassic genera of Pterosauria are Pterodacty-
lus, Rhamphorhynchus, and Dimorphodon, which differ from each
other mainly in the character of the dentition and in the relative
development of the tail.

The deposits of this age have yielded, in addition to the reptilian
forms mentioned, the remains of true lizards, crocodiles, and turtles.
The first are but sparingly represented, and in the main, or wholly,
belong to the acrodont division (Geosaurus, Acrosaurus, Homeo-
saurus, the last closely related to the modern Lacerta). The croco-
diles, with some partial exceptions (Streptospondylus, Theriosuchus),
belong to the primitive amphiccelous division (Teleosaurus, Mystrio-
saurus), or those in which there is a retention of the ichthyic char-
acter of bi-concave vertebra, as distinguished from the more modern
forms dating from the Cretaceous period, with proceelous (concavo-
convex) vertebre. The turtles, which appear here for the first time,
exhibit a remarkable differentiation, and in their diverse forms
comprise representatives of several of the more important modern
groups, as the Chelydz (Plesiochelys, Craspedochelys, Pleuroster-
non), Emyde (Thalassemys), and Chelydridw. The recent genus
Chelone is found in the Purbeck beds.

The most interesting addition to the fauna of this period is fur-
nished by the bird remains, whose earliest unequivocal traces are
. found in the famous Archopteryx of the Solenhofen slates of
South Germany (Bavaria), and in Laopteryx, from the deposits of
Wyoming Territory—the last a bird probably of about the stature
of a crane, but with uncertain affinities. The Archeopteryx, which
is known by two more or less well-preserved specimens, and a
feather pertaining to a third individual, combines in a most ex-
traordinary manner what have generally been considered distinc-
tively avian and reptilian characters, and, indeed, the animal may
be regarded as a type intermediate between the two classes. Thus,
in many points of structure of the skull and trunk, no less than in
the structure of the tail, which was greatly elongated and made up
of numerous distinct vertebra, it is decidedly reptilian, and this
relationship to the class of animals next lower in the scale of organ-
isation is borne out by the discovery, recently made by Professor
Dames, that the extremities of both jaws were provided with a num-

JURASSIC FAUNA. 165

ber of diminutive teeth implanted in sockets. But, on the other
hand, the animal, which was of about the size of a rook, was pro-
vided with powerful wings, and these wings no longer consisted
simply of a tegumentary membrane, as in the case of the bats and
the extinct pterodactyls, but were made up of feathers as in living
birds, a character indicating that the animal provided with them
was warm-blooded. Feathers were also developed in pairs on
either side of the tail; but the rest of the body, according to Vogt,
appears to have been completely naked.

The mammalian remains of the Jurassic period consist princi-
pally of teeth and jaws; in a more or less complete state of pre-
servation, whose characters indicate animals of diminutive size,
pertaining wholly or in principal part to the order of the Marsu-
pialia, or pouched animals. Both the insectivorous and the her-
bivorous types had their representatives, the former in such genera
as Amphilestes, Phascolotherium, and Amphitherium, and the lat-
ter in Plagiaulax; and it is not impossible that the more strictly
carnivorous type of marsupial also then existed. Stereognathus,
further, presents us with the type of a hoofed herbivore, and points
to a possible origin of the modern placental ungulata. Thus, the
marsupials had, as early as this period, attained a considerable de-
gree of differentiation, though apparently less considerable than
that exhibited by them at the present time. Latterly, some natu-
ralists, and notably Professor Marsh, have attempted to show that
these most ancient mammals of the Triassic and Jurassic periods
were not true marsupials, as these are now recognised, but that they
constitute distinct orders, Allotheria and Pantotheria, apart by
themselves; there do not appear to be sufficient grounds, however,
for the separation here proposed.

In the invertebrate fauna of this period we see, even more than
in the vertebrates, the reflection of the fauna of the period preced-
ing, but with the predominant features very largely extended.
These are in the main constituted by the mollusks, and more par-
ticularly by the cephalopods, lamellibranchs, and gasteropods, the
brachiopods (Rhynchonella, Spiriferina, Terebratula, Terebratella),
although still sufficiently abundant, no longer having that para-
mount importance which distinguished them as perhaps the most
distinctive type of the Paleozoic faunas. The cephalopods still
belong, in the main, to the types of the nautilus, ammonite (Amal-

166 GEOLOGICAL DISTRIBUTION.

theus, Arietites, Harpoceras, Agoceras, Stephanoceras, Lytoceras,
Phylloceras), and belemnite ; but representatives of groups that
appear to have been closely related to the modern calamary (Belo-
teuthis, Belemnosepia, Teuthopsis) are not exactly wanting. The
lamellibranchs and gasteropods comprise a most varied assemblage
of forms, many of them but barely distinguishable from individual
forms living at the present day, and by their great numerical de-
velopment give a generally modern aspect to the fauna. Of the
former the modern families Ostreidw, Limide, Mytilide, Astartida,
Lucinide, and Cardiidw are remarkable for their profuse develop-
ment, and scarcely less so the now nearly extinct Trigoniade and
Pholadomyidew; of the latter, the more important families are still
the non-siphonated ones (Pleurotomariidxz, Naticide, Trochide,
Actzeonide); but a no inconsiderable representation of the Siphon-
ata (Cerithiide, Aporrhaidw, Strombidx, Purpurida) is also inter-
spersed. The earliest fresh-water univalves belong to this period
(Paludina, Melania, Neritina, Planorbis).

The corals, which are of the type of existing star-corals, may be
considered next in importance to the Mollusca, and, indeed, in
some instances, as in the Coralline Oolite, they constitute by their
own vast numbers the greater portion of the solid rock, not im-
probably the vestiges of ancient reefs. Somewhat less important,
but yet very abundant in certain localities, are the fragments of the
Crinoidea, which are most distinctively represented by the genera
Apiocrinus and Extracrinus, the latter having its modern analogue
in the Pentacrinus of the Carribean Sea; but this comparatively
little specialised group of the Echinodermata has, ever since the
close of the Carboniferous period, been on its decline, and has left
its place to be filled by the true urchins (Cidaris, Hemicidaris,
Holectypus, Echinobrissus, Clypeus, Collyrites) and brittle-stars
(Ophioderma, Ophiurella, Ophioglypha), both of which, but more
particularly the former, now for the first time acquire any special
importance. The star-fishes are represented, among other forms,
by the type of the modern Uraster. Of the articulates there is a
considerable development of the Crustacea—crabs, lobsters, and
their allies—and in the fine-grained rocks the remains of centipedes,
spiders, and true insects are not uncommon, the last comprising
representatives of all the recognised modern orders. To this period
belong the earliest Diptera, Hymenoptera, and Lepidoptera.

JURASSIC FAUNA, 167

Turning to the flora, we find it to be sharply defined from that
of any of the Paleozoic periods, although in the abundance of ferns,
many of them of ancient type, and in the absence of the higher
forms of plants, it shows an interesting correspondence. Its most
marked feature is furnished by the group of the Cycads, of which
there are numerous genera recognised, and the pines, whose nearest
allies appear to be the southern araucarias. The earliest undoubted
representatives of endogens are found in the deposits of this age,
some of them clearly indicating a close relationship with the Aus-
tralian screw-pines (Pandanus). No positive traces of exogenous
plants other than conifers have as yet been determined, but it is by
no means improbable that they already existed.

Comparing the fauna and flora of the Jurassic period with the
existing fauna and flora of any portion of the earth’s surface, we
remark a striking similarity to the conditions presented on the
Australian continent. Here, at the present day, is the home of
the marsupials, of the Port-Jackson shark, which had its Jurassic
representatives in genera like Acrodus, Hybodus, and Strophodus,
and of Ceratodus among the lung-fishes, a form which, though of
more ancient date, also had its habitat in the seas of the Jurassic
period. Only along the Australian coast do we mect at the present
time with the lamellibranchiate genus Trigonia, one of the most
characteristic and abundant of the Jurassic mollusks. As regards
the flora, a no less striking correspondence is apparent. On the
Australian land-surface flourish a considerable variety of ferns, tree-
ferns, and cycadaceous plants ; likewise, the Araucaria tyne of
Conifer; and here, principally, do we find the singular plants al-
ready referred to as screw-pines (Pandani). Australia is, in fact,
that portion of the earth’s surface which, as far as its faunal and
floral characteristics are concerned, has undergone the least modi-
fication since the Jurassic period, and, indeed, it may be said that
the present fauna and flora of the continent became differentiated
during the interval between the Triassic and Jurassic periods, al-
though, as has already been seen, some of the distinctive types date
from a more ancient epoch. The retention of an ancient type of
fauna and flora clearly indicates that the continent had retained its
isolated position through a period probably extending as far back
as the Mesozoic era; otherwise, if connection with some other
continental land-mass. had existed at some subsequent period, it

168 GEOLOGICAL DISTRIBUTION.

would be barely possible that an interchange between the faunal
and floral characters of that land-mass and Australia should not
have been effected to a greater extent than is indicated by the
isolated position, especially of the fauna, now existing.

Cretaceous Fauna.—The Cretaceous period presents in many
respects a marked contrast in its faunal characters to the period
preceding. While many of the most important or characteristic
of the Jurassic invertebrate types still persist, in many cases with
undiminished or even increased force, as, for example, the differ-
ent classes of the Mollusca, we meet here with a development
of other animal groups which in most of the periods preceding
were of comparatively insignificant import. Such are the Fora-
minifera, which in their various forms (Globigerina, Rotalia, Tex-
tularia, Cristellaria) build up by their remains the great mass of
the chalk rocks, whose enormous extension is one of the most im-
posing monuments presented to the geologist. The sponges (Si-
phonia, Jerea, Thecosiphonia, Ventriculites) here likewise find their
greatest development, some of the forms having their analogues in
the types that still inhabit the oceanic depths; and the same has
been shown to be the case with the Cretaceous urchins (Echinoidea),
which are represented in great multitude and variety—Cidaris,
Ananchytes, Galerites, Micraster, Discoidea. The corals are in
comparison feebly developed, and can by no means claim that im-
portance which they obtained in the Jurassic period. The Belem-
nitide (Belemnites, Belemnitella) and Ammonitide still constitute
the most important of the cephalopod types, the latter especially
presenting a very considerable number of characteristic forms, the
so-called unrolled ammonites—Crioceras (with Ancyloceras and
Toxoceras), Hamites (Ptychoceras), Scaphites, Turrilites, Helico-
ceras, and Baculites.

The bivalve and univalve faunas, while largely made up of
Jurassic types, show a marked advance over the corresponding
faunas of the period preceding in the much greater development of
the siphonate forms. The Sinuata among the former, which, if we
except the very abundant family of the Pholadomyide, had hitherto
but scattered representatives, now acquire considerable importance,
especially in the families Veneridx, Tellinide, Glycimeride, Ana-
tinide, Mactride, and Myide. Among the non-sinuate forms
the members of the oyster family (Ostrea, Exogyra, Grypheea) and

CRETACEOUS FAUNA. 169

the scallops (Pecten), and the genus Inoceramus among the Hetero-
myaria, are distinguished by their numbers; but the most charac-
teristic elements of the lamellibranch fauna are furnished by two
families of very inequivalve-shelled mollusks, the Chamids, with
the genera Requienia, Monopleura, Caprina, and Caprotina, and
the so long misunderstood Rudistze (Spherulites, Radiolites, and
Hippurites), whose forms so eminently characterise the southern
belt of European and American Cretaceous deposits, and which ap-
pear and disappear with this period. The siphonate univalves have
an almost exclusively modern aspect, and comprise among others
representatives of the families Fuside, Strombidz, Muricide, Tri-
tonide, Buccinide, Cancellariide, Pleurotomidz, Conide, Olivide,
and Cypreide.

Turning to the vertebrates, we find in the lowest class, Pisces,
the introduction for the first time of teleosts, or true bony fishes,
that ichthyic group which at the present day surpasses, both in
individual members and variety, all the other orders of fishes put
together. These earliest teleosts, although not very abundant,
comprise a considerable number of modern types (Clupea, Esox,
Osmerus, Beryx); but it is not till the Tertiary period that they
acquire any well-marked development. No amphibian remains
have been detected in any Cretaceous deposit. Reptiles, on the
other hand, are exceedingly abundant, and comprise most of the
types whose existence has been indicated in the Jurassic seas.
Thus, of the modern groups, we have turtles, lizards, and croco-
diles (of both the amphiccelous—Hyposaurus—and proccelous types
—Holops, Gavialis), and, in addition, the first true serpent (Si-
moliophis). The extinct orders Ichthyosauria and Plesiosauria
are still represented, and in Elasmosaurus, belonging to the lat-
ter, we meet with one of the most formidable types of the finned
Reptilia. Here, also, are found some of the most gigantic of the
Dinosauria—Iguanodon, Megalosaurus, Hadrosaurus, Camarasau-
rus—and the remarkable group of the Pythonomorpha, or ‘“sea-
serpents ’—Mosasaurus, Leiodon, Clidastes—which in several re-
spects united the characters of both serpents and lizards. The
largest of the pterodactyls, or flying reptiles, having an expanse
of wing of from twenty to twenty-five feet, or even more, occur
in deposits of this period, and are represented by the normal-
toothed types, and by such, as the American Pteranodon, in which

170 GEOLOGICAL DISTRIBUTION.

the jaws appear to have been encased in horn, and to have been
entirely edentulous.

Bird remains are sufficiently abundant in certain localities, many
of them belonging to forms seemingly not very far removed from
some of our modern groups. But, in addition to these ordinary
forms, we have some of the most extraordinary of any that have ever
been described, and which, from the presence of true teeth in their
jaws, have received the name of Odontornithes (toothed-birds). In
the genus Ichthyornis, as exemplified in I. dispar, which was of
about the size of a pigeon, in addition to the peculiarity of alve-
olar teeth that of biconcave vertebre is presented, a structure of
the vertebral column characteristic of fishes and many of the ex-
tinct reptiles, but not known in modern birds. The wings ap-
pear to have been well developed, and in this, and all other respects
beyond those just mentioned, the animal conformed strictly to the
modern type of bird structure. In the still more remarkable Hes-
perornis, which in the species H. regalis attained a height of five
or six feet, the teeth, instead of being implanted in distinct sockets,
were placed in a continuous groove; the extremity of the upper jaw
appears to have been bent down in the form of a beak, and to have
been edentulous. The breastplate was entirely destitute of a keel
or ridge for the attachment of the powerful muscles required for the
motion of the wings, so that the bird was doubtless completely de-
nied the power of flight. The presence, in the same geological
period and the same geographical area (Kansas), of two birds so
closely related to each other in the presence of jaw-teeth, and yet
so distantly removed from each other by other peculiarities of
structure, argues strongly for the antiquity of this class of animals,
and, though the earliest unequivocal traces of birds have thus far
been met with in the deposits of the Jurassic period, it is more than
probable that their first origin is considerably more ancient.

No traces of any mammalian have thus far been discovered in
any indisputably Cretaceous deposit, a circumstance in great part
attributable to the particular conditions under which most of the

“deposits of this period, as known to us, were laid down, namely,
their marine origin. But there can be no doubt that at some future
day such remains will be found, and, indeed, if the deposits of the
Laramie age be conceded to be absolutely Cretaceous, as is claimed
(although on most contradictory evidence) by many geologists, then

CRETACEOUS FAUNA. ihe

the first of such remains, the Meniscoessus, has quite recently been
discovered. As now generally recognised, the Laramie deposits
constitute a series intermediate between the Cretaceous and the
Tertiary, the faunal characters, as are principally indicated by the
abundant remains of dinosaurian reptiles, pertaining to the former,
while the plants point directly to the latter. The angiospermous
exogens, whose earliest undoubted remains occur in the Upper
Cretaceous deposits, here undergo a very considerable devclop-
ment, and may, indeed, be said to represent the stock whence the
floras of the subsequent Tertiary and existing periods have been
derived. We find here many of our most common modern types,
such as the oak, beech, poplar, tulip-tree, magnolia, alder, and
plane.

Tertiary Faunas.—With the close of the Cretaceous period and
the beginning of the Tertiary, we note the most marked of all the
organic changes that characterise the different geological epochs.
Whole series of animals, from the lowest almost to their highest di-
visions, suddenly become extinct, or so nearly verge on extinction
as to constitute but a very insignificant element in the succeeding
fauna; on the other hand, groups of equal or greater importance,
and which had hitherto no (or but very scanty) predecessors, just as
suddenly make their appearance. It would seem as though a fresh
start had been taken in the peopling of the earth’s surface, so
different in many respects are the faunas of the Cretaceous and
Tertiary periods. But this difference, as it now presents itself,
must not be taken to indicate that it in fact even existed as such.
The gaps that now separate the one fauna from the other were un-
doubtedly filled by animal types of intermediate grade, of whose
existence we shall only be made cognisant when the hiatus which
here breaks into the continuity of the geologizal system will be more
completely filled in. It is illogical, and directly opposed to the
workings of evolutionary force, to conceive of a wide-spread group
of animals suddenly appearing and springing into prominence ;
and no less illogical to conceive of an equally sudden extermina-
tion. Hence, where vast differences in the faunas of any two suc-
ceeding geological periods present themselves, we have reasona»le
grounds for concluding that a long lapse of time has intervencd
between the close of one period and the commencement of the
period (as represented) next succeeding—in other words, that there

172 GEOLOGICAL DISTRIBUTION.

is here a geological break. Only there where the continuity of the
geological system is complete, or where the imperfection of the
record is reduced to insignificance, can we hope to meet with an
organic chain whose continuity is likewise complete. No such
complete record, or anything approaching it, has as yet been dis-
covered, nor is it at all likely that one will ever be discovered. But
the gaps in the record that occur in one locality or country may
be wanting in another, those present here be absent in the third,
and so on; hence, by a series of comparisons made between several
localities, we can in a measure realise a comparatively perfect
record, or at any rate one in which the breaks have been materially
narrowed, and with it also a comparatively perfect organic chain.
Except possibly in one or two regions of the earth’s surface, New
Zealand and California, nothing that may be said absolutely to
link together the Cretaceous and Tertiary deposits, at least those
of the marine series, has as yet come to light; the faunas are
largely distinct, and their distinctness is the index of the inter-
val that separates the outgoing of the one and the incoming of the
other.

The Tertiary fauna presents to us a clearly modern aspect, and
one that characterises all the animal groups represented, from the
lowest to the highest. And the farther we advance in this period
the more modern becomes the general faunal facies, so that in the
Pliocene, or uppermost division, not only are the genera largely
identical with existing ones, but (if we exclude the vertebrates)
also the species, notably among the mollusks. It may be stated
in a general way that all the more comprehensive of the animal
groups now existing are represented in the Tertiary deposits, and
the majority of these date from the Eocene, or earliest division. We
have no longer representatives of those wonderful reptilian orders, the
Ichthyosauria, Dinosauria, Pythonomorpha, and Pterosauria, which
characterised the greater portion of the Mesozoic era, and continued
to its termination; nor do we find any vestiges of the scarcely less
wonderful birds of the odontornithic group,* or of the type rep-
resented by Archeopteryx. Both reptiles and birds belong to

* An exception may, perhaps, be made in favour of the Odontopteryx, de-
seribed by Professor Owen, which has the substance of both jaws developed into
well-pronounced scrrations (or false teeth), an exaggeration of the character
exhibited by ducks and geese, to which the bird appears to bave been related.

TERTIARY MAMMALIA. 1S

the type of existing orders, and the same may be said of the fishes,
principally teleosts. The change in the character of the inverte-
brate fauna is somewhat less marked than in the case of the verte-
brates; but yet certain important differences present themselves.
Thus, among the acephalous and gasteropod mollusks, by far the
greater number, in fact nearly all the types, are referable to exist-
ing families, and even in the oldest division, the Eocene, to exist-
ing genera, or to such as are very closely allied to them. Such
characteristic families as the Hippuritide and Caprotinide, among
the bivalves, have completely disappeared, and, if we except some
half-dozen or more species found in Australian Tertiary deposits,
the same may be said of the Trigoniade, as well as of the Am-
monitide * and Belemnitide among cephalopods, about the most
distinctive of the invertebrate forms of the entire Mesozoic series.
Among the Tertiary invertebrates must be noted the extraordinary
development of the foraminiferal forms Nummulites and Orbitoides,
which, by their prodigious numbers, make up some of the most
stupendous deposits known to us. But that feature of the Ter-
tiary fauna which above all others arrests attention is constituted
by the class Mammalia.

The most striking fact that presents itself in connection with
the history of these animals is their very sudden introduction, both
as to individual numbers and diversity of form, almost with the
beginning of the period, a circumstance of no little significance when
it is remembered that, in the period preceding, if we except the
doubtfully placed Meniscoessus, not even a trace of their existence
has been detected, and that all such forms as have been found in
the earlier Jurassic and Triassic deposits belong, as far as we are
able to determine, to the single order of the Marsupialia. In the
earliest division of the Tertiary, the Eocene, on the other hand,
we meet with the remains of individuals belonging to at least one-
half of all the recognised orders of the present day.t Thus, we
have marsupials of the opossum type (Didelphis), insectivores,
rodents (as represented by the Sciuride, or squirrels), cetaceans

* A few ammonitic fragments have been found in the Tertiary deposits of
the Tejon group of California, and a Tertiary belemnite is claimed for Aus-
tralia.

+ The Ornithodelphia, Edentata, Proboscidea, Hyracoidea, and possibly
also the Sirenia and true Carniyora, are still unknown.

174 GEOLOGICAL DISTRIBUTION.

(Zeuglodon), ungulates, both odd-toed and even-toed (among the
former the tapiroid Lophiodon and Pal:eotherium, and other such
forms as Eohippus and Hyracotherium, which, through a series of
modified but closely-related types in the Miocene and Pliocene peri-
ods—Anchitherium, Hipparion—can be traced genetically to the
modern horse; and among the latter the possible ancestors of some
of the modern deer, Xiphodon and Anoplotherium, and the suil-
line Anthracotherium and Palzocheerus), bats, even of existing gene-
ra (Vespertilio, Vesperugo), lemurs, or lemuriform insectivores (Ada-
pis, Necrolemur), and not impossibly also the true monkeys. But
while most of the forms found in these earlier Tertiary deposits are
referable to modern orders, there are others which would appear to
have no place in the classification laid down for living forms, and
which combine, in many respects, the characters of two or more
orders. Thus, it has been convenient to designate an order Ambly-
poda for a line of animals which, at the one extremity, stand near-
est in their relationship to the Proboscidea, or elephants, and at an-
other to the odd-toed ungulates. In it are comprised the Uinta-
theria, ponderous tusked-animals, rivalling or exceeding in size the
modern elephant, and the coryphodons, considerably smaller ani-
mals of a generalised type, the probable progenitors of the last. A
still earlier type is embodied in the Condylarthra (Phenacodus),
from the very base of the Eocene, which represent the most primi-
tive type of known ungulate animals, and which not impossibly
are derivatives of some preceding hoofed marsupial. Another order,
the Tillodontia, has been established for certain animal forms which,
in several respects, combine the characters of the insectivores, ro-
dents, and edentates; and, again, a fourth order, the Creodonta,
for forms that seem to hold a position intermediate between the
insectivores and carnivores, and not unlikely represent the ancestral
line of the latter.

From the researches of paleontologists it would appear that
the primitive type of placental mammal is the insectivore, and
that from this original type have descended, by gradual modifica-
tion, most of the varied forms that now people the surface of the
earth, and those whose remains lie buried in the deposits of the
Tertiary period. At what precise period in the earth’s history the
Insectivora first appeared it is impossible to say, for, although no
remains occur in any deposits antedating the Eocene, there can be

-TERTIARY MAMMALIA, 175

little or no doubt, seeing what modifications of insectivore structure
are presented in the earliest deposits containing their remains, that
they appeared at a very much earlier epoch. The Tillodontia,
Creodonta, and Insectivora appear, as it were, simultaneously in
the Lower Eocene deposits, and if, therefore, they represent merely
modifications of one and the same structure, as is maintained by
Professor Cope, who has united the three groups into the one com-
prehensive order of the Bunotheria, then they must point to a com-
mon progenitor (foreshadowed in the Jurassic insectivorous marsu-
pials) removed far beyond the limits of the Tertiary period. Of
the three insectivore types here indicated, the true Insectivora,
which may be considered as the main or axial stem, have alone
survived to the present time. The Tillodontia and Creodonta both
became extinct before the middle of the Tertiary period, the latter,
however, by gradual modification passing off into the Carnivora,
whose earliest undoubted remains are to be found in the deposits
of Oligocene, or Miocene age. From the same group of the Insec-
tivora, although apparently at a somewhat later date than the Creo-
donta and Tillodontia, appear to have been descended the so-called
Prosimia, or primitive monkeys, the lemurs, whose earliest remains
occur in deposits of both Lower and Upper Eocene age; and to these
last, again, is doubtless to be traced the direct line of ancestry of the
various types of true monkeys that at the present day inhabit the
earth’s surface, and whose unquestionable traces are first met with in
deposits of Miocene age. The most important non-insectivore type
of Lower Eocene mammalian is the ungulate, whose remains, be-
longing to both the odd-toed and even-toed sub-orders, occur in
astonishing abundance, and argue very strongly in favor of a very
remote ancestory, one that may not impossibly carry us as far back
as the middle of the Mesozoic era.

The progressive modifications of structure which can be traced
through the more generalised of the Eocene mammalian groups
results in greater and greater specialisation the further we advance
in the course of time, and hence, in the Miocene period we meet
with more of distinctly specialised (or isolated) groups than in the
period preceding. In addition to the recent orders that have been
enumerated as belonging to the Eocene period we have the Eden-
tata (represented by such gigantic forms as Macrotherium and
Ancylotherium, whose nearest relationship appears to have been

176 GEOLOGICAL DISTRIBUTION.

with the aard-vark), the true Carnivora, Sirenia,* Proboscidea, and
Quadrumana. Per contra, most of the older forms have now com-
pletely disappeared, and, in fact, no mammalian order, with the
possible exception of the Creodonta (Hyzenodon), is indicated which
has not its living representatives at the present day. Most of the

INSECTIVORA

PLIOCENE

MIOCENE

(O4-G-O-C-E-N-E)

CREODONTA\ TILLODONTIA

EOCENE

BUNOTHERIA

CRETACEOUS

Uecrence-

DIAGRAM ILLUSTRATING RELATIONSHIP OF TeRTIARY MAMMALIA.

families are such as still exist, and even many of the genera are
identical, so that on the whole the mammalian fauna has a decidedly
modern aspect. The Miocene Insectivora comprise, among other
forms, representatives of the families of hedgehogs, shrew-mice,
and moles; the Rodentia, porcupines, mice, squirrels, rabbits, beav-
ers, &c.; the Cetacea are represented by true whales and dolphins;
the odd-toed Ungulata by the tapir and a number of allied tapir-
oids, and the singular giant forms that have been referred to the
not distantly removed family of the Menodontide (Symborodon,
Titanotherium); by true rhinoceroses and other forms (Hyracodon,
Aceratherium) closely allied to them; and by Equid#—Hipparion,
Miohippus (Anchitherium)—which differed from the true horses

* Eotherium Egyptiacum, from the Mokattam nummulitic limestone, is re-
ferred to this group by Professor Owen.

TERTIARY MAMMALIA. Bef

principally in size and the polydactyl character of the feet. Among
the even-toed ungulates we find the hippopotamus, the true swine,
deer, giraffe, and musk-deer, and, of the hollow-horned ruminants,
the antelopes—the sheep, goats,* and oxen being still absent, al-
though some of the antelopine forms would seem to effect a transition
between the true antelopes and goats. The Proboscidea comprise,
in addition to the true elephant (which, however, as a Miocene ani-
mal is known only from the deposits of the Siwalik Hills of India,
now frequently referred to the Lower Pliocene, or Mio-Pliocene),
the Mastodon, and the aberrant Dinotherium, which was provided
in its lower jaw with two prominent recurved tusks. The Carnivora
have yielded representatives of the cats—the true Felis and the
related sabre-tooths (Machairodus, Dinictis), the most formidable
of all known recent and extinct Carnivora—the weasels, civets,
hyenas (with the true hyena), and seals. The dogs are represented
by the genus Canis itself, and the more primitive Amphicyon,
through which a transition is effected to the ursine Hyznarctos,
and to the Pliocene true bears. Finally, the Primates have yielded
several genera, as Semnopithecus, Pliopithecus, and Dryopithecus,
the last referable to the group of the anthropoid or highest apes,
and fully equalling in size the human species.

Passing on to the Pliocene period, the mammalian fauna makes
a still further approximation to that of the present day in the in-
troduction of a number of modern types that had not hitherto made
their appearance, or only just appeared. Thus, we have here the
camel (in India), the ox, true bear (in Europe), and horse, in addi-
tion to most of the types that have been enumerated as belonging
to the Miocene period, and it may be broadly stated that the ma-
jority of the genera of this period are such as still exist, although
the species are in most cases distinct. The regions where Tertiary
mammals have been studied are principally the United States, Eu-
rope, and India, between whose faunas there is a well-marked cor-
respondence. While certain of the animal groups referred to are
found in the one region and not in the other, and are therefore
specially restricted, it may be said that approximately the same
groups are represented throughout, although the date of their ap-
pearance, or of that of their individual components, may be different
for the different countries. Thus, in the Upper Miocene, or older

* Capra Perimensis, from the island of Perim, is possibly a Miocene form.

178 GEOLOGICAL DISTRIBUTION.

Pliocene, deposits of the Siwalik Hills of India we have the true
hippopotamus, bison, bear, and elephant, forms which do not make
their appearance until a somewhat later date in Western Europe,
Pliocene, or Post-Pliocene. Similarly, the genera Cervus, Hystrix,
Felis, Hipparion, and Mastodon, which appear in Western Europe
in the Miocene period, are still wanting in the American continent,
making their first appearance in the Pliocene. And, likewise, the
true bears and oxen in Europe antedate the American forms by one
period. It may be stated, as a general rule, that where identical
genera of living forms occur in the deposits of both the Old and the
New World, those of the Old World are the more ancient; and the
same probably holds good, although to a less extent, with families.
From these differences in the dates of appearance of certain animal
groups, their presence or absence, we are led to discuss the probable
origin of our existing faunas, or portions of them.

The existence in Western Europe in Miocene, and especially in
Pliocene, times of a fauna consisting of forms which still inhabit
the region, and of others as are only to be found at the present time
on the continents of Africa and Asia, may appear at first sight
somewhat singular. But when we reflect that the climate, during
the whole or the greater portion of this period, was probably very
much more uniform and warmer than it is at the present time, and
possibly not very different from what it now is in the region of the
Tropics, the apparent singularity in great measure disappears.
Some of the tropical forms, as the giraffe and rhinoceros, may have
been indigenous to the region, while others, whose development in
South-Central Asia appears to have taken place at an earlier period,
not improbably represent immigrants from the heart of that con-
tinent. It is practically certain, moreover, that direct land commu-
nication existed during a considerable portion of this period with
the continent of Africa, with which, consequently, there would
have been effected a general interchange of forms. Indeed, it is
much more singular that Europe no longer retains its more charac-
teristic African forms; but it must be recollected that, with the
advent of the Glacial period, an era of cold set in, and that with
this inclement climate a general retreat southward took place, the
more tropically constituted animals passing over into the conti-
nent of Africa, or suffering extermination by the cold. The most
northerly animals, passing southward, occupied the region now more

ORIGIN OF EXISTING FAUNAS. 179

or less vacated by the tropical forms, and hence, in the deposits of
the Glacial and Post-Glacial periods, we meet with the remains of
the elk, reindeer, hyena, lion, giraffe, elephant, rhinoceros, and
hippopotamus mixed together. At about the same epoch it would
appear that the present rupture existing between the African and
European continents was effected, a separation which precluded the
possibility of a return migration from Africa when the more toler-
able climate succeeding the close of the Glacial period set in.
Hence the survival only of the more temperate forms of the Euro-
pean fauna. While Africa, therefore, retains its strictly African
mammalian forms, it may be considered questionable whether these
are not direct importations, in great part, from the region lying to
the north. As far as the North American continent is concerned, it
appears not improbable, from what has already been said with refer-
ence to the earlier appearance in Europe of equivalent mammalian
types, that a not inconsiderable portion of its later (fossil) fauna
was derived from the Old World. Thus, it appears likely that the
bears, swine, oxen, sheep, antelopes, and elephants originated in
the Old World, whence they were transplanted by way of some
land connection existing in the north into the New World. The
true dogs, on the other hand, seem not unlikely to have been de-
veloped first on the American continent; and it is also not improb-
able that the ancestral line of the camel is to be traced to the West-
ern Hemisphere. Our paleontological knowledge of the different
countries, even of those more thoroughly explored, is, however, far
too insignificant to permit of a definite solution to the problem of
the origination of the various mammalian groups, and in the case
of most continental faunas but little can be said with positiveness
concerning their formation. The North American continent lacks
in its Tertiary fauna the giraffe, hyena, and hippopotamus; nor do
we find any traces of the group of the Old World monkeys, or, in
the greater portion of the region, of the Edentata, whose various
forms are now so abundantly represented in the South American
fauna.

With the Post-Pliocene period the correspondence existing be-
tween the fossil and recent faunas of the several geographical regions
is in most cases further increased, and not only by the introduction
of many new modern genera, but by the presence, in considerable
number, of identical specific types. The modern fauna may now

180 GEOLOGICAL DISTRIBUTION.

be said to be broadly marked out. Thus, in the Australian Pleis-
tocene marsupials, Diprotodon, Nototherium, Thylacoleo, and their
allies, we have the forerunners of the various marsupial forms that
now characterise the continental fauna; in the giant birds Palapte-
ryx, Dinornis, Mionornis, &c., from New Zealand, and Apyornis
from Madagascar, the forerunners of the wingless apteryx and the
struthious birds from the same or neighbouring regions; and in
the giant South American edentates, Glyptodon, Megatherium, My-
lodon,* and their allies, the representative, if not the ancestral,
forms of the existing sloth, armadillo, and ant-eater. It is re-
markable that these last forms also occur in the Post-Pliocene de-
posits of the United States; but there can be but little doubt that
their presence there was the result of a temporary migration from
the south, since their remains are only exceptionally found in any
of the preceding Tertiary formations.

We have noted in the Eocene period the presence of a certain
generalised group of mammals, from which, by gradual modifica-
tions of structure, the more specialised groups of subsequent periods
have sprung. The demonstration of this successive evolution of
forms is not, however, restricted solely to groups of animals, but it
can be indicated with no less positiveness in the case of certain in-
dividual members of a group. The most notable instance of evolu-
tionary modification in a given line is afforded by the horse. Thus,
from the modern horse we can trace downward in the geological
scale a gradual series of modifications in the structure of the teeth
and limbs which, at the further end of the line, characterise an
animal so far removed in general structure from the existing form
that, were not the intermediate forms known, or were it to be con-
sidered by itself, it would be recognised not only as the type of a
distinct family, but of a distinct sub-order. From the solidungu-
late type represented in the existing form we reach, by sensible
gradations, an animal of the polydactyl type, or one having several
toes to each foot. A phylogenetic line, but little less complete, can
also be traced in connection with the families Camelidz, Tapiride,
and Felidx, and others, doubtless, will be discerned with the fur-
ther progress of paleontological investigation.

* The deposits containing these remains have been very generally consid-
ered to be Post-Pliocene; Ameghino and Cope, however, probably correctly
refer them either in whole, or in part, to the Pliocene.

Appearance and disappearance of species.— Reappearance.— Extinction.—Per-
sistence of type-structures.—Variation.— Geozraphical distribution.—Cli-
matic zones.—Sy nchronism of geological formations.

Ir is assumed by all, or nearly all, geologists, that every species
of animal, broadly speaking, had a definite belonging in the geo-
logical scale; in other words, that its existence was coincident with
a certain period in the development of the earth, and with no other.
Thus, the well-known and largely-represented brachiopod, Spirifer
disjuncta (Verneuilii), whose occurrence has been noted in North
America, throughout the greater extent of continental and insular
Europe, in Asia Minor, China, and New South Wales, is everywhere
restricted to the Devonian formation, and is, therefore, distinctive
of that period. Similarly, the no less widely disseminated Pro-
ductus semireticulatus, a member of the same group of animals, is
restricted to the Carboniferous formation. So limited, indeed, ap-
pears to have been, in most instances, the range in time of a given
species, that the inspection of a single well-determined form will
frequently fix, not only approximately but absolutely, the horizon
of the deposits whence it was obtained. Belemnitella mucronata,
one of the squids, characterises a definite horizon of the Upper
Cretaceous; and among the Ammonites we have numerous instances
of specific restriction to special “ zones” of even the minor divi-
sions of a formation. Limitation of range appears to pertain
more strictly to the members of the higher groups of animals than
to the lower, or to such forms whose complexity of organisation
might be supposed to interfere with a ready accommodation to
changing physical conditions of the surroundings. Not one of
about one hundred and twenty-five species of fish described from

182 GEOLOGICAL DISTRIBUTION.

the Old Red Sandstone of Great Britain appears to have lived on
into the succeeding Carboniferous period, whereas, of the Inverte-
brata, comprising the corals, annelids, echinoderms, crustaceans,
and the several classes of the Mollusca, the survivors of the Devo-
nian period number no less than twelve per cent. An equally
striking case is presented by the Mammalia, where, of the very
numerous forms that have been referred to the European and North
American Tertiaries, not one is positively known to have passed
either from the Eocene division to the Miocene or from the Mio-
cene to the Pliocene; and but a mere handful, if that, from the Plio-
cene to the period next succeeding, the Quaternary or Post-Plio-
cene. And yet we are aware that, in certain Eocene localities, no
less than five per cent. of the molluscan fauna has survived into the
present epoch, and as much as thirty to forty per cent. from the
Miocene! Turning to the Invertebrata themselves, we find among
the different classes no less striking confirmation of the law of the
persistence of the less highly organised specific types over those
more highly organised. Taking the sub-kingdom Mollusca, for
example, we find, from an examination of the carefully prepared
tables of Mr. Etheridge ® on British Paleozoic fossils, that, of the
three great classes whose members are not free-swimmers, and who
would be consequently most likely to fall under the influence of
special physical conditions, the erder of persistence is, in most
cases, Brachiopoda, Lamellibranchiata, and Gasteropoda—i. e., the
lowest first and highest last. Species of brachiopods range from
every one of the major formations to the formation next succeed-
ing, as from the Cambrian to the Silurian, from the Silurian to
the Devonian, from the Devonian to the Carboniferous, and from
the Carboniferous to the Permian. The Lamellibranchiata and
Gasteropoda, on the other hand, each pass but once from the De-
vonian to the Carboniferous. Looking at the numerical develop-
ment of the transgressional forms, we find that fourteen per cent.
of the Devonian brachiopod fauna reappears in the Carboniferous,
thirteen per cent. of the lamellibranch, and eleven per cent. of
the gasteropod. Of the equivalent polyzoan fauna the transgres-
sional forms constitute thirty-seven per cent.

Numerous instances of transgressional forms could be cited from
the other branches of the animal kingdom, but to no special pur-
pose. <As a rule, the number of such connecting forms is very

REAPPEARANCE OF SPECIES. 183

limited, and only in the comparatively very recent Tertiary epoch
do they acquire any marked significance. But, if the number of
survivors of any one epoch is very limited, it will naturally follow
that this number will be still further reduced if a question of two
or more epochs is involved. It was, indeed, for a long time main-
tained by geologists that no species of animal, no matter of what
form of organisation, could possibly have entered into the forma-
tion of three successive [epoch] faunas; for instance, that no species
appearing in the Silurian could live completely through the Devo-
nian, and then continue into the Carboniferous. And this notion
is still largely entertained by the geologists and paleontologists of
the present day. However much of truth there may be in such a
doctrine, it must be confessed that its acceptance or rejection will
depend, at least in some part, upon the standpoint from which the
investigator views the nature of species. There is, perhaps, nothing
that has more taxed the ingenuity of the naturalist than to deter-
mine just exactly what a species is, what constitutes its absolute
boundaries or limitations. The amount of disagreement upon this
point is so very great, even among naturalists holding approximately
the same views on genesis or evolution, that one might fairly despair
of arriving at anything like a just solution of the problem. During
the period when the doctrine of the immutability of species was a
common faith, there was, indeed, but little difficulty in the matter,
since every reasonably differing form was immediately constitut-
ed into a distinct species; and it is in this period that many, if
not most, of our existing paleontological notions have their roots.
Now, however, when the doctrine of descent by modification is
universally acknowledged as one of the great truths of nature, much
greater latitude is permitted to the definition of the word species,
and, in fact, what might at one time be considered as a good species
can, in the light of a newly-discovered chain of “ intermediate ”
forms, be readily degraded to the rank of a variety. Such has, in
truth, been the history of a great many so-called species. The
difficulty of determining specific longevity thus becomes apparent,
for who can state what will be the fate of forms that now stand
apparently far apart? However divergent may be the views of
authors on the matter of relationship, it is practically certain that
numerous forms of life, exhibiting no distinctive characters of their
own, are constituted into distinct species for no other reason than

184 GEOLOGICAL DISTRIBUTION.

that they occur in formations widely separated from those holding
their nearest of kin. Whether these be really good species or not
may be a matter for further consideration; but it cannot be denied
that their primary recognition as such is based upon the assumption
that no species, after it once became extinct, ever again came into
existence. While there is much that speaks in favor of this doc-
trine, it may, nevertheless, safely be asked, in what lies the proof
of its correctness? Surely we possess no knowledge which will
permit us to state just when a given species became extinct. Dis-
appearance from one locality is in itself no indication of absolute
extinction, any more than appearance is an indication of primary
origination. How, then, can we ascertain, when a given form
supposed to be extinct reappears after an interval of a formation,
whether that form in reality became extinct or not? It is usually
assumed that it did not, and its range in time is correspondingly
extended; or, the reappearing form, with no distinctive characters
of its own, is elevated to the rank of a new species, and the extinc-
tion of the first species insisted upon. But it is evident that this
method of forcing the point is in the nature of an argumentum in
circo, and leaves the question of extinction and reappearance in the
condition of ‘not proven.”

While, apart from the proof that is lacking in the matter, the
doctrine of non-reappearance seems to commend itself by a certain
‘‘ plausibility,” it may still be doubted whether this supposed
plausibility is not more a matter of preconception than of actual
fact. If evolution is true, and there are few among scientists
who would deny that it is so, can it not readily be conceived that,
as the result of the interaction of the physical and organic forces,
identical forms may have been evolved as the heads of very distinct
lines of descent ? And, if so, may not this process have operated
through distinct periods of time? Mr. Darwin, in attacking the
problem, thus states the case (‘‘Origin of Species,” p. 379, ed.
1866): ‘‘ We can clearly understand why a species, when once lost,
should never reappear, even if the very same conditions of life,
organic and inorganic, should recur. For though the offspring of
one species might be adapted (and no doubt this has occurred in
innumerable instances) to fill the exact place of another species in
the economy of nature, and thus supplant it, yet the two forms—
the old and the new—would noi be identically the same, for both

REAPPEARANCE OF SPECIES. 185

would almost certainly inherit different characters from their dis-
tinct progenitors. For instance, it is just possible, if our fantail
pigeons were all destroyed, that fanciers, by striving during long
ages for the same object, might make a new breed hardly distin-
guishable from our present fantail; but, if the parent rock-pigeon
were also destroyed, and in nature we have every reason to believe
that the parent-form will generally be supplanted and exterminated
by its improved offspring, it is quite incredible that a fantail, iden-
tical with the existing breed, could be raised from any other species
of pigeon, or even from the other well-established races of the
domestic pigeon, for the newly-formed fantail would be almost
sure to inherit from its new progenitor some slight characteristic
differences.” That the reasons here given satisfactorily explain
why, in the vast majority of instances, lost species should not reap-
pear, most naturalists will admit; but that they do not in them-
selves sufficiently explain why such reappearance may not occasion-
ally occur, may be reasonably contended. Thus, in the case of the
birds referred to, it would by no means be unreasonable to suppose,
even if such instances are a decided rarity, that the parent rock-
pigeon, through some special adaptation to surrounding conditions,
might have long survived the generations of fantails that were
primarily derived from it, and that, at some future period, after a
process of selection, a second series of fantails might have been
produced practically identical with the first. The irregular dura-
tion in length of time of species is well known to geologists, and
its importance as a factor in evolution has been insisted upon by
Mr. Darwin. It is probably true, as Darwin affirms, that ‘the
parent-form will generally be supplanted and exterminated by its
improved offspring ;” but it does not necessarily follow that the
offspring will invariably prove to be of an improved stock, and,
where this is not the case, there would be nothing very surprising
in the survival of the parental form. The tenacity with which cer-
tain specific characters adhere to some of the older genera, espe-
cially of mollusks, is so great that paleontologists are frequently at
a loss to determine. just what characters separate practically the
newest from the oldest species of a given genus. This is the case
with the Nautili, and with a number of the brachiopods. Now,
either we have here a retention through almost indefinite periods of
primary specific characters, or a reversion (or a series of reversions)

186 GEOLOGICAL DISTRIBUTION.

to a type once formed, but which has at one or more periods been
effaced. If the former, would it be illogical to suppose that some
of the numerous varieties or species that may have been evolved
during a long lapse of ages from the parental stock should have
proved less hardy than it, and should have, therefore, suffered much
earlier extinction or modification? And, if so, what is there that
we know that should absolutely prevent the same early extermi-
nated forms from being re-evolved? It will be naturally assumed
that the new and the old species, which appear to be so closely
connected, are in reality distinct, and this may be true in all cases;
but, if the distinguishing characters separating the two are almost
imperceivable, it will require not much stretching of scientific prin-
ciples to conceive that at least some of the resulting varieties may
be strictly indistinguishable.

Again, reverting to the case of the pigeons, it seems by no
means clear, although such results may be of very rare occurrence,
why a fantail, identical in every respect with the common form,
may not be produced from a species of pigeon other than the rock-
pigeon. It is true, as Darwin states, that newly-formed varieties
would be almost sure to inherit from their progenitors certain dis-
tinguishing traits or characters; but, as the formation of a species
will depend upon the overbalancing by newly-acquired characters
of those that may have been left by inheritance, there seems to be
no reason why, through a process of selection and adaptation, such
a convergence might not occasionally take place as would unite
the ends of very distinct lines of descent. Paleontologists have
long held to the opinion that the line of descent which leads up to
the horse (genus Equus) in America is different from the similar
line of Europe, and if it has been contended that the existing spe-
cies, Equus caballus, was not in itself a product of the American
line, but a modern European importation, its recent discovery in
the Post-Pliocene deposits of this country proves the erroneousness
of such an assumption. If, therefore, we are permitted to assume
that two distinct lines of descent, the one passing through Eohip-
pus, Orohippus, Mesohippus, Miohippus, Protohippus, and Plio-
hippus, and the other through Palseotherium, Anchitherium, and
Hipparion, lead up to an equivalent genus, the genus horse or
Equus, would it be unreasonable to suppose that, with a continu-
ance of the process of evolution, even the same species may be

PARALLEL DEVELOPMENT OF SPECIES. 187

evolved ?* And, if this is possible, seeing that under apparently
identical physical conditions the resulting genus became extinct
on the American side of the Atlantic, while it still flourished on
the European, might it not have so happened that the genus
should have actually become extinct on the one continent before
it even came into existence on the other? Assuming this condi-
tion, we should then have a true case of extinction and reappear-
ance, Similarly, in the case of the genus Tapirus, the tapir, it
is by no means certain that the eastern and western forms are not
the products of two distinct ancestral lines, independent in their
evolution of such influences as might have been brought about by
migration and interassociation.*™

It may, however, still be urged that the apparent development
of parallel lines on the two continents is not in reality such, and
that their independent convergence is merely the result of an inter-
mixture of Old and New World types, during a period of land
connection. That a union between the northern parts of the two
hemispheres may have existed during the Eocene, and again in the
Miocene and Pliocene periods, can very well be true, but that such
a union need not necessarily imply the absolute inter-derivation of
the two continental faunas can equally well be true. The complete
absence from one continent of some of the more abundant fossil
types occurring in the other, as the genera Paleotherium, Anoplo-
therium, and Lophiodon from America, and Oreodon from Europe,
proves that there must have been (granting land connection) some
formidable check to migration ; and this assumption is further
borne out by the circumstance of the irregular appearance in time,
on the two continents, of such animals as might readily be supposed
to have been able to grapple w.th a northern barrier.

* Orohippus has been identified by many paleontologists with Hyraco-
therium, and Miohippus with Anchitherium.—Waagen, from his studies of
the Indian Jurassic Ammonitide, has arrived at the conclusion that the genus
Aspidoceras (Ammonites auct. pars) has descended from at least two distinct
generic roots, and further maintains that the same duplex or multiple origin
can be traced in other genera as well (‘‘ Paleontologia Indica,” ser. ix., 4,
1875, p. 241). He also affirms that certain species of Phylloceras, as, for
example, P. ptychoicum and P. Benacense, common to both Europe and In-
dia, are the product, in the two countries, of distinct ancestral lines, con-
vergent modification, as ‘‘ dependent on laws which were innate’’ in the spe-
cies, having brought about an identical result (Joc. cit., p. 243).

188 GEOLOGICAL DISTRIBUTION.

Among the Invertebrata we have also, as has already been inti-
mated, well-marked instances of apparent reappearance. Mr. Da-
vidson, in his review of the British fossil Brachiopoda,®® affirms
that the resemblance between the recent Rhynchonella nigricans,
which has nowhere as yet been found in any Tertiary deposit,
‘‘and some Cretaceous and Jurassic forms is so great that we are
at a loss to define their differences.” And, further, that certain
varieties of the Mediterranean Terebratulina caput-serpentis, whose
range extends downwards only to the Pliocene, so closely re-
semble the Cretaceous Terebratula striata as to render the two
barely, if at all, distinguishable. It may be that at some future
date intermediate links will be discovered to unite the forms of
the two periods; but who can, in the meantime, affirm that these
are not true cases of reappearance ? If it is true, as M. Barrande
asserts, that the Triassic Nautilide show less affinity to existing
species than do the primitive forms —#in other words, that the
recent species are more closely related to the original forms than
the forms of a half-way intermediate period—are we not justified
in assuming that there is here a reversion, or tendency towards a
reversion, to specific characters once lost ?- Among the Foraminifera
we have several notable instances of apparent specific longevity, as,
for example, the recurrence in the modern seas of some of the cre-
taceous species of Globigerina, Cristellaria, and Glandaria; and, not
unlikely, seeing how very slow must of necessity be the variation
in this class of animals, by reason of their ready adaptability to their
surroundings, the same forms will, on future investigation, be found
to date considerably further back in the geological scale.

It must not be construed, from the preceding argument, that
we have attempted to prove the frequency of specific reappearances.
These, if they actually have existed, which is not unlikely, were,
doubtless, of exceptional occurrence, and in no way affect the prob-
lem of progressive development. It might be objected that, if the
views here set forth are correct in their application to species, they
must also apply in a corresponding degree to some of the higher
animal groups—genera, for example. This is certainly true, and,
indeed, it may well be asked, What insuperable obstacle is there,
that we know of, that should absolutely prevent the occasional re-
appearance of a lost genus? Assuming, with many paleontologists,
that Goniatites is a genus evolved from Nautilus, either directly or

REAPPEARANCE OF GENERA. 189

indirectly, what is there, in view of the persistence of the nautiloid
type, to preclude the possibility of the same genus being re-evolved ?
There may be a sufficiency of reasons with which we are not ac-
quainted ; but if, with our present limited knowledge, we are unable
to indicate what these may be, it is scarcely fair to insist, a priori,
upon their existence. It is true, we have no special reasons for as-
suming why the Nautilus should become modified into a Goniatites;
but this of itself is no proof that it may not. Numerous instances
of genera widely separated by formations in which no representative
of their tribe is to be met with are known to every paleontologist,
but perhaps no more remarkable example is presented than that
of the genus Nummulites. It has been well said by Mr. Brady ™
that ‘‘there are few time-marks in the geological record that have
been regarded as better established, or more definite, than the first
appearance of the Nummulite, at or near the commencement of the
Tertiary epoch,” and so little, in fact, is known of any of the ante-
cedent forms, that many, if not most, paleontologists of the present
day still hold to the correctness of the view here stated. The re-
searches of Giimbel and Brady have, however, placed beyond all
doubt the existence of at least one Jurassic species (Nummulites Ju-
rassica, Franconia) and one Carboniferous (N. pristina, Belgium),
and not unlikely a somewhat doubtful form, N. variolaria, var.
prima, described from the Cretaceous rocks of Palestine, will, on
further investigation, prove to be a true member of the genus to
which it has been referred. That we have here an instance of
generic reappearance it is impossible to affirm, but it is certainly
almost inconceivable, whichever way it be considered, that a group
of animals, so extensively developed as are the Nummulites in the
Tertiary deposits, should have left practically no traces of their

xistence behind them in the deposits next preceding the Tertiary,
the Cretaceous, when their ancestry dates so far back as the Car-
boniferous epoch. It is scarcely possible that at no period of time
between the Carboniferous and Tertiary epochs should the condi-
tions for their development have been favourable; and equally im-
probable does it appear that, if such development actually did. take
place, we should so thoroughly lose sight of their remains. Grant-
ing the absolutely unfavourable conditions, however, can it be
readily imagined that a few miserable forms, evolved at an entirely
unpropitious moment, should have battled through the struggle for

190 GEOLOGICAL DISTRIBUTION.

existence to develop after an interval of millions of years? This
seems very improbable, but yet it may be so; but why may it not
also have been that, in the Carboniferous form, we had prema-
ture evolution, with subsequent extinction, and that at a much
more recent period a re-evolution of the same form, under more
favourable circumstances, took place? The case is certainly very
extraordinary, and probably has no parallel in the history of pale-
ontology.

On Appearance and Extinction.—It would naturally be sup-
posed on the hypothesis of evolution that the introduction of all
species must be a very gradual one, for it can scarcely be conceived
that the laws governing the formation of new species through de-
scent and modification could be anything but very slow in their
action. So true is this, that Darwin has himself admitted, that
‘‘if numerous species, belonging to the same genera or families,
have really started into life at once, the fact would be fatal to
the theory of descent, with slow modification through natural se-
lection ” (‘‘ Origin of Species”). Yet if we glance over the geo-
logical record we cannot fail to note a very considerable num-
ber of seemingly flagrant contradictions, groups of allied species
appearing in almost every formation with apparently the greatest
possible abruptness. We have but to instance as examples the
genera of articulate brachiopods, and the tabulate corals of the
Silurian period, the ganoid fishes of the Devonian period, the
Tertiary placental mammals, and the foraminiferal genus Num-
mulites, already referred to. Probably there exists no more strik-
ing illustration of the abrupt or sudden development of a family
than is furnished by the Nautilids. a group of animals for whose
elucidation we are principally indebted to the labours of M. Bar-
rande. Of this family of cephalopods, which comprises probably
upwards of two thousand distinct species, no less than four hun-
dred and sixty-three species, referable to some fifteen or more
genera, are already represented in the Lower Silurian formation,
although from the preceding Cambrian deposits at best only two
well-authenticated forms (Cyrtoceras preecox and Orthoceras seri-
ceum) are known. Of this number about two hundred and sixty
belong to the genus Orthoceras itself, ninety to Cyrtoceras, and
forty-six to Endoceras, the last, a genus restricted absolutely to
the Lower Silurian deposits. Facts such as these have been eager-

APPEARANCE AND EXTINCTION. 191

ly seized hold of by the advocates of the doctrine of independ-
ent and successive creations as proving the fallacy of any slow
modification theory of transformism, and were it not that they are
in themselves fallacious, would alone be sufficient to overthrow any
such theory. For not alone must of necessity the development of
a group of forms, all of which were descended from some one pro-
genitor, have been an extremely slow process, but the ‘‘ progenitors
must have lived long ages before their modified descendants.” The
experience of every paleontologist proves to him, however, how
misleading are those apparent abrupt appearances, and how very
frequently groups of forms, supposed to be restricted to a definite
horizon or formation, suddenly appear in a region perhaps not
hitherto worked over, or, even where the work of the geologist has
been accomplished with a sufficient amount of care, in a horizon
of considerably older date. Almost every large group of animals
furnishes such instances of antedating. No fact was at one time
considered to be more firmly established than that the Mammalia
belonged exclusively to the Tertiary and Post-Tertiary epochs, and
yet we now know of their existence, even in considerable variety,
in the deposits of both Jurassic and Triassic age; the serpents,
which until quite recently were thought to have their earliest
ancestors in the deposits of the Tertiary age, have been traced
back to the Cretaceous (France); the Insecta, whose supposed
earliest appearance in the Carboniferous rocks was considered to
mark an epoch in the faunal development of that period, have, in a
series of impressions left in the Devonian shale of New Bruns-
wick, proved their existence at a much earlier date, and only with-
in the past year, 188485, the announcement is made of the dis-
covery of scorpion remains in the Silurian rocks of both Sweden
and Scotland. It will still be in the memory of many geolo-
gists and paleontologists with what startling effect the announce-
ment of the discovery of the first air-breathing vertebrates in the
deposits of the coal was made, at the very time when the absence
of such forms was ascribed to the impossibility of their breathing
an atmosphere supercharged with carbonic acid! In the case of
special genera we have equally well-marked instances of anteda-
ting.

Waagen’s discovery of an ammonite in the Carboniferous rocks
of the Salt-Range of India was for a long time discredited, so firmly

192 GEOLOGICAL DISTRIBUTION.

had the notion that the ammonites were restricted to the Mesozoic
era been engrafted on the minds of paleontologists; but now, sev-
eral individuals, belonging to two or more species, have been ob-
tained from the same deposits, and one closely related form has
been quite recently described from the nearly equivalent deposits
of Texas. M. Barrande has laid great stress upon the sudden ap-
pearance, side by side, and in the full plenitude of their characters,
of the more distinctive genera of cephalopods (Orthoceras, Cyrto-
ceras, Nautilus, Trochoceras, Bathmoceras) in the first aspect of
his second Silurian fauna (Lower Silurian of geologists generally),
and their complete absence from the Primordial Zone (Cambrian) ;
but we have seen that at least two of the genera, Orthoceras and
Cyrtoceras, have since been traced back to the earlier formation.
Almost every chapter in geological history indicates some such case-
of antedating, and proves to the paleontologist how very cautious
he should be in his limitation to time of particular groups of or-
ganisms. It cannot be expeeted that in any portion of the earth’s
surface will there ever be found a complete sequence of the geologi-
cal formations, nor can we hope satisfactorily to bridge over in all
cases the gaps that occur in one locality with the deposits found
in another. The unequal period of time during which land areas
have been laid dry or been kept submerged beneath water, in con-
junction with the devastating effects of denudation, render such a
complete restoration of the series impossible, and as long as this is
so, the work of the paleontologist must inevitably be riddled with
‘‘breaks” in the geological record. It is surprising, in view of
these facts, which are too obvious to be overlooked, with what
tenacity some paleontologists insist upon absolute limitation of
species, or groups of species, and how slow they are to accept any
new facts bearing upon distribution in time that might in any
way disturb the harmony of their preconceived notions. There is
perhaps no more patent fact in the history of the physical de-
velopment of our planet than the imperfection of the geological
record, the full realisation of which could not fail to dispel many
of the singular notions that still prevail relative to the support
which paleontology brings to the doctrine of evolution.
It has been objected that, in assuming the universality of breaks,

we are drawing largely upon our fancy, and that conditions which
do not exist in fact are arranged to suit the views of the evolution-

PALEONTOLOGICAL BREAKS. 193

ist. This may be true in a limited number of cases; but there is
every reason to believe that the constancy of breaks is even far
greater than the most enthusiastic advocate of the doctrine of im-
perfection would be ready to admit. For, even in such areas where
the rock-masses through a general uniformity of character would
seem to indicate continuous sedimentation, have we always definite
proof that the sedimentation was really continuous? Far from it.
If, for example, certain parts of the Atlantic border of the United
States were depressed beneath the sea, and a new Post-Tertiary
deposit imposed upon them, we might be not a particle the wiser,
as far as stratigraphical and lithological evidence went to show, for
the enormous period of time that intervened between the formation
of the newest and next newest (Miocene) series of deposits. The
strata would lie practically conformably on one another, and it would
require but little degradation to plane down these inequalities,
which would otherwise indicate an eroded land surface. The mem-
bers of the Cretaceo-Eocene series of the State of New Jersey, and
elsewhere along the same coast, are so intimately related to one an-
other, by conformability of position and lithological structure, that
it might readily have been assumed that we had here an instance of
continuous sedimentation; and, indeed, fora long time no division-
line was supposed to exist. But the unmistakable evidence of pale-
ontology proves that here, as well as at most parts of the earth’s
surface which have been made accessible to the geologist, a break
marks the junction of the Cretaceous and Tertiary formations.

It must be admitted that there are certain anomalies connected
with the occurrence of breaks which have not thus far received an
adequate explanation. Their broad distribution—it might, indeed,
almost be said universality—in equivalent periods of time, has long
been noted as a surprising fact, and one that still remains in the
nature of a puzzle to the geologist. Nowhere on the surface of the
earth has there as yet been found a distinct connection between the
Paleozoic and Mesozoic series of deposits, and only at a very few
points (India, New Zealand, California) what may be considered to
be an unequivocal link between the Mesozoic and Cainozoic series
(Cretaceous and Tertiary). It is true that the field surveyed by the
geolcgist is of comparatively limited extent, when compared with
that which still remains to be explored—the greater part of the conti-

nents of Asia, Africa, South America, and Australia—and it is but
oS

194 GEOLOGICAL DISTRIBUTION.

reasonable to expect that, in some of the regions here indicated,
the connections will be found that elsewhere are wanting. But,
even granting the justice of this plea, the facts, such as they are, are
of themselves sufficiently remarkable, as indicating how very far-
reaching in their action must have been the forces that were directly
concerned in the causation of breaks. It is a little difficult to con-
ceive of secular elevations and depressions of the land-surface ex-
tending simultaneously over nearly the entire circumference of the
earth, even in the restricted area of the Temperate Zone; but such
must undoubtedly have been the case to account for the phenomena
that are presented to us. Otherwise complete passage-beds would
be of much more frequent occurrence than we know them to be.
This does not preclude the possibility of the existence of local areas
showing a differential or contrary movement; such, however, do not
seem to have in any way interfered with the grand scheme that was
involved. But it is very unlikely that elevation or subsidence either
was, or could be, universal at any given period; on the contrary, it
appears far more rational to suppose that every very extensive eleva-
tion was accompanied by a corresponding depression somewhere
else, and vice versa, and thus some sort of balance maintained. If
this is so, then we would naturally look in some distant quarter for
the counterpart of the effects which either elevation or subsidence *
may have produced in any one region of the globe. Seeing how
very general throughout the vast expanse of the Northern Hemi-
sphere are certain breaks in the geological series, are we not justi-
fied in looking to the region farther south for the evidences prov-
ing uninterrupted sedimentation and continuous organic evolu-
tion ?

If we attach full weight to the imperfection of the geological
record, it is not difficult to account for the apparent abrupt ap-
pearance of certain animal groups or faunas; indeed, the problem
would have been far more difficult to solve had the case been other-
wise. But there is one special instance of such appearance which
is not so readily accounted for, and which, under any hypothesis,
is almost inexplicable. We refer to the sudden appearance of the
numerous forms of life which characterise the oldest fossiliferous
formation with which we are at present acquainted, the Cambrian,

* Reference is here made to the more extensive movements of the crust,
producing the profounder breaks.

PALEONTOLOGICAL BREAKS. 195

when no unequivocal traces of preexisting life are anywhere to be
met with in the formation next preceding. So absolutely universal
is this condition that it almost staggers belief. It cannot rationally
be conceived that the varied Cambrian fauna could have come into
existence de se, without there being a line of progenitors to account
for its existence; but, if such progenitors did exist, which was
doubtless the case, what has become of their remains? Can it
be that all over the world, as far as we know, every fragment of
such a pre-Cambrian fauna should have been so completely wiped
out as to leave not a determinable vestige behind? It must be
confessed this seems very incredible, seeing with what absolute
perfection many of the oldest, and in many respects the most deli-
cate, structures have been preserved through all the vicissitudes of
geological time. The hexactinellid sponges of the Cambrian and
Silurian periods, the Silurian Foraminifera, and scarcely less so the
graptolites, bear ample testimony to a most astonishing power of re-
sistance. To account for such a wholesale obliteration, we must in-
voke the aid of a kind or degree of metamorphic action very different
from that which has since been made known to us, for it can scarcely
be supposed that the ordinary action extending back through only
one more period of geological time could have produced such pro-
found results. And it is not only from a comparatively brief period
of time that we must explain the utter absence of organic traces, but
from a period which, in the opinion of many geologists, may have
been of equal duration with the entire interval that has elapsed since
the deposition of the Cambrian sediments. But, even granting this
unknowable form of regional metamorphism, it still remains a mys-
tery how its effects could have been so universal as to wipe out
every vestige of an indisputable pre-Cambrian fauna. It is very
possible that the limestone of the Laurentian rocks owes its ex-
istence to organic agencies, and therefore represents in part this
earlier fauna; but even admitting this to be so, it helps the mat-
ter very little, since the limestone is overlaid by younger crystal-
line rocks, which are no less destitute of organic traces than the
deposits underlying it. For the same reason the existence or non-
existence, as an animal, of the much - debated Eozoon, does not
affect the point at issue; on the contrary, the total absence of de-
terminable organic traces, either above or below the Eozoon line,
would, in itself, apart from all other evidence, constitute strong

196 GEOLOGICAL DISTRIBUTION.

grounds for relegating that guasi-organism to the class of mineral
deposits. *

Darwin has sought to explain the anomaly on the supposition
that possibly the most ancient fossiliferous deposits lie buried deep
beneath the floor of our existing oceans, and that they may have
lain there ever since the Cambrian (Silurian) period. They would
then have been kept out of sight, and would, at the same time,
have offered no opportunities for their remains to become inter-
mingled with those of any subsequent formations. That there is
no insuperable objection to this explanation every one must admit,
and that it, at least, partially meets the case, is more than prob-
able. But it is still far from being in the nature of a demonstra-
tion. The doctrine of the permanency of land areas and oceanic
basins has much in its favour, and if true, would go far towards
supporting Darwin’s proposition; but, unfortunately, the absolute
proofs of such a condition are still wanting, and may forever re-
main wanting. The land surfaces from which the Paleozoic rocks
derived their sediments, cither in part or in whole, may or may not
have occupied the position of the present seas. If the former be the
case, the problem remains in its original form; if the latter, it must
be assumed that a broad hiatus exists between the Laurentian and
Cambrian series, and that the gap is filled by vast submarine de-
posits, upon which massive accumulations of continental and organic
débris have been superimposed. Fossils of a pre-Cambrian type may
be abundant in these deposits. Manifestly, however, the assump-
tion of large land areas depressed beneath the sea carries with it the
implication of an alternation of oceanic and continental surfaces,

* The question of the animal nature of Eozoon has been practically settled
in the negative through the researches of King, Rowney, Julien, and Mobius ;
the elaborate memoir on this subject by the last-mentioned scientist will proba-
bly be considered conclusive by most impartial zoologists. The present author
has himself examined masses of Eozoon rock in which the network of green
mineral, supposed to till the chamber-cavities of the giant foraminifer, coalesce
and merge into a broad band of serpentine. Now, either we have here a true
Eozoon structure or not. If yes, then on what zoological basis, it may be
asked, can the gradual convergence of the infiltrating mineral and its final
coalescence with a broad band of serpentine be explained? If the contrary,
what necessity is there for invoking the aid of organic forces in the explanation
of a structure, when one fully as intricate, and practically undistinguishable
from it, can be shown to be of purely mineral formation ?

EXTINCTION OF SPECIES. 197

and if this could have happened once, why may it not have occurred
again? Or might it be assumed that this, a primary oscillation,
first marked out the existing boundaries of land and sea? The
problem, in whichever light it may be viewed, is beset with in-
numerable difficulties, and, it must be confessed, lies beyond the
probability of a near solution. The evidence appears strong, how-
ever, for concluding that the Archean rocks, so recognised—d. e.,
those of the Laurentian and Huronian series—are by no means the
immediate predecessors of the Cambrian series. These may still
be found at some places underlying the last, or they may forever
remain hidden from view beneath the aqueous deep.
Extinction.—It has very generally been remarked that the ex-
tinction of species, or groups of species, appears to have been a
much more gradual process than their introduction. This is, doubt-
less, in great part true, and agrees well with the theory of natural
selection. The formation of a new species usually implies favour-
able conditions for the development of that species, and it is,
therefore, not surprising that when once formed the species should
spread very rapidly. When, however, through certain causes—
the alteration of the physical properties of the surroundings or
inferiority in the general struggle for existence — the conditions
for existence are no longer as favourable as they were before, we
should naturally expect to meet with a decline in the development
of that species, and its possible ultimate extinction. But unless
the change in the conditions of life were very abrupt, we should
nowhere look for immediate or sudden extermination. Every one
is familiar with what prodigious rapidity certain weeds, as the wild
carrot, for example, have spread in regions into which they had
but recently been introduced, but how very much slower has been
the extermination of the species of native plants which they may
have supplanted. The English sparrow has developed with sur-
prising rapidity in the Eastern United States, and, although since
the period of its introduction scarcely twenty years have elapsed, it
has so far multiplied and become master of the newly acquired
situation as to have practically appropriated for itself a large por-
tion of the domain formerly occupied by the native birds of the
same family, and to the exclusion of those birds. These, if they
eventually prove weaker in the race, may in course of time com-
pletely disappear, but, before that period will be reached, will

198 GEOLOGICAL DISTRIBUTION.

doubtless have effected a foothold in some neighbouring region,
and struggle on as best they can under what might be less favour-
able conditions for existence. Ultimately the race will be thinned
out and extinction of the species follow. A parallel case of sudden
appearance and much less sudden disappearance is afforded by the
two common species of house-rat, the black and the brown, both
of which, through introduction, have become more or less cos-
mopolitan in their range. Everywhere where the latter has suc-
ceeded in obtaining a foothold the former is gradually, but steadily,
fading away, relinquishing piece by piece the territory of which it
was at one time in full possession. But it still lingers on, and,
no doubt, will still continue to so linger for some time in the future,
a relic of a once formidable race. Yet its own march of conquest
was probably no less rapid than that of its more successful com-
petitor, the brown or Norway rat, which appears to have been
unknown west of the Volga River prior to about the middle of the
last century, and which has since spread so extensively as to render
it one of the commonest pests of both continental and insular
Europe. The species was first observed on the Pacific coast of the
United States subsequent to 1850, but it is scarcely less common at
the present time in California than anywhere else. The relation of
natural selection to extinction and persistence is clearly stated
by Darwin thus (‘‘ Origin of Species”) : ‘‘The competition will
generally be most severe, as formerly explained and illustrated by
examples, between the forms which are most like to each other in
all respects. Hence the improved and modified descendants of a
species will generally cause the extermination of the parent species;
and if many new forms have been developed from any one species,
the nearest allies of that species, ¢. e., the species of the same genus,
will be the most liable to extermination. Thus, as I believe, a
number of new species descended from one species, that is, a new
genus, comes to supplant an old genus belonging to the same
family. But it must often have happened that a new species be-
longing to some one group will have seized on the place occupied
by a species belonging to a distinct group, and thus cause its exter-
mination; and, 1f many allied forms be developed from the success-
ful intruder, many will have to yield their places, and it will gen-
erally be allied forms, which will suffer from some inherited inferi-
ority in common. But, whether it be species belonging to the same

EXTINCTION OF ANIMAL GROUPS. 199

or to a distinct class which yield their places to other species which
have been improved and modified, a few of the sufferers may often
long be preserved, from being fitted to some peculiar line of life, or
from inhabiting some distant or isolated station, where they have
escaped severe competition. For instance, some species of Trigonia,
a great genus of shells in the secondary formations, survive in the
Australian seas; and a few members of the great and almost extinct
group of ganoid fishes still inhabit our fresh waters. Therefore the
utter extinction of a group is generally, as we have seen, a slower
process than its production.”

There are instances, however, in which the extinction of certain
animal groups is generally considered to have been very sudden.
The trilobites and ammonites among invertebrates, and the dino-
saurian reptiles among vertebrates, may be taken in illustration of
such cases. But even here a careful examination of the premises
shows that the suddenness of extinction is probably much more
apparent than real, and that, as the facts now stand, they by no
means sustain the inferences that have been drawn from them, The
trilobites, for example, are frequently stated to stop suddenly at
the close of the Paleozoic era, whereas, as a matter of fact, no
trace of trilobites has ever been found in deposits unequivocally
newer than the Carboniferous. A whole period (Permian)—true,
a comparatively insignificant one—therefore, still intervenes be-
tween the extinction of the order and the close of the Paleozoic
era. But, again, even with the Carboniferous period the extinc-
tion is far from being sudden. Of the numerous genera which
so eminently characterise the Silurian fauna, only two genera,
Phillipsia and Proetus, both of them restricted to a comparative-
ly insignificant number of species, survive the Devonian period.*
These, together with two other genera now for the first time in-
troduced, Griffithides and Brachymetopus, constitute the entire
known Carboniferous trilobitic fauna; and of this limited number
only one genus, Phillipsia, and that apparently in America alone,
pisses up as high in the Carboniferous series as the Coal-Measures.
We thus see how very gradual, rather than abrupt, has been the final
—if final—extermination of this order of animals.

Nor do we have that sudden downfall, either in or from the

* Since the above was written, Professor Claypole has announced the dis-
covery of Dalmania in the Waverly Group (Lower Carboniferous) of Ohio.

200 GEOLOGICAL DISTRIBUTION.

Silurian period, which many authors are in the habit of insisting
upon. Thus, if we take the very elaborate tables of Mr. Etheridge”
as our guide, we find that the rise and fall of the British trilobitic
fauna has been, on the whole, gradual, the greatest break occurring
between the Llandeilo and Caradoc on the one side, and the Cara-
doc and Llandovery on the other, or along the horizon which, by
many geologists, is considered to mark a *‘ Middle” Silurian divi-
sion. The following scheme will exhibit the numerical, generic, and
specific values presented by the different horizons of the Paleozoic
series, from the base of the Silurian to the Carboniferous, inclusive:

FORMATIONS. Genera of Trilobites. Species.
ATOMIC sate sce atten eee 6 9
landedlor, 24 Pet eee eee Ae 18-20 45
ara oc isalay cc omer sate ere ces 27 123
Lower Llandovery............. 13 35 1 25
Upper Blandoverys e205 27", 24
enlocks,. 400% Oa BAT paw WsteN 23-95 (2)
mG Wee eee See Okeee 10 20
Devonian sete sels te cree tee ee 6 11
Carboniferous... .2 eee renee. 3 13

In the Bohemian basin, where the transition between the Cambrian
and Silurian faunas is very abrupt, the decline is, if anything, still
more gradual than in Great Britain. Barrande’s Etage C (Cam-
brian) holds, according to its illustrious monographer, 27 species of
trilobites; Etage D (base of Silurian), 118 species; E, 83; F, 88;
and G and H together, 66.*

In the case of the ammonites the disappearance is somewhat
more rapid than with the trilobites; but even here it is not nearly
so abrupt as it is very generally conceived to be. Thus, if we take

* J. Barrande, “ Trilobites,’? Prague, 1871. Of the 66 species contained
in faunas G and H, G alone possesses 64, and H only 2; it might, therefore,
be assumed that the extinction was here very rapid. But, as M. Barrande
himself informs us, the deposits of tage H are of insignificant development
when compared with either E, F, or G, and have, in fact, practically disap-
peared through erosion from the greater portion of the territory which they
formerly covered. ‘‘ Systéme Silurien,”’ i., 1851, p. 81.

EXTINCTION OF ANIMAL GROUPS. 201

the typical Cretaceous area of the peninsula of India as representing
a series of nearly continuous depositions from the Neocomian to the
Danian, inclusive, we find that there has been a very sudden dimi-
nution in the number of species before the top of the series is
reached. In the Lower Cretaceous division, the Utatur group, cor-
responding to the Cenomanian of continental geologists, the num-
ber of species of coiled Ammonites is, according to Stoliczka, 67;
in the middle division, Trichinopoly group (Turonian), 20; and in
the upper division, Arialur group (Sennonian), 21. In the upper-
most Arialur beds of Ninnyur, which probably correspond to the
“* Maestrichtian,” or Danian, not a single species is found. The
seeming anomaly that the upper and middle divisions of the Cre-
taceous (Arialur and Trichinopoly groups) should contain an equiva-
lent number of species is not exactly in harmony with the law of
gradual numeric diminution; but its explanation is, doubtless, found
in the fact that the development of the Arialur deposits is double
that of the underlying deposits of the Trichinopoly group.® In the
typical Cretaceous areas of England there is an equally well-marked
reduction in the number of species before the end of the series is
reached, and the same, although to a less extent, is also the case in
France. In California, where the breaks in the Cretaceous series
appear to have been of comparatively insignificant value, and where
a nearly continuous sedimentation tides over the gap which else-
where exists between the Cretaceous and the Tertiary, the disap-
pearance of the ammonitic fauna is a very gradual one. In the
lowest member of the system, the Shasta group, the coiled forms
number ten species; in the Chico group, six; and in the Martifiez
group, the top of the system, two. But, to draw out the line still
further, we have here the indisputable passage of one species into
the deposits of the Tejon group, the base of the Tertiary series
(Eocene). This unique case of an ammonite surviving the Me-
sozoic fauna, which will be, doubtless, repeated at many parts of
the earth’s surface not yet explored by the geologist, finds its paral-
lel in the similar survival in Australia of a solitary belemnite, if
the organism so described really proves to be such. Less grad-
ual in their disappearance, apparently, than the true ammonites,
are the uncoiled forms of the same family, whose remarkable de-
velopment, just before the close of the Mesozoic era, must be

considered one of the most striking facts in paleontology. But
10

202 GEOLOGICAL DISTRIBUTION.

here, as elsewhere, it should be remembered that the break almost
everywhere existing between the Tertiary and Cretaceous series of
deposits is a profound one, and covers not impossibly a lapse of
time fully equal to that which is measured by either of the two pe-
riods here mentioned, or even greater. It is, therefore, in no way
very surprising that a family still in its prime at the beginning, or
even near the end, of the Cretaceous period shouid have become
practically extinct before the beginning of the Tertiary, in the in-
terval between which there may have been, as Darwin characteris-
tically observes, ‘‘ much slow extermination.”

The doctrine advanced by many of the earlier geologists and
paleontologists, and still held by a few, that the duration of spe-
cies, or groups of species, is uniformly defined the world over by a
sharp and inflexible line, is, in the light of our present knowledge
of facts, untenable, and will not stand the barest test of logical
examination. It cannot fora moment be conceived that the con-
junction of the physical and vital forces should have so acted as to
simultaneously convert favourable into unfavourable conditions of
existence for the entire surface of the earth; as far as the widely-
distributed marine forms of life are concerned, nothing short of a
complete upheaval and laying dry of the sea-bottom could have
brought about such a condition, and, even granting such a consen-
taneous upheaval to have actually taken place, which probably no
geologist will for an instant admit, the overflow of the oceanic
waters would have afforded a safe harbour to many forms that might
have been displaced from their native habitat. Extermination or
extinction of the larger animal groups, especially if wide-spread,
will have been almost invariably preceded by displacement; unfa-
vourable conditions for existence, whichever way they may have been
brought about, will tend to promote migration, and, consequently,
when a certain group of animals becomes extinct at a given period
of time, at any one locality or region, we may confidently look for
its survival somewhere else, possibly in some very distant region.
Instances of such survival, in favoured localities, after the nearly
complete extermination of the race, we see in the Californian ammo-
nite and Australian belemnite already referred to, in the genera Tri-
gonia and Pholadomya among the acephalous mollusks, in the genus
Pentacrinus, and in Ceratodus, among fishes. The dinosaurian rep-
tiles, whose range in Europe only exceptionally extends to the top

AGE OF THE LARAMIE DEPOSITS. 203

of the Cretaceous series, the Maestrichtian,™ are carried in the West-
ern Territories of the United States to a horizon probably considera-
bly higher, the Laramie, whose position is now generally recognised
as Post-Cretaceous. Indeed, if the reported association in these beds
of one of the Hadrosauride with the remains of the mammalian Me-
niscoéssus be taken in its full value, we may not unreasonably as-
sume this fact to be further evidence, in addition to that which has
already been adduced, in favour cf uniting at least a portion of the
Laramie with the Eocene. Surely the circumstance that dinosau-
rian remains are found in these deposits is not of itself, as against
all other evidence, sufficient to establish the age of the formation.
Vi hat is there that we know of that should prevent the animals of
this group from continuing up into the Eocene, any more than the
Carboniferous and Permian labyrinthodonts into the Trias, and the
Cretaceous Crocodilia into the Tertiary? It is not to be supposed
that a common catastrophe awaited all the members of this numer-
ously-represented order of animals, when by their organisation they
seem to have been fitted to such varying conditions of environment.*

* Were these reptilian remains the only fossils of a distinctive character
found in the Laramie formation, then, naturally, we should conclude that the
formation in question was of Cretaceous age; at least, the only evidence we
had would be in favour of such a conclusion. But the case, as it here stands,
is quite different. The fossil plants of the Lignite, as is well known, are al-
most altogether of Tertiary types, and many of the species, even, have been
identified, by Starkie Gardner, Lesquereux, and others, with characteristic
Lower Tertiary forms occurring in various parts of Europe (Island of Sheppey,
&e.). The shell-fauna, as a whole, can scarcely be said to approximate very
much more to the one side than the other, although a few species have been recog-
nised by both Conrad and Meek as being more nearly Tertiary than Cretaceous.
These, however, do not indicate much. The recent discovery of Meniscoéssus
adds a much more powerful link to the evidence which favours the Tertiary side
of the question ; indeed, by itself it argues about as much for the Tertiary age of
the formation as the reptilian remains do for the Cretaceous, for, were there no
such conflicting testimony as in reality exists, its evidence would be accepted
as conclusive. Further evidence in this direction is afforded by the reptilian
genus Champsosaurus, which, as a member of a fauna, the Puerco, originally
supposed to represent the Laramie, has been identified as an Eocene genus in
the north of France. While, perbps, it may be admitted that paleontology has
not thus far given us absolute data by which to determine the question at issue,
yet, on the whole, its facts appear to lean more towards the Tertiary side. From
stratigraphy we learn but little, as, unfortunately, marine deposits of Post-Cre-
taceous age are wanting in the interior of the continent, thereby rendering the

204 GEOLOGICAL DISTRIBUTION.

Because they became extinct at a given period of time in one region
is no reason why they should have faded out during the same period
in every other; nothing could be more illogical than such an as-
sumption, and the facts, in numerous parallel cases, clearly demon-
strate its utter fallaciousness. Then why lay such stress upon the
occurrence of these animals as an indication absolute of geological
time ? Every day’s lesson teaches the geologist how unstable are the
limits that have been assigned by him to the duration of life in
species, or groups of species; it ought to be, therefore, a matter of
no surprise, but the reverse, to find certain so-called * distinctive ”
or ‘‘ characteristic ” forms becoming less and less distinctive with
the progress of investigation. The discovery of dinosaurian re-
mains in Tertiary deposits, or of trilobites in the Permian, should
give far less cause for surprise than a positive announcement that
they did nowhere so occur.

What the proximate cause of the extinction of species or groups
of species may have been, it is in most cases impossible to de-
termine. The process is such a gradual one, and its manifesta-
tion so casual, that we fail to see what it is just exactly that acts.
If, as Darwin puts it, ‘‘we ask ourselves why this or that spe-
cies is rare, we answer that something is unfavourable to its con-
ditions of life; but what that something is, we can hardly ever
tell. On the supposition of the fossil horse still existing as a rare
species, we might have felt certain, from the analogy of all other
mammals, even of the slow-oreeding elephant, and from the his-
tory of the naturalisation of the domestic horse in South America,
that under more favourable conditions it would in a very few years
have stocked the whole continent. But we could not have told
what the unfavourable conditions were which checked its increase,
whether some one or several contingencies, and at what period of
the horse’s life, and in what degree, they severally acted. If the

necessary correlation of strata impossible. At Laredo, on the Rio Grande,
Texas, the Claiborne beds (Parisian) are stated by Professor Cope to rest ‘‘im-
mediately on the Laramie” (‘‘ Proc. Am. Phil. Soe.,’’ 1884, p. 615). If this
is really the case. then it is more than likely that the latter is at least in part
the equivalent of the basal Tertiary, otherwise it would be difficult to account
for the sudden disappearance here of the vast thickness of sub-Claibornian
deposits (Buhrstone; Eo-Lignitic), measuring hundreds of feet, which else-
where along the Atlantic and Gulf borders forms the base of the Tertiary
series.

EXTINCTION OF ANIMAL GROUPS. 205

conditions had gone on, however slowly, becoming less and less
favourable, we assuredly should not have perceived the fact, yet
the fossil horse would certainly have become rarer and rarer, and
finally extinct; its place being seized on by some more successful
competitor.” The case of the horse here stated strikingly illus-
trates the mystery in which the subject of extinction is still involved,
and how very limited is our knowledge in this direction. Why
the animal should have become extinct on the American continent,
and at so early a period after its evolution, when under apparently
identical, or, at any rate, very similar, physical conditions, it con-
tinued to develop and thrive in the Eastern Hemisphere, is a prob-
lem towards the solution of which we can offer but vague conjecture.
Nor is the difficulty in the matter a whit lessened, but rather the
contrary, by the circumstance of the ready adaptability to its appa-
rently unfavourable environs which the more recently introduced,
or modern, horse has shown. Instances of this kind, anomalies
to our existing knowledge, are by no means rare. The extincticn
of the mammoth in the far north of the Eastern Hemisphere, and
the survival of its first cousin, the elephant, in the south, are equally
inexplicable. Both, as far as we are permitted to judge, appear to
have been in harmony with their surroundings; vegetable-feeders,
they inhabited regions of sufficiently luxurious vegetation, the one,
provided with a shaggy coat of hair to protect it from the rigours of
the frozen north, and the other, more nearly naked, suited to a
home where little or no protection from climatic extremes was neces-
sary. Both, again, were inhabitants of regions where a struggle
against the attacks of savage Carnivora was a part of their existence,
and if any advantage favoured the one side above the other in such
internecine warfare, it was on the side of the northern species. It
may just be, in the case of the mammoth, that the extreme cold
of the Glacial epoch, combined with a continuous submergence of
the land surface beneath an ice-cap, so far reduced the plant-
growth of the north as no longer to provide adequately for the
sustenance of these monsters, and that, as a consequence, they
gradually diminished in numbers, and eventually completely van-
ished. Such a supposition, however, must needs remain in the
nature of a mere hypothesis, until more facts than we now possess
shall have been gathered, indicating for it a high probability.
Similarly, the theory which accounts for the disappearance of the

206 GEOLOGICAL DISTRIBUTION.

mammoth on the supposition that it was swept off by unknowably
great glacial floods following in the wake of the northern ice-sheet,
has as yet little to support it. Why just the mammoth should
have been thus swept away, when other animals, like the reindeer,
contemporaries of the mammoth, and like it animals of the frozen
north, survived, is not very comprehensible.* The extinction of
the musk-ox in Europe and its survival in America offers a no less
remarkable puzzle to the biologist.

That very frequently what may appear to be insignificant causes
are sufficient to bring about extermination is shown in the case of
many of the largest, and seemingly most resisting, animals. The
arrested numerical development of the Indian elephant has been
attributed by Dr. Falconer, a competent authority, to the unceas-
ing harassings of insect pests, a view which was also shared by Bruce
with respect to the elephant of Abyssinia. And we are assured,
on the authority of Darwin, that ‘‘insects and blood-sucking bats
determine the existence of the larger naturalised quadrupeds in
several parts of South America.” The ravages of the tze-tze among
the South African ruminants has long been commented on by tray-
ellers, and the ‘‘ plague” of the mosquito is only too familiar to
require special consideration. Humboldt has graphically delineated
the numerous circumstances, including inundations, parched vege-
tation, ravages of wild beasts, and the like, which in many of the
grassy regions of South America threaten the destruction of both
cattle and horses, and these, or similar ones, exist over most parts
of the earth’s surface. In short, a perpetual check is placed upon
the free increase of all classes of organisms, the overcoming of
which displays the measure of success in the universal struggle for
existence. We know of no law which by itself determines the
duration of life in any group of organisms, or which explains why

* The mammeth, although its remains are most abundantly found in the
far north, cannot rightly be classed as an exclusively northern animal, as is
proved by the discovery of its bones in regions as far south as Santander, in
Spain, and Rome, in Italy. Indeed, it is not exactly impossible, as is claimed
by Boyd-Dawkins (‘‘ Early Man in Britain,’’ p. 108), that the modern In-
dian elephant is only a varietal form of this specics which, through long
habitation in the tropical or semi-tropical forests, has lost some of those minor
characteristics, such as the coating of hair or woo], which serve in a general
way to distinguish the northern animal. If this be true, then the mammoth
would still be a member of our existing fauna,

PERSISTENCE OF TYPE-STRUCTURE. 207

certain groups are much longer or shorter lived than others of a
very closely related nature.

Persistence of Type-Structure. — The persistence of certain
type-structures is very remarkable. Not only have they in a meas-
ure resisted all the modifying influences which Nature has brought
to bear upon them during a period of hundreds of thousands or
millions of years, but in such a manner as to render a specific sepa-
ration of their newest and oldest representatives a matter of con-
siderable difficulty. The Lingula of to-day differs but little from
the Lingula of the oldest fossiliferous formation with which we
are acquainted, the Cambrian, although the interval of time sepa-
rating the two has been variously put by geologists and physicists
at from one hundred to three hundred millions of years! The
pearly Nautilus is but little removed from some of its most ancient
representatives of the Silurian and Devonian seas, and, indeed, it
may be considered doubtful whether some of the existing Foram-
inifera are at all different from forms that occur deep down in
the Paleozoic series of deposits. The number of generic types that
have survived the Paleozoic era to the present day are sufficiently
numerous, but these belong as a rule to the lower classes of organ-
isms. Among the Brachiopoda we have at least five such genera
—Lingula, Discina, Crania, Rhynchonella, and Terebratula—and
two of these, Lingula and Discina, date back to the Cambrian
period. The Acephala and Gasteropoda furnish an equally large
number—Pecten, Mytilus, Nucula, Leda, Pinna, Lima, among the
former, and Pleurotomaria, Capulus, Turbo, Natica, Dentalium,
and Chiton, among the latter—and it is by no means improbable
that many of the older genera, now recognised as distinct by reason
of our imperfect knowledge concerning their true relationships,
have in reality representatives living in the modern seas. Of the
Paleozoic Cephalopoda we have but a single surviving genus, Nau-
tilus. Several of the recent genera of entomostracous Crustacea
(Estheria, Cypridina, Apus) range back in time to the Devonian or
Carboniferous periods, and a more limited number (Bairdia, Cythere)
even to the Silurian; but of the higher decapodous types we meet
with no (even doubtful) modern generic representatives until the
Carboniferous limestone is reached (Astacus Philippi, a supposed
species of crayfish, from the mountain limestone of Ireland). The
king-crab (Limulus), not unlikely a descendant from the more an-

208 GEOLOGICAL DISTRIBUTION.

cient line of Trilobites, appears for the first time in deposits of Ju-
rassic age. Contrary, perhaps, to what might have been expected,
following out the law of the persistence of lower over higher or-
ganic types, not one of the numerous genera of Paleozoic corals
has survived up to the present period; and what is still more sur-
prising, even the broad structural type which they embody has,
as far as we now know, almost completely disappeared. What par-
ticular conditions tended towards their extermination, and to their
being supplanted already in the early part of the Mesozoic era by
entirely new structural forms, we know not, and probably never
shall discover.

In sharp contrast to the more persistent types of animal life are
certain groups whose appearance and disappearance are alike sud-
den, and whose whole existence is measured by a very brief period
of geological time. Such, for example, are the Rudiste, a family
of acephalous mollusks which attains an extraordinary development
towards the close of the Mesozoic era, but all of whose members
appear to be restricted to the Middle and Upper Cretaceous periods.
Indeed, by far the greater number of representatives of this family,
constituting the genus (with several sub-genera) Hippurites, are
limited exclusively to the deposits of the Chalk and Chalk-marl.
An equally remarkable example of Hmitation in range is furnished
by the Graptolitidz, one of the most widely distributed families of
invertebrates with which we are acquainted, not a single undoubted
representative of which is known either before or after the Silurian
epoch.

It is a singular fact that etl of the more ancient terrestrial
air-breathing Mollusca that have thus far been discovered belong
not only to modern groups, but mainly, also, to modern genera.
Leaving out of consideration the more than doubtful Paleor-
bis, which by some is considered to be a land-snail, there have
been described, all in all, some seven or eight Paleozoic spe-
cies, beginning with the Middle or Upper Devonian, all of them
from the deposits of the North American continent. Three of these
have been referred to the genus Pupa, one to Zonites, and three
others to genera that have been created for them, respectively:
Dawsonella, Anthracopupa, and Strophites. The first of these is
not unlikely a true Helix, while the last, based upon a single im-
perfect specimen, is too ill-defined to permit of its being classed

PERMANENCE OF FRESH-WATER FAUNAS. 209

with certainty among the terrestrial pulmonates.*? It must be pre-
mised that these remains constitute only an infinitesimal fraction of
the entire pulmonate fauna of the period, and therefore it is impcos-
sible to say in what ratio the recent genezic types stand to types
that are not recent, but which may have lived and flourished and
left no traces of their existence behind them. The case as it
stands, however, is sufficiently interesting, and permits us to as-
sume that the process of modification among the land Mollusca
was an exceedingly slow one, probably very much slower than
among the corresponding marine forms of life. This seems also
to have been the rule with the fresh-water Mollusca, whose devel-
opment in time runs about parallel with that of the terrestrial
Pulmonata. It is now practically certain that the range of the ge-
nus Anodonta extends at least as far back as the Devonian period,
and not improbably the forms described as Naiadites, from the
Coal-Measures of Nova Scotia, are true Unios. No unequivocal
fresh-water Mollusca are as yet known from the Permian forma-
tions, and even in the Trias the number of such forms, doubtfully
referred to the genera Unio and Myacites, is very limited. Only
with the succeeding formation do we have the first considerable
development; but from that time onward to the present day the
number of species, in most cases referable to existing genera, rapidly
increases. The earliest fresh-water gasteropods date from the Juras-
sic period, and are comprised almost altogether in the modern genera
Neritina, Planorbis, Vivipara, Valvata, Hydrobia, and Melania. It
should here be observed that, while from the preceding data it may
appear that, with few exceptions, all the earlier (as well as later)
fluviatile mollusks, whether lamellibranchs or gasteropods, be-
longed to genera which still flourish in our fresh waters, this needs
not necessarily have been the case as a matter of fact; for many
forms that, by reason of their association with marine organic types,
have in themselves been classed as marine, may have been of a dis-
tinctly fresh-water habit. It is inconceivable that the only evidences
of life in the ancient waters of the land should be centered in the
few organic remains that we recognise to be of an indisputably
fresh-water character. Rivers, then as now, discharged into the
sea, and deposited large quantities of sediment along the conti-
nental borders. It could scarcely have happened otherwise than
that more or less perfect parts of shells, swept down by the currents,

210 GEOLOGICAL DISTRIBUTION,

should have accumulated in these river deposits in considerable
numbers; and, when once there, there is no reason for supposing
that their destruction would have been very much, if at all, more
rapid than in the case of marine shells. But, if none of the forms
that occur associated with distinctively marine types are in reality
of a fresh-water nature, what has become of these remains? Surely
it cannot be that they have suffered complete, or even nearly com-
plete, destruction. It seems far more reasonable to assume that
many of the forms described as marine, from indisputably oceanic
deposits, are in reality not such; and this may be the case not only
with such forms as, in their generic characters, are but barely dis-
tinguishable from known fresh-water types, but even with those
which have a strictly marine facies. For there can be little or no
question that the primitive fresh-water fauna was a derivative from
the marine; hence, the earliest fresh-water types must have been of
a structure but little different from that of their oceanic progeni-
tors, and barely, if at all, distinguishable by external characters
from them. From the first, however, they will have been subject-
ed to the modifying influences which result from a change in the
physical conditions of the environs, and which have wrought in the
course of ages (and rendered more or less permanent) those structu-
ral features which, at the present day, serve to distinguish the ma-
rine from the fluviatile type of organism.

If direct proof of the ready adaptability of marine or brackish-
water organisms to fresh-water conditions, or the reverse, were
needed, no more decisive testimony in this direction could be had
than is furnished by the ancient lake region of the Western United
States, which marks the position of the Laramie or Lignitic forma-
tion. The lacustrine deposits of this formation, which attain a
maximum development of some four thousand to five thousand feet,
have evidently been laid down in lake-basins formed through the
land-locking and slow desiccation of a continental arm of the sea,
which projected completely across the United States during the
Cretaceous period. The exclusively marine character of the organ-
isms which flourished at this time clearly indicate what was the
condition of the waters which they inhabited. Through a gradual
elevation of the land, which appears to have set in about the close
of the Cretaceous period, and the consequent formation of barriers,
the waters of this vast inland sea, by reason of their severance from

LARAMIE FAUNA. Qik

the oceanic basins, and the indraught of fresh water from its drain-
age area, progressively lost their salinity, becoming more and more
fresh with the advance of time. Many or most of the molluscan
types that flourished during the period of greatest salinity slowly
disappeared from the region— through extermination or migra-
tion—the result of an innate incompetence to adjust themselves
to the changing conditions of their surroundings. Others, more
fortunate, by slow degrees accommodated themselves to the newly-
imposed conditions, and found a congenial home in harmonic as-
sociation with such forms as the inflowing fresh water may have
thrown in with them, and which were in their way undergoing a
reversed modification. That this must have been the actual history
of at least a considerable part of the Laramie region there can be
no question, seeing what a remarkable commingling of fresh water
and marine, or brackish water, molluscan types is there exhibited.
Thus, we have frequent associations in the same stratum of the
genera Corbicula, Corbula, Unio, Neritina, Vivipara, and Gonioba-
sis, or Corbicula, Corbula, Ostrea, and Anomia, and, as Dr. White “
informs us, ‘‘the commingling of brackish- water [Ostrea, Ano-
mia, Corbula| and fresh-water forms occurs in some portions of the
Laramie deposits under such conditions as to compel the belief
that some of them at least lived and thrived together.” In further
association with these forms are representatives of the genera Leda,
Pectunculus, and Odontobasis, which, otherwise, are known only
from marine deposits.

It is true that, in the case of the Laramie fauna, we have no
evidence proving that any of its distinctive fluviatile types of or-
ganisms have been descended by modification from marine forms,
inasmuch as all of them may have been primarily introduced into
the sea by the inflowing streams. That this was the case with
many of the genera is indisputably shown by their great antiquity,
compared with that of the fauna of the Laramie leke-basin. But it
is by no means unreasonable to assume, sceing how very hetero-
geneous in its character was the fauna of the period, that, had the
freshening and desiccation of the primitive inland lakes been less
rapid, a complete transformation of marine into fresh-water types
with the retention of permanent characters, might have been
brought about. Such transformation appears to have taken place
in the case of a portion of the molluscan fauna of Lake Baikal,

212 GEOLOGICAL DISTRIBUTION.

and in that of two or three genera of mollusks recently described by
Smith and Bourguignat from Lake Tanganyika—Syrnolopsis, Lim-
notrochus, and Rumella—which have an undeniably marine facies.
But this adaptability of animals to what might be called oppo-
site conditions of existence is not confined exclusively to the class
of Mollusca; indeed, were this the case we should have but a small
fragment of our fresh-water fauna accounted for. The metamorpho-
sis of Branchipus into Artemia, and of Artemia into Branchipus,
is a well-known application of the law to the class of Crustacea.
The existence of seals in Lake Baikal, whose salinity is practically
nil, isa remarkable instance of much the same kind among the high-
est animals, the Mammalia, while as a noteworthy offset to this,
coming from very nearly the lowest of all organisms, is the occur-
rence of marine, or non-statoblastic, types of sponges (Lubomirskia)
in the same lake, as well as in the Upper Congo (Potamolepis).**
Variation in Persistent Types.—lIt is frequently asserted, even
by those who are considered competent of forming an opinion,
that the fact of our having in the existing faunas a number of very
ancient types is a proof positive against the validity of any slow
modification theory of descent. For, it is contended, we are here
brought face to face with certain structural types which have re-
sisted all sensible modification during a period of millions of years,
and have, consequently, baffled all evolutionary tendencies towards
reorganisation. Thus, we have, as has already been stated, the
Lingula of to-day practically identical with the oldest Lingula
known; the modern Nautilus, but little different from the Nautilus
of nearly the most ancient Paleozoic deposit, and the modern Pupa,
practically identical with the Pupa of the Carboniferous period.
A little reflection will show how illogical is the position which
is here assumed. That eertain species should have come down
to us with but slight modification from the earliest periods known
is about as much proof of non-modification in the group to which
they belong as would be furnished in the case of a house, where
the retention of the primitive type, the hut, might be taken in
evidence of non-modification in the whole class. If a want of
adaptation to the surroundings be the primary cause of variation,
then, manifestly, the rate of variation among the members of a
given group of animals cannot be a uniform one, for while some
of the members will be forced to extreme measures by reason of

VARIATION IN PERSISTENT TYPES. 213

their inability to cope with the less favourable conditions of ex-
istence to which, through one cause or another, they may be
subjected, others, under more favourable circumstances, and re-
quiring no adaptation to new conditions, will continue unchanged
as before. Hence, the same stock may continue in a direct line,
and yet, at the same time, throw off a number of side branches,
whose ulterior development may, or may not, keep pace with the
main stem. That the simple transformation of a group requires
either the immediate or the ultimate obliteration of that group,
has nothing to support it. Few naturalists at the present time
question the descent of at least some of the races of the domestic
dog from one or more species of wolf or jackal, yet these are living
side by side, and apparently without interfering with one another’s
wants. That a decadence in the one group or the other may ulti-
mately set in—in fact, has already set in—cannot be denied, but it
may be safely doubted whether, if it had not been for man’s inter-
vention, extermination of either the wolf or jackal would have
preceded that of the dog. <A struggle with competitors in a cer-
tain quarter of the globe, or the necessity of conforming to new
conditions of existence, may have developed specific characters in
some of the wolves which they had not hitherto possessed, and
which would not be necessary for more favoured forms occurring
elsewhere, or, possibly, living even in the same region. In the
same way that modification of the nautiloid type which, it is as-
sumed, has resulted in the formation of the genus Goniatites, does
not appear to have materially affected the parent stem, for we find
the genus Nautilus itself developing in almost equal abundance in
the periods succeeding the introduction of the goniatite as in those
preceding it. In the deposits of the Carboniferous formation,
which represent the period of maximum specific development in this
genus, we have, according to Zittel, eighty-four species represented ;
in the Trias about seventy, in the Jura fifty, and in the Cretaceous
deposits still sixty to seventy. The actual downfall begins only
with the Tertiary, where through the entire series there are but
fifteen known species. What should have brought about this sud-
den decadence it is, of course, impossible to determine. Cases of
undoubted transformism and extreme persistence like the one here
instanced are undeniably rare, but this seeming rarity is to be at-
tributed in great part to our ignorance respecting the genetic rela-

214 GEOLOGICAL DISTRIBUTION.

tionship which binds together the more ancient forms of life. The
Brachiopoda, however, offer partial examples of this kind, more
particularly the family Terebratulidz, and, where but a compara-
tively limited persistence is demanded, such instances are by no
means rare.

Geographical Distribution.—In comparing the past with the
present distribution of life upon the globe, one cannot fail to note
a well-marked difference. Broad distribution appears to have
been far more prevalent in the early period of the earth’s history
than now, and argues strongly for a predominance of more uni-
form conditions. Thus, if we take the class Brachiopoda by way
of illustration, we find that of some one hundred and thirty-five
recognised species and varieties living in our modern seas, there
is scarcely a single species which can be said to be strictly cosmo-
politan in its range, although not a few are very widely distrib-
uted, and, if we except boreal and hyperboreal forms, but a very
limited number whose range embraces opposite sides of the same
ocean. On the other hand, if we accept the data furnished by
Richthofen * concerning the Chinese fossil Brachiopoda, we find
that out of a total of thirteen Silurian and twenty-four Devonian
species, no less than ten of the former and sixteen of the latter
recur in the equivalent deposits of Western Europe; and, further,
that the Devonian species furnish eleven—or nearly fifty per cent. of
the entire number—which are cosmopolitan, or nearly so. Again,
of the twenty-five Carboniferous species North America holds fully
fifteen (or sixty per cent.), and a very nearly equal number are cos-
mopolitan. The evidence furnished by the fossils of the Arctic
regions is equally conclusive in this direction. Not only are the
vast majority of species of Paleozoic (Silurian and Carboniferous)
fossils of the far north identical with forms occurring in the de-
posits of both temperate North America and Europe, but many of
them are distinctive types of formations which have been recognised
in almost all parts of the earth’s surface where such formations have
been themselves identified. Thus, among the fossils obtained by
the officers of the late Polar expedition under command of Sir
George Nares, Mr. Etheridge ® has identified Atrypa reticularis (Si-
lurian) and Productus semi-reticulatus and P. costatus (Carbonifer-
ous), the first from Cape Hilgard, in nearly the eightieth parallel
of north latitude, and the last two from Fielden Isthmus, latitude

GEOGRAPHICAL DISTRIBUTION—PAST AND PRESENT. 215

82° 43’. These species, moreover, appear to have been just as
abundant in their respective positions north of the Arctic circle as
they were south of it. The coral fauna of the same region com-
prises, among other forms common to both Europe and North
America, such wide-spread species as Favosites Gothlandica and
Halysites catenulata, both from latitude 79° 45’ (Cape Frazer) ;
Lithostrotion junceum has been found as far north as latitude 82°
43’ (Fielden Isthmus).

Turning our attention to a somewhat antipodal portion of the
earth’s surface, Australia, we find that by far the greater number
of fossils that have been catalogued from its Paleozoic deposits are
species that were originally described from regions lying well with-
in the limits of the north Temperate Zone. In fact, the relationship
existing between this southern fauna and the faunas of Europe and
North America is so great as to practically amount to identity.
This correspondence is perhaps as well exhibited by the graptolites
as by any other group of animals, for we find that of the twenty-
four species recorded by Mr. Robert Etheridge, Jr., in his ‘‘ Cata-
logue of Australian Fossils” (1878), no less than eighteen are
species belonging to the United States and Canada. When we
seek to explain the broad distribution of life in the early periods of
the earth’s history compared to what it is at the present time, it
will naturally be concluded that greater facilities for dispersion, and
the prevalence of more equable conditions of climate, especially the
latter, were the prime factors involved in this distribution. If, as
may be contended, other conditions were also largely instrumental in
bringing about the general result, we are entirely ignorant of their
nature. That a different disposition of the land and water areas
than now obtains may have facilitated distribution in a manner
now no longer possible must be conceded, and there are abundant
proofs that considerable alterations of one kind or another, whether
in favour of, or against, dispersion, have at various times taken
place. But it is beyond question, as is shown by the distribution
of our existing marine fauna, that while the relations existing be-
tween land and water have much to do with distribution, yet the
determining factor in such distribution is after all the matter of

emperature, The comparatively limited north and south extent
of any fauna, even along a continuous coast line, contrasted with
its broad east and west range, sufficiently proves this to be the

216 GEOLOGICAL DISTRIBUTION.

case; and if further or more convincing proof were needed, we
have the fact, made pregnant by the recent deep-sea dredgings,
that many of the forms contributing to the surface faunas of the
north, and hitherto recognised as being essentially northern, are in
reality inhabitants of the southern zone as well, only that they here
constitute a part of the deep-sea (cold water) fauna instead of the
more superficial one. Naturalists have been in the habit of recog-
nising four or more distinct zoological provinces along either border
of the Atlantic, each one characterised by a more or less well-marked
assemblage of animal species; and about an equal number of such
provinces have been assigned to the Pacific littoral. In all these
provinces the admixture of forms belonging either north or south,
it must be admitted, is very great, so much so as to render the
drawing of a line of division a matter of the utmost difficulty;
nevertheless, taken in their entirety, the faunas are sufficiently dis-
tinct, and serve to mark the climatic influences which limit dis-
tribution. Of some five hundred and sixty-nine species of Mollusca
recognised by Fischer, in 1878, as occurring on the Atlantic shores
of France, no less than four hundred and twenty-seven, or seventy-
five per cent., also belong to the British coast, and about an equal
number to the Mediterranean.” On the other hand, of three
hundred and fifty-three species obtained by M‘Andrew from the
southern coast of the Iberian Peninsula, only fifty-one per cent.
were common to Britain, and a much smaller number, twenty-eight
per cent., to Norway.” The molluscan fauna of the Canary Isl-
ands numbers about three hundred species, of which sixty-three per
cent. belong to the coasts of Spain and the Mediterranean, thirty-
two per cent. to Britain, and seventeen per cent. to Norway. The
relation existing between northern and southern, or cold and warm
water, faunas is perhaps still better marked on the Western Atlantie
border. Thus, of a total of about three hundred species of mollusks
belonging to the ‘‘ Transatlantic Province ”—i. e., the eastern coast
of the United States included between Florida and Cape Cod—only
sixty recur north of the peninsula of Cape Cod. Again, of seventy-
nine species of shells collected by D’Orbigny from the coast of North-
ern Patagonia only twenty-seven were common to Uruguay and
Brazil. The rich mollusean fauna of the Japanese Archipelago, com-
prising four hundred and twenty-nine species, has only one hundred
and eighty-five representatives in the Chinese and Philippine waters,

GEOGRAPHICAL DISTRIBUTION—PAST AND PRESENT. 217

In sharp contrast to the limited faunas of a north-and-south
extension is the fauna of the Indo-Pacific region, whose domain
covers about forty-five degrees of latitude, mainly comprised within
the Tropical Zone, and extends over fully three-quarters of the cir-
cumference of the globe. The influence of an equable climate is
here plainly manifest. The molluscan species occurring in this tract
have evidently a very broad distribution, for we find that, out of
an estimated total of five or six thousand species, the Philippine
Islands alone possess twenty-five hundred species, and New Cale-
donia an equal number. Upwards of one hundred of the East
African species have been identified by Cuming in the faunas of
the Philippines and the coral seas of the Pacific, or over an ex-
panse of seventy to one hundred degrees of longitude, and Fischer
enumerates twenty-one species whose range takes up practically
every part of the province. On the other hand, only one hundred
and sixty-five species are known to connect this fauna with the
Japanese, although the two are separated from each other, in a
north and south line, by an interval of only ten to fifteen degrees of
latitude.

Facts such as have been here presented clearly demonstrate
how all-powerful in its influence upon distribution is temperature,
and warrant us in assuming that it was this agent, likewise, which
primarily controlled distribution in the past as well as in the pres-
ent. Were evidence of a nature other than that which is derived
from purely zoogeographical considerations needed to prove the
existence of more equable climatic conditions in the earlier periods
of the earth’s history, we have the testimony to this effect of the
ancient reef-building corals, whose remains are so abundantly im-
planted in the deposits of the temperate and frozen north, and, in
no less striking degree, ef the flora of the coal.

It is, however, a significant fact, that many parts of the oceanic
surface which may be said to enjoy practically identical climates
hold at the present day very dissimilar faunas (viewed from the
stand-point of species). Thus, of the four hundred or more spe-
cies of mollusks inhabiting the Japanese waters, it appears that not
more than twenty are found on the west coast of North America
(Oregon, California, Mexico). Nearly all the east-coast species of
the United States, south of Cape Cod, differ from the species of the
corresponding regions on the opposite side of the Atlantic, probably

218 GEOLOGICAL DISTRIBUTION.

not more than fifteen or twenty being common to Europe. Evi-
dently the oceanic abysses, with their deep layers of cold water,
constitute an almost insuperable barrier to the free migration of the
animals belonging to this class. It is a little remarkable that
no larger proportion (about fifty per cent.) of species should be
common to the European and American ‘“ Boreal” sub-regions.
The influence of land-barriers in shaping distribution is still more
marked than that of the sea. This is best seen in the case of the
Mediterranean and Red Sea molluscan faunas, where, of eight hun-
dred and eighteen species dredged by M‘Andrew in the Gulf of
Suez, only three were found to be identical with forms occurring in
the Mediterranean! For a long time it was supposed by naturalists
that not a single molluscan species occurring on the west coast of
the Isthmus of Panama reappeared on the Atlantic side, and, if it
is now known that this supposition was not absolutely in accord-
ance with the facts, it must be admitted that the number of recog-
nised transgressional forms, thirty-five out of five hundred to six
hundred,” is very insignificant. With the facts here stated before
us, it cannot be doubted that the broad dispersion of animal life
in past periods of the earth’s history was not only conditioned
by favourable climatic circumstances, but, in a marked degree, by
the absence of barriers to a free migration. That the amount of
land-surface permanently exposed during the Paleozoic era was
insignificant, in comparison with that exposed at the present day,
is strongly indicated by the vast extent covered by the more
ancient marine deposits, from which it would appear that the
seas were at that period practically continuous throughout their
broadest expanse. But this general supposition is based upon the
hypothesis of the permanence of continents and oceanic basins,
which, as has already been remarked, has much in its favour, but
is still far from being in the nature of a demonstration. Grant-
ing the probability of continental upheavals from the oceanic
abysses, then, naturally, must all conjectures regarding the rela- .
tionship between land- and water-surfaces, and the existence of
interposing barriers, be valueless. It may be hastily concluded
that the circumstance of very broad distribution is, in itself, strong
evidence tending to show that such continental elevations did not
take place, and that there was a true permanency in the position
occupied by the sca. This need not necessarily have been the

GEOGRAPHICAL DISTRIBUTION—PAST AND PRESENT. 219

case, however, for, with an equable temperature over the greater
part of the earth’s surface, it does not appear why species, or
groups of species, should not have readily found their way to
the most distant localities by simply following the line of coast.
The marine Antarctic fauna of the present time is more nearly re-
lated to the Arctic than to any other, and, if the species of the two
are almost altogether different, yet a large proportion of the generic
types, wanting in the intermediate region, are the same. Such are,
for example, the genera Trophon, Buccinum, Margarita, Astarte,
Admete, &c. A limited-number of the species, too, are identical
with species occurring in the waters of the north Temperate Zone.
There can be little doubt that the distribution of these forms to the
antipodal regions of the earth’s surface was effected by way of the
deeper zones of cold water, and there seems to be no necessity for
invoking the aid of a “spontaneous” Antarctic fauna to account
for the separation that exists between it and the Arctic. If this
explanation is the correct one, it is then a little surprising that we
do not meet, in the two regions, with a larger number of identical
forms; but it can readily be conceived that the necessary accom-
modation to new conditions of existence, imposed by pressure,
absence of light, and a different food-supply, may have brought
about, in the course of such a lengthy migration, variation in specific
characters, without sensibly interfering with the structural type of
the group.

If it now be assumed that, during the Paleozoic era, the broad
distribution of species was effected in pretty much the same manner
—i. e., by following the trough of the sea rather than the continental
border—we are at once confronted by the anomaly that the num-
ber of identical species occurring at the most widely separated
localities, instead of being very limited, is just the reverse. It is
true that, with a high temperature extending to the bottom of the
sea, specific modification resulting from a transference of abode
from the surface to the greater depths may have been less marked
than appears to be the case with a low temperature; but we have
no reason for supposing that any great variation in this respect
did exist, and almost certainly not enough to account for the dif-
ferences that present themselves. It would thus seem that the
broad distribution of former periods was effected principally along
predetermined coast-lines, One circumstance, however, which has

220 GEOLOGICAL DISTRIBUTION.

thus far received but little attention from physiographers, must not
be lost sight of in this connection, and that is, a difference in depth
of the oceanic abyss. On the theory of the permanency of oceanic
and continental areas, and the strong probability that the cceanic
basins really represent areas of subsidence, it may be confidently
assumed that the floor of the ocean has been pretty steadily subsid-
ing, from first to last; and, further, that the continental off-flow,
produced by the rise and development of the land-masses, will have
just as steadily tended to increase the depth of water in these basins.
At what rate this subsidence and gradual deepening may have taken
place it is impossible, in the present state of science, to determine,
and therefore we possess no means of ascertaining what might have
been the difference in depth for any two widely separated periods
of geological time. But it is by no means improbable that the
depth of sea during the greater part of the Paleozoic era was very
much less than it is at the present time; indeed, we are almost irre-
sistibly led to this conclusion by our knowledge that the water for-
merly occupied a much greater lateral extension, measured on our
present sphere, than it now does, and this, in addition, at a period
when the equatorial circumference of the globe was probably con-
siderably in excess of its present twenty-five thousand miles. With
only a moderately deep sea, the difficulty in accounting for a phe-
nomenally broad specific distribution is greatly lessened.*

When we seek to determine at what period the existing condi-
tions of distribution, or approximately such, were first introduced,
we find that it was not until the beginning of the Tertiary, although
the gradual modifications leading up to this change are clearly
traceable in the successive periods following the Paleozoic era. Of
some thirty-six species of fossils described by Coquand and Bayle
from the Jurassic deposits of Chili, South America, no less than
twenty, or more than one-half, are forms which are also found in
the equivalent deposits of Europe, and a fair proportion of these
have been identified at various points on the continent of Africa, in
the peninsula of India, the Himalayas, and elsewhere. The Jurassic
Cephalopoda of Kutch, India, comprise, according to Waagen,7? one

* Tt is true that, through terrestrial absorption, the oceanic mass is under-
going diminution in bulk; but it may be questioned whether the shallowing
produced thereby, since the beginning of the Paleozoic era, has very materially
affected the general depth of water.

GEOGRAPHICAL DISTRIBUTION—PAST AND PRESENT. 221

hundred and fifty-six species, of which number at least forty-seven
(or thirty per cent.), and probably considerably more, belong equal-
ly to the fauna of West Central Europe. Altogether, the Jurassic
faunas of the world, even those most widely separated, are most
intimately related to one another in both generic and specific charac-
ters. The same may be said, although to a less extent, of the faunas
of the Cretaceous period, many of whose most distinctive types,
especially of cephalopods an:l lamellibranchs, have a world-wide
distribution. The cephalopodous fauna of the Cretaceous deposits
of India, we are informed by Stoliczka,** holds, among its one hun-
dred and forty-eight species, at least thirty-eight that are common
in Europe (twenty-five and one-half per cent.), a high proportion,
but somewhat less than what we have seen obtains in the case of
the fauna of the period preceding, the Jurassic. Roemer" has de-
termined fourteen out of one hundred and twenty-eight species
(eleven per cent.) of fossils coming from Texas to be identical
with European forms, while Morton has recognised no less than
seventeen such from among one hundred Invertebrata belonging to
the State of New Jersey. This proportion has since been raised
by Credner.* The researches of D’Orbigny in South America,
of Coquand and Rolland in Africa, of Stoliczka and Waagen in
India, and of M‘Coy, Etheridge, and others in Australia, show
very clearly how far specific identity is carried over the earth’s sur-
face.

With the beginning of the Tertiary epoch (Eocene period) a new
era in zoogeography sets in. The broad dispersion of species has
become much more of a rarity than heretofore—indeed, an excep-
tion—so that the widely separated regions of the earth’s surface,
while they may yet be mutually related to one another in their
general faunal characters, are no longer bound together by that mul-
tiplicity of identical specific types which is distinctive of the earlier
periods. The conditions which prevail at the present day have
already become accentuated. This fact is clearly brought to light
by a study of the deposits occurring on opposite sides of the Atlan-
tic. Thus, it is doubtful whether, out of some four hundred to
five hundred species of mollusks belonging to the Eocene formation
of the Atlantic and Gulf borders of the United States, more than
twenty-five or thirty (six to eight per cent.) can be absolutely iden-
tified with forms occurring elsewhere. And yet we have seen that

222 GEOLOGICAL DISTRIBUTION.

the proportion among the Cretaceous species for the same region is
fully the equivalent of seventeen per cent. In the Miocene the
number of such equivalent forms appears to be still further lessened.
We find that among the Australian Tertiary Mollusca by far the
greater number of species are forms which have been for the first
time described from that region, although the European contingent
of the Cretaceous fauna is by no means an inconsiderable one.

Climatic Zones.—In a very ingenious paper on the Jurassic
fauna,”® Professor Neumayr, of Vienna, following the views that
had already been expressed by Trautschold and Marcou, has at-
tempted to show that climatic zones were already well differentiated
in the Jurassic period of geological time, and that homoiozoic belts,
corresponding to these, existed then pretty much as they do now.
Thus, on the Eurasiatic continent he recognises three distinct Jurassic
zones, a ‘‘ Boreal,” a ‘‘ Central European,” and a ‘‘ Mediterranean ”
—the first comprising the region of Northern and Central Russia,
from the Petchora to Moscow, and the deposits of Spitzbergen and
Greenland; the second, the region lying north of the Alps, with
France, England, Germany, and the Baltic provinces ; and the
third, the region of the Pyrenees, Alps, and Carpathians, with a
probable continuation in the Crimeo-Caucasian belt. The faunas
of these different regions are most intimately related to one an-
other, so much so that at first sight they would appear to form a
homogeneous whole. But Professor Neumayr has shown that, de-
spite this apparent homogeneousness, there are certain well-marked
differences which impress a distinct individuality on each of the
three. Thus, as one of the most distinctive biological characters
of the Mediterranean zone, we have the great development among
the Cephalopoda of the ammonitic forms belonging to the groups
(or genera) Lytoceras and Phylloceras, which are but feebly repre-
sented in the deposits of the Central European zone, and whose
substitutes there are the genera Oppelia and Aspidoceras, Both
these series of forms are wanting in the boreal zone, which also
lacks the coral-reef structures of the last. Inasmuch as the differ-
ences here noted occur in. regions which appear to have been in
open-water communication with each other, it is contended that
the absence from one fauna of the forms most distinctive of the
other could only have been conditioned by direct climatic in-
fluences.

ANCIENT CLIMATIC ZONES. 223

It is more than doubtful, however, whether the evidence that
we possess is sufficient to prove this position. Were the conditions
such as they are claimed, we should naturally look for some cor-
respondence between the disposition of the ancient isothermal belts
and the existing lines of latitude; but no such disposition ap-
pears to have obtained. Dr. Waagen, in his elavorate analysis of
the Jurassic cephalopod fauna of Kutch, India, unreservedly ad-
mits its much greater affinity with the equivalent fauna of the
Central European region than with the Mediterranean, although
geographically it is placed in much closer juxtaposition with the
former than with the latter. The genera Oppelia and Aspidoceras
are here both abundantly developed, and scarcely less so the genus
Phylloceras; Lytoceras, on the other hand, is restricted to two
species. The fact that Kutch is itself situated only twenty-three
degrees from the Equator, and fully twenty degrees to the south of
the northern limit of the Mediterranean zone in Europe, is scarcely
consistent with any theory upholding the zonal distribution of
oceanic temperature. Neumayr maintains that the elevated tem-
perature of the Mediterranean zone was induced by an equatorial
current possibly flowing from the southeast, or, at any rate, in open
communication with a sea in that quarter; but if this were so,
surely the same temperature (and not improbably a considerably
higher one) would have affected the Indian basin as well, whereas,
on the theory set forth, we have here evidence of just the opposite
character—z. e., of a lower temperature. Moreover, the evidence
obtained from the fossils of Australia and the east coast of Africa
seems to point to the conclusion, in the opinion of Dr. Waagen,”
that very probably ‘‘one large Indian Ocean existed during the
Jusassic period, of which only the very outskirts have been pre-
served up to this day in India, the east coast of Africa and the
west coast of Australia existing in nearly the same area as the In-
dian Ocean exists at the present time.” It can hardly be conceived
that colder currents flowing from the north should have so far
antagonised the influence of the more southerly heated waters as
to have brought about this singular discordance between the Euro-
pean and Asiatic faunas. And to make the problem still more
intricate, it would appear that a part of the Himalaya Jura, the
‘‘Spiti shale,” ‘‘from the prevalence of the genus Cosmoceras and
the large number of Aucelle,” really belongs to the boreal zone.

224 GEOLOGICAL DISTRIBUTION.

The assumption that because certain marine genera, of whose habits
we know nothing, are found in one region and not in another there
must of necessity be well-marked differences in the thermometric
conditions of the waters which they inhabit, is at best a precarious
one, inasmuch as it is founded almost exclusively on negative evi-
dence. This is clearly proved by the status of the Indian Jurassic
fauna, where, as we have already seen, one of the distinctive ‘‘ Medi-
terranean” genera of ammonites, Phylloceras, is abundantly inter-
mingled with those supposed to represent a more northern facies,
while the other, Lytoceras, is almost altogether absent. If it be
assumed that the presence of Aucelle in the Himalaya fauna suffi-
ciently demonstrates the cold-water facies of that fauna simply
because the genus is most abundantly developed in the northern
regions, Central and Northern Russia, Siberia, Spitzbergen, and
Greenland, why may it not just as well be assumed that the
northern fauna was of a warm-water facies, from the fact that the
same genus is abundantly represented in a region lying on the im-
mediate confines of the tropics? The great north and south range
of the genus Aucella, which is also found along the thirty-seventh
parallel of latitude in California (Cretaceous), far from proving the
existence of homoiozoic belts, indicates rather the contrary.

But very little dependence can be placed upon the genera of
Mollusca as indicating the thermal conditions of the waters which
they inhabited. There is at the present time on the east coast of
the United States, south of the forty-first parallel of latitude, only
one species for each of the three boreal, or Arctic (so recognised),
genera Astarte, Leda, and Nucula. Yet, during the Eocene and
Miocene periods, these same genera were abundantly developed in
the waters situated seven and ten degrees of latitude farther to the
south, and where, consequently, we might conceive a stratum of
cold water to have existed. But, unless certain astronomical or
physical conditions prevailed at the time with which we are not
acquainted, it is practically certain that the temperature of the water
was at least as high, if not higher, than it now is. Nor can it be
urged that in these Tertiary deposits we are dealing with a deep-sea
(cold water) fauna, or that a low temperature might have prevailed
simply as the result of the non-existence of a Gulf Strezm—a con-
tinuous sea separating the North and South American continents—
since we have just as conclusive testimony favouring the supposition

HOMOIOZOIC BELTS. 225

of an elevated temperature in the presence of such tropical or sub-
tropical genera as Voluta, Cypreea, and Oliva, whose remains occur
associated with the other genera already referred to, and whose
actual range extended at least as far north as at the present day,
and in the case of Voluta still farther.

The conclusions reached by European geologists as to the exist-
ence of two distinct belts or provinces in the Cretaceous area—a
Mediterranean and a Baltic—have also been applied by Roemer” to
the equivalent deposits occurring on the east and south American
borders. The New Jersey greensands (Sennonian), for example, are
petrographically and oryctographically correlated with the Upper
Cretaceous deposits of Northern Europe, and more particularly with
those of Northwest Germany, whereas the Texas basin is placed in
a similar relation with the ‘‘ Mediterranean” zone of Southern Eu-
rope. The much more southerly position of the American beds
relatively to the European is taken as conclusive evidence, not only
that the present climatic variation on the opposite sides of the At-
lantic, for the same parallels of latitude, had already then existed,
but also the existence of a well-defined northeasterly trending
current of warmer water, or Gulf Stream. That the New Jersey
Cretaceous fauna departs most widely from the Texan cannot be
denied; but the evidence is far from conclusive that this variation
is the result of direct climatic influences. At the present day the
fauna of the Gulf may be considered as a homogeneous whole, being
represented by much the same forms along its northern, western,
and southern contours. On the other hand, it differs almost wholly
from the fauna of the east Atlantic coast, although there can be but
little doubt that, were it not for the peninsula of Florida, a consid-
erable number of the forms now occurring exclusively on the east
coast would have found their way into the Gulf basin as well.
During the Cretaceous period the intermixture of east and south
coast species was very large, but, contrary to what might have been
expected, and directly opposed to Professor Roemer’s conclusions,
the Gulf fauna, or that corresponding to an enlargement of the
present Gulf area, appears to have been in itself of a very clearly
recognisable multiple character. From the list of Cretaceous fossils
of the United States, prepared by Mr. Meek, in 1864,"° it would seem
that, of some one hundred and sixty species belonging to the State

of New Jersey, no less than fifty, or nearly one-third, are also com-
11

226 GEOLOGICAL DISTRIBUTION.

mon to the Cretaceous area comprised within the States of Alabama
and Mississippi (forty-eight species to Alabama, twenty-seven to
Mississippi), lying some four hundred miles farther to the south,
and thus separated by an interval considerably exceeding that which
separates the Mediterranean and Baltic zones of the continent of
Europe. On the other hand, of about two hundred species cata-
logued as belonging to the State of Texas only some ten or twelve
are indicated as forming a part of the Mississippi and Alabama
faunas, although the last occupied a position but little removed,
either geographically or climatically, from the Texan. These facts
are hardly in consonance with the conclusions which have been
reached respecting the past distribution of climatic zones, and, if
broad differences do obtain between certain contiguous north and
south faunas, as is undoubtedly the case, their explanation must be
sought in causes other than those directly connected with clima-
tology. The nature of the sea-bottom, depth of water, &c., may
have had much to do in the matter.

Despite what may appear as overwhelming evidence, proving
exceptionally broad distribution in the past periods of the earth’s
history, even as late as the Jurassic and Cretaceous periods, Professor
Neumayr © and others have attempted to show that this condition
did not actually exist, at least as far as the Mesozoic era is concerned,
and that in reality specific cosmopolitanism is as well-pronounced at
the present time as it was formerly. Thus, it is contended that the
modern pelagic Mollusca, more particularly the Pteropoda, are of
exceedingly wide distribution, and that even among the Cephalo-
poda a considerable number of more or less cosmopolitan forms—
among them Argonauta Argo and A. hians—are to be met with.
Furthermore, it is urged that, if well-marked faunal variations are
manifested along the oceanic border, such variations do not obtain in
the oceanic abyss, where a uniform type dominates the faunal facies,
and with whose fauna many of the ancient life-series are to be com-
pared. The facts relating to the distribution of the Mollusca, mod-
ern and ancient, that have already been given, are sufficient to prove
the general erroneousness of the proposition here stated, and, if any
more proof in this direction were needed, none more significant
could be had than that drawn from the distribution of a member of
one of the very groups of animals cited by Neumayr, the Cephalo-
poda. The nautilus, which to-day appears to be restricted to the

SYNCHRONISM OF GEOLOGICAL FORMATIONS. 227

tropical seas, was, even as late as the Eocene period, found abun-
dantly as far north as the fortieth and fiftieth parallels of latitude.
That some of the ancient faunas may represent faunas of the deep
sea cannot be denied; but it appears far more probable, in the light
of recent investigation, that they are in the main of a littoral char-
acter. At any rate, that they are not comparable to the cold-water
fauna of the deep, which alone maintains somewhat of a uniform
character, is indisputably proved by the abundance of forms indi-
cating a high temperature. Furthermore, even the general identity
claimed by Sir Wyville Thomson for the abyssal fauna of the world
has quite recently been contested by the late Gwyn Jeffreys."

Synchronism of Geological Formations.—It is well known
that the order of deposit of the various formations, from the oldest
to the newest, is constant the world over, and that nowhere, except
where there may have been a reversal of the strata themselves, is
there evidence of a reversed position. Corresponding strata, as in-
dicated by the contained fossils, have, therefore, been considered
to belong to the same age, even though occurring in widely-sepa-
rated regions. This view, for a long time maintained undisturbed
by the earlier geologists and paleontologists, has been dissented
from by Edward Forbes, Huxley, and other advocates of the doc-
trine of faunal dispersion from localised areas or centres of distri-
bution (opponents of independent creation), on the obvious ground
that faunas, starting from a given point of origination, could only
spread by migration, and that such migration must consume time,
proportioned to the distance travelled and the physical and physio-
graphical facilities afforded for travelling. Hence, it was argued,
that widely-separated formations, showing an equivalent faunal
facies, as, for example, the Silurian of America and the Silurian of
Europe or Eastern Asia, or the Cretaceous of Europe and of South
America, could not be of identical age, and, probably, not even
approximately so. In support of this position, it has been urged
that during the present age of the world the faunas of the several
continents are widely distinct, and could, under geological condi-
tions, be considered as indicating different zoological (geological)
eras. In conformity with this view, Professor Huxley has pro-
posed ** the term ‘“‘homotoxis,” indicating similarity of arrange-
ment, in place of synchrony, to describe the relation of distant areas
of the same formation.

228 GEOLOGICAL DISTRIBUTION.

Pushing his conclusion to what appeared to be its furthest
legitimate point, Professor Huxley deduced therefrom two impor-
tant considerations: 1. That formations exhibiting the same faunal
facies may belong to two or more very distinct periods of the geo-
logical scale as now recognised; and, conversely, formations whose
faunal elements are quite distinct may be absolutely contemporane-
ous; ¢.g., ““For anything that geology or paleontology is able to
show to the contrary, a Devonian fauna and flora in the British
Islands may have been contemporaneous with Silurian life in North
America, and with a Carboniferous fauna and flora in Africa.” 2.
That, granting this disparity of age between closely-related faunas,
all evidence as to the uniformity of physical conditions over the
surface of the earth during the same geological period (é. e., the
periods of the geological scale), as would appear to be indicated by
the similarity of the fossil remains belonging to that period, falls
to the ground. ‘Geographical provinces and zones may have been
as distinctly marked in the Paleozoic epoch as at present, and those
seemingly sudden appearances of new genera and species, which
we ascribe to new creation, may be simple results of migration.”

These views are still held by a very large body of geologists.
But it can be readily shown by a logical deduction that at least one
of the conclusions arrived at (1) is, almost certainly, erroneous;
and that the second, based upon this one, derives no confirmation
from the supposed facts. If, as is contended, several distinct
faunas—i. e., faunas characteristic of distinct geological epochs—
may have existed contemporaneously, then evidences of inversion
in the order of deposit ought to be common, or, at any rate, they
ought to be indicated somewhere, since it can scarcely be conceived
that animals everywhere would have observed the same order or
direction in their migrations. Given the possible equivalence in
age, as is argued, of the Silurian fauna of North America with the
Devonian of the British Isles and the Carboniferous of Africa, or
any similar arrangement, why has it never happened that when
migration, necessitated by alterations in the physical conditions of
the environs, commenced, a fauna with an earlier facies has been
imposed upon a later one, as the Devonian of Britain upon the
Carboniferous of Africa, or the American Silurian upon the British
Devonian ? Or, for that matter, the American Silurian might have
just as well been made to succeed the African Carboniferous.

SYNCHRONISM OF GEOLOGICAL FORMATIONS. 229

Reference to the annexed diagram, where D represents a Devo-
nian area, say, in Europe, S a Silurian one in America, and C a
Carboniferous one in Africa—all contemporaneous—will render this
point more intelligible. Now, on the proposition above stated,
reasoning from our present knowledge of the antiquity of faunas,
and accepting the doctrine of migration, as maintained by Professor
Huxley and others, to account for the possible contemporaneity of

distinct faunas, it may be assumed that S (or America) will receive
its Devonian fauna from D ; D (Europe) its Carboniferous from C ;
and @ (Africa) a later fauna from some locality not here indicated.
In other words, migration, as indicated by the arrows, would set
in from D to 8; one from C to D; one from S to some possibly South
American Cambrian locality, and one, bringing a Permian or some
later-day fauna, from an unknown ‘locality towards C. Were this
order of migration to continue here, or at other portions of the
earth’s surface, in this or in a similarly consecutive manner, the
results obtained would be in perfect consonance with the facts pre-
sented by geology. But is there any reason whatever for the con-
tinuance of this order of migration? Surely no facts that have as
yet been brought to light argue in favour of a continued migration
in one direction. Why, then, it might justly be asked, could not
just as well a migration take place from S to D, and impose with
it a Silurian fauna upon a Devonian? What would there be to
hinder a migration from S to C, placing the American Silurian
fauna upon the Carboniferous of Africa? Why has it just so hap-
pened that a fauna characteristic of a given period has invariably

230 GEOLOGICAL DISTRIBUTION.

succeeded one which, when the two are in superposition, all over
the world (as far as we are aware) indicates precedence in creation
or origination, and never one that can be shown to be of a later
birth ? Surely these peculiar circumstances cannot be accounted
for on the doctrine of a fortuitous migration. And it certainly can-
not be supposed that, through a process of transmutation or develop-
ment, depending upon the evolutionary forces, a fauna with an
early-life facies will, in each case, at the point of its arrest have
assumed the character of the later-day fauna which belongs to that
position. Therefore, it appears inconceivable that a very great
period of time should have intervened between the deposition of the
fauna of one great geological epoch at one locality and that of the
same or similar fauna at another locality distantly removed from the
first. In other words, the migrations, for such must undoubtedly
have been the means of the distant propagation of identical or very
closely related life-forms (unless we admit the seemingly untenable
hypothesis that equivalent life-forms may have been very largely
developed from independent and very dissimilar lines of ancestry),
must have been much more rapidly performed than has generally
been admitted by naturalists. The facts of geology and paleontol-
ogy are decidedly antagonistic to any such broad contemporaneity
or non-contemporaneity as has been assumed by Professor Huxley;
and their careful consideration will probably cause geologists to
demur to the statement that “all competent authorities will prob-
ably assent to the proposition that physical geology does not enable
us in any way to reply to this question: Were the British Cretaceous
rocks deposited at the same time as those of India, or are they a
million of years younger or a million of years older ?”

But what applies to the broader divisions of the geological scale
also applies to the minor divisions. Thus, the subordinate groups
of a formation are almost as definitely marked off in the same order,
the world over, as are the formations themselves. After breaks in
formations the appearance of characteristic fossils is largely the
same, whereas, on the theory of synchronism of distinct faunas,
such a succession of forms would certainly not be constant. Taking
the facts in their entirety, the conclusion appears irresistible that
formations characterised by the same or very nearly related faunas,
in widely separated regions, belonged, in very moderate limits, to
approximately the same actual age, and were practically synchronous

SYNCHRONISM OF GEOLOGICAL FORMATIONS. 231

or contemporaneous. The singular uniformity in the lithological
character of many of the equivalent formations also favours this con-
clusion. It is true that a very limited number of cases are known, or
at least have been cited, where an old-type fauna is found interca-
lated with a fauna of newer date, reversing, as it were, the general
order of succession or deposition. Such are the ‘‘ colonies” which
M. Barrande has indicated as existing in the Silurian basin of Bo-
hemia, and which have been so forcibly dwelt upon by that investi-
gator as standing in opposition to any slow-modification theory of
descent and progression. Of a similar character are the colonies to
which attention has been called by Marcou; and the occurrence,
which has been observed in some parts of Scotland, of an Upper Si-
lurian fish-fauna in rocks of unquestionably Devonian age, may be
placed in the same category. It appears practically certain, however,
that in none of these cases is there a true reversion. In the Siluro-
Devonian faunal association of Scotland we have, doubtless, only one
of those common occurrences where the range of certain species of
animals has to be extended beyond what was supposed to be its far-
thest limit; for, as Mr. Geikie informs us, there can be no question
that the Silurian element was present in the seas immediately ad-
joining the Devonian basin during the period of the first deposition
of the Devonian rocks, and that it was subsequently admitted into
the last by the rupture of a separating barrier. The case of the Bo-
hemian colonies is, perhaps, not as readily explained; but, if they
exist at all, it is very likely that they represent a fraction of a fauna
which, through specially favourable conditions, has been permitted
to linger beyond the period marking the extinction of the fauna as a
whole, and which, through a short migration, has been transported
to its present quarters. It must be confessed, however, that our
knowledge respecting these colonies is very imperfect, and it is a
significant fact that their existence, in the sense which has been
preferred by their interpreter, M. Barrande, is completely denied
by Lapworth, Marr, and others.

In a recent address, delivered before the British Association for
the Advancement of Science (1884), Mr. Blanford has brought out
numerous facts tending to prove, in the language of the author,
‘“homotoxial perversity,” or the want of synchronic correspond-
ence existing between certain identical, or closely related, assem-
blages of fossil remains. It is shown, for example, that the famous

232 GEOLOGICAL DISTRIBUTION.

mammalian beds of Pikermi, Greece, with Hipparion, Dinotherium
giganteum, &c., which are generally classed by geologists as Mio-
cene, or Mio-Pliocene, actually overlie marine deposits of almost
unquestionably Pliocene age. In the Gondwana system of rocks of
the peninsula of India the Damuda group, whose flora is stated to
be more nearly allied to the Jurassic flora of Europe than to any
other, is overlaid by deposits holding an apparently Rhetic flora,
and these, again, are succeeded by beds whose faunal characters
partake of the Triassic period. The coal-bearing beds of Southern
and Eastern Australia are claimed by paleobotanists to be typically
Jurassic, while the interstratified marine beds, in the character of
their animal remains, are just as unequivocally Carboniferous. In
the Laramie formation of the Western Territories of the United
States we have a somewhat similar association of an Eocene Tertiary
flora, many of whose species are identical with forms occurring in
the Island of Sheppey, and elsewhere in Britain, with a vertebrate
fauna of a distinctively Cretaceous type.

That there should be no direct correspondence existing between
the chronological facies of the marine and terrestrial faunas and
floras is not very surprising, seeing that there exists no reason why
their special development should have covered equal periods of
time. Nor could it be rationally expected, in view of the variable
physical conditions prevailing over the land-surface, and the inter-
position of impassable water-barriers, that the development of a
land fauna or flora should, in itself, be equal for all parts of the
earth’s surface, even though these parts enjoy approximately the
same climatic influences. This negative condition is beautifully
exemplified in the utter dissimilarity of the modern mammalian
faunas of South America, Africa, and Australia, which, had we
known them in a fossil state, might have been taken to indicate
three very distinct periods of geological time, and the same might
have been said, in great measure, of their floras. Yet, were the
marine faunas belonging to these different regions examined, there
could be but little doubt as to their representing chronological
equivalents. It is, therefore, not very remarkable, and not specially
indicative of the existence of climatic zones, that the Australian
coal-flora should be of the type which is elsewhere represented in
the Jurassic deposits, and that it should be associated with a dis-
tinctively Carboniferous marine fauna. And no more remarkable is

SYNCHRONISM OF GEOLOGICAL FORMATIONS. 2393

the association in the Gondwana system of a Jurassic flora with a
Triassic fauna, or of a Tertiary flora and Cretaceous fauna in the
Laramie deposits of the United States. Less intelligible is the
reported superposition in the Gondwana rocks of a Rheetic flora
upon one of a Jurassic facies, and of a Triassic or Permian fauna
upon one of Jurassic age. As far as the faunal evidence is con-
cerned, both as relates to the ‘‘ Triassic” or ‘‘ Permian” and the
‘ Jurassic” types, it is so slender as to permit no safe conclusion
being based upon it. Thus, the only animals thus far recorded
from the Damuda (Jurassic) beds are an Estheria and two laby-
rinthodonts, one of which, Brachyops, is claimed to be allied to a
European genus from the Oolites. Equally unsatisfactory is the
Permian relationship that has been attached to the vertebrate fauna
of the overlying Panchet beds, which comprises three genera (four
species) of labyrinthodonts, whose nearest allies are found in the
European Trias, one species of dinosaur, and two dicynodonts,
believed to be nearly allied to forms described from what are now
recognised to be Permian rocks of the Ural Mountains. The very
limited number of species found in these deposits, together with
their uncertain relationship, is scarcely sufficient to identify a fauna,
and it must, therefore, be concluded that we are still far from
having evidence of a positive character proving an inversion in the
faunal series, or as indicating any important difference between
homotoxis and synchrony, where marine fossils are taken as the
determining guide.* The advantages possessed by these last over
others of a terrestrial nature for the purposes of geological classifi-
cation are obvious from their broad distribution and equal chrono-
logical development.

* Mr. Lydekker, discussing the remarkable labyrinthodont Gondwano-
saurus from the Bijori group, maintains that the balance of evidence is in
favour of regarding the Panchcet beds as of Triassic age ; the age of the Damuda
beds is left in doubt (Paleontologia Indica, 1885).

PACE Air.

GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

The present and past distribution of individual animal groups.—Foraminifera,
—Corals.—Brachiopoda.—Mollusca generally.—Crustacea.—Insecta.

FORAMINIFERA,

DesprIte the simplicity of their organisation, and their apparent
ready adaptability to the most varied phases of existence, it ap-
pears that the distribution of these animals is influenced, although
perhaps to a less degree, by much the same conditions which
govern the distribution of higher forms. While practically the
class is of world-wide distribution, and cosmopolitanism—at least
among groups of supra-specific value (genera, &c.)—the rule rather
than the exception, yet the influence of special conditions, as per-
taining to different sections of the earth’s surface, is markedly
manifest. Thus, we find that in the warmer regions of the globe
the foraminiferal fauna, as compared with the corresponding fauna
of the regions lying to the north and south, is very much richer
both as regards specific and individual development; and, further,
that it comprises a disproportionately large number of forms char-
acterised by unusual size ard structural complexity (Orbiculina,
Orbitolites, Cycloclypeus, Tinopora). Of some seventy or mcre
genera of Foraminifera calcarea recognised by Biitschli,®* thizty-
eight, or about one-half, are wanting in the Arctic seas, twenty-
five are wanting in the British and North seas, and fifteen in the
Mediterranean; on the other hand, all the Arctic and north tem-

DISTRIBUTION OF FORAMINIFERA. 235

perate genera are represented in the tropical and sub-tropical seas.
The number of generic forms thus made peculiar to the tropics is
about twelve. That all the northern genera should also be found
in the central waters is not specially surprising, seeing that the
same conditions of temperature which prevail over the one region
in the surface or shallow waters are met with in the other in the
deeper layers, or upon the oceanic floor. The numerical relation
existing between species and genera does not appear to vary accord-
ing to any known law of distribution. Many of the genera are
most abundantly represented in specific types in the tropics, while,
again, others attain their maximum development in the regions of
high latitude. Bitschli recognises ninety-nine species of Forami-
nifera calcarea from the Arctic province, one hundred and eighty-
five from the north temperate, and one hundred and ninety-eight
from the Mediterranean, an estimate which makes the Arctic prov-
ince slightly deficient as compared with either of the other provinces,
and the north temperate slightly in excess of the Mediterranean.
A more thorough investigation of the Mediterranean waters, how-
ever, will doubtless increase the number of forms occurring there
very considerably, seeing that upwards of one hundred and sixty
species have been found on the British coast alone. Despite the
seeming diversity given to the character of the Arctic foraminiferal
fauna by the ninety-nine or more* species occurring there, the
fauna is strictly a uniform one, the vast mass, about ninety-five per
cent., of its component material being made up of only a very
limited number of species—Globigerina bulloides, Cassidulina levi-
gata, C. crassa, Polystomella striatopunctata, &c.—a feature in a
measure also distinguishing the foraminiferal accumulation of the
deeper parts of the sea, the Globigerina ooze, in which the indi-
viduals of Globigerina, Pulvinulina, Orbulina, Spheroidina, and
Pullenia, especially of the former, preponderate to a very marked
degree. As in the case of other marine animal groups, the forami-
niferal fauna of the high north is most intimately related to its
antipodal fauna of the south. Of a total of fifty-three genera and
one hundred and eighty-nine species occurring in both the South-
ern (below the fiftieth parallel of latitude) and Arctic oceans, thirty-
two genera and sixty species are held in common by both areas; “

* Brady, in his report on the ‘‘ Challenger” expedition, recognises all in
all one hundred and eleven species.

236 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

eleven of the southern genera are wanting in the north, and ten of
the northern genera in the south.

The relation of the pelagic or surface fauna to that found in the
bottom deposits of the sea, which has given rise to much diversity
of opinion among naturalists, has had much light thrown upon it
by the recent deep-sea dredging expeditions. It appears now
practically certain that a vast majority, probably ninety-eight or
ninety-nine per cent., of known foraminiferal forms, including all
of the porcellanous and arenaceous groups, are permanent inhabit-
ants of the oceanic floor, being endowed with no swimming or
floating powers. The surface and mid-water forms are limited to
some eight or nine genera and twenty species,** many or most of
which (species of Globigerina, Orbulina, Spheroidina, Pullenia,
Pulvinulina) are identical with forms living in the lowest oceanic
layers and found in the Globigerina ooze, to the formation of which
they doubtless contribute very extensively through their prodigious
development.

In their importance as rock constituents, the Foraminifera stand
second to no other group of organisms; in their geological develop-
ment they are probably coeval with the entire period during which
the sedimentary deposits were being formed, although it is not
till beyond the middle of the Paleozoic series that their un-
equivocal remains are met with in any abundance. Barring the
much-disputed Eozoon, whose inorganie character may now be
accepted without much hesitation, the earliest indication that we
possess of this class of animals is in the Lower Silurian rocks, where
thus far but a single genus, Saccamina, has been positively deter-
mined. Two species of Lagena occur in the Upper Silurian of Eng-
land. There still exists too much uncertainty relative to the forms
known as Receptaculites, Ischadites, and their allies, to permit of
their being absolutely classed with the Foraminifera, and likewise
in the case of the various structures which have been referred by
Ehrenberg to the Silurian of Russia. This paucity in the Silurian
rocks, and not less so in the succeeding Devonian, and their com-
plete absence from the Cambrian, is not a little surprising, but may
perhaps be explained on the hypothesis that the earlier members
of the class were in the main devoid of tests, or of such parts as
could be readily preserved in a fossil state. The marked develop-
ment of the genus Fusulina in the Carboniferous rocks is one of

DISTRIBUTION OF FORAMINIFERA. 237%

the most striking of the faunal features of the period, and, aside
from the general importance attaching to the genus itself as a
rock-builder, acquires special significance from the circumstance of
the barrenness in foraminiferal remains of the formations immedi-
ately preceding. From the close of the Paleozoic period to the
present day there is a steadily increasing development of distinctive
types, and an equally steady approximation to the structural type
which dominates the modern seas. Almost every period is marked
by some extensive foraminiferal accumulation, and in nearly all
cases the distinguishing character is given to these accumulations
by genera which acquire successive importance. Such are the
Gyroporella limestones of the Triassic and Rhetic formations, the
miliolite and nummulitic rocks of the Eocene and Oligocene, and
the orbitoide rocks of the Oligocene and Miocene periods. In the
newer Tertiary deposits the representative genera are mainly identi-
cal with those inhabiting the modern seas, and even of the species
a fair proportion are identical. Of the most widely distributed
and most numerously represented modern genera the one which
has most thoroughly left its impress upon the rocks of past ages is
the genus Globigerina. Beginning in the Trias, it already attains
to considerable importance in the Rhetic, where, in association
with Textularia, Orbulina, and Quinqueloculina, it forms massive
limestones (Dachsteinkalk, near Hallstadt, in Salzburg). The chalk
is made up in large part of the three foraminiferal genera Glo-
bigerina, Textularia, and Rotalia, and the first of these, as has
already been seen, is the principal constituent also of the modern
Globigerina or Atlantic ooze.

Much diversity of opinion has existed among naturalists as to
the mutual relationship of these two classes of deposits—the chalk
and ooze. The general similarity of lithological character, height-
ened by a close identity existing between the contained faunas, has
led most scientists to believe that the present oceanic bottom is
but a continuation of the bottom of the Cretaceous seas—in other
words, that the Cretaceous epoch is continued up to the present
time without any very material change marking the progress of
organic life in the ocean’s deepest parts. The majority of the
foraminiferal types occurring in the one formation are represented
in the other, and the identity is carried even to a fair proportion of
the species. Further, Sir Wyville Thomson has shown that the

238 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

biological relationship is not restricted to the lower or microscopic
forms of life, but, on the contrary, manifests itself in almost as
marked a degree in some of the higher groups. Thus the sponges
of the Atlantic ooze appear to have been most closely related to
the ventriculite sponges of the Cretaceous period, and there is also
a predominance in both classes of deposits of the cidaroid type of
sea-urchin.

As opposed to the biological relationship, on the other hand, it
has been pointed out that the physical constitution of the two
classes of deposits is very different. Thus, while Cretaceous chalk
almost invariably contains from ninety-four to ninety-nine per cent.
of carbonate of lime, and, consequently, at the utmost only about
six per cent. of foreign substances, analyses of Globigerina ooze
show it to contain only from forty-nine to eighty per cent., allow-
ing a very considerable percentage for impurities. Such a differ-
ence in chemical composition is certainly very striking, the more
especially as the composition of true chalk is very constant, and
appears to point to a mode of formation different in the two
cases. The correspondence in chemical composition existing be-
tween true chalk and the Oahu chalk (coral débris) of the Sand-
wich Islands has suggested to Mr. Wallace the notion that not
improbably both deposits have much the same formation—in other
words, that the chalk was deposited in a comparatively shallow
sea, probably not exceeding one thousand fathoms in depth, in
which numerous islands were scattered about in a manner somewhat
similar to what is observed in the coralline zones of the Pacific Ocean.
It has been further urged, in support of this view, that in the
opinion of many conchologists, notably, Mr. Gwyn Jeffreys, all, or
nearly all, the Mollusca of the Cretaceous sea represent comparatively
shallow-water forms, there being a total absence of such shells as
could with positiveness be considered as pointing to a deep-sea
habitat. Numerous objections, however, interpose themselves to
the views so ingeniously framed by Mr. Wallace. In the first place,
it would be purely gratuitous to assume that a comparatively shal-
low coralline sea extended into a continental area whose expanse
equalled the tract covered by the chalk deposits of Eurasia; sec-
ondly, had such a sea existed we should naturally expect to find,
as has been urged by Mr. Starkie Gardner, the remnants of ancient
coral reefs, such as are at the present day being formed in the

DISTRIBUTION OF FORAMINIFERA. 239

Atlantic, Pacific, and Indian oceans, but, singularly enough, no
such reefs have thus far been detected in the deposits in question;
indeed, even the scattered coral fragments are in themselves re-
markably scanty, and far from sufficient to give a coralline aspect to
the formation; thirdly, while many of the chalk Mollusca may appear
to represent shallow-water forms, there are yet a number, includ-
ing some of the most characteristic forms, concerning whose habit
nothing positive can be stated, since not only have many of them
no living representatives in the faunas of the present seas, but even
the families to which they belonged have completely died out.
While possibly, then, we may not have as yet arrived at an exact
comprehension of the nature of chalk, it must be confessed that
the biological facts already indicated point to a very close rela-
tionship with the Globigerina ooze. Nor is it at all unlikely that
the difference existing in chemical composition is one more appar-
ent than real. Thus, the deficiency of silica—and, consequently,
the surplus of carbonate of lime—in chalk can be readily accounted
for on the supposition that the free silica originally present in the
Cretaceous seas may have sifted itself during the formation of the
chalk into those irregular nodules which we now recognise as flints,
and likewise into the irregular fissures in the chalk, to form the
chalk-veins. Again, it may be assumed that chalk, during the
long lapse of ages that has intervened since the period of its forma-
tion, may have through various causes undergone considerable
alteration in its chemical composition, and sufficient to account for
the dissimilarity existing between it and the Globigerina ooze.
Perhaps the most remarkable feature connected with the history
of the Foraminifera is the long period of time through which pri-
mary characters have been retained; persistence of type-structure
is, indeed, immeasurably better marked in this group of organisms
than in any other. It is true that the views of naturalists are very
much at variance as to the proper limitations to be assigned to the
beings composing this most difficult group of the Invertebrata, and
that some of the most eminent authorities are disposed to unite the
greater number of both recent and fossil forms into a comparatively
limited number of diverging or central types; but, even from the
more conservative standpoint, enough is patent to indicate a most
extraordinary specific longevity. This is most clearly brought out
by the data furnished in Mr. Brady’s report on the ‘‘ Challenger”

240 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Foraminifera, whence it would appear that, of some seven hundred
recognised species, the range of not less than three hundred and
thirty-eight extends as far back as the Tertiary period; of one hun-
dred and twelve to the Cretaceous; fifty-six to the Oolite; forty-one
to the Lias; sixteen to the Trias; eight to the Permian; six to the
Carboniferous (Haplophragmium agglutinans, Ammodiscus incer-
tus, A. gordialis, Truncatulina lodatula, and the two Silurian forms) ;
two to the Devonian (also Silurian); and two to the Upper Silurian
(Lagena levis and L. suleata). A number of other doubtful forms
occurring fossil may perhaps also be referred to the category of
recent equivalents, as, for example, the Girvanella, described by
Nicholson and Etheridge from the English Silurian deposits, which
not improbably is the recent Hyperamina vagans.

CORALS.

The more important corals of the present day belong to the
groups Zoantharia and Alcyonaria, the former of which, frequently
designated the six-tentacled corals (Hexacoralla), embrace the naked
sea-anemones (Actiniz), and nearly all the familiar stone-corals, and
the latter (Octocoralla, eight-tentacled corals), the sea-pens, sea-
shrubs, red-coral, and organ-pipe. In the group of the comb-
bearers (Ctenophora) are comprised a limited number of forms,
Beroé, Venus’s girdle, &c., which are entirely destitute of a coral-
lum, and in many essential points of structure depart widely from
the other members of the class. A fourth division, the rugose
corals (Rugosa or Tetracoralla), which, in the early periods of the
earth’s history, constituted such a marked feature in the successive
faunas (Silurian, Devonian, Carboniferous), are limited at the pres-
ent day, as far as our existing knowledge goes, to possibly not more
than two generic types, Guynia, from the Mediterranean and the
Gulf of Mexico, and Haplophyllia, from the coast of Florida.

The sea-anemones are, collectively, cosmopolitan in their distri-
bution, and inhabit the sea to very nearly the profoundest depths
that have thus far been reached by the dredge, although, both as
regards specific and numerical development, they more distinctively
characterise the littoral and laminarian zones. The deep-sea species
are, however, not exactly scarce, and it would appear, from the
‘*Challenger ” observations, that the numerical decrease corre-
sponding to the increase in depth is not nearly as great as might

DISTRIBUTION OF CORALS. 241

have been expected. In ninety-seven hauls, made in depths ranging
from ten to five hundred fathoms, positive results, with a capture
of some twenty specimens, belonging to thirteen or more species,
were obtained eleven times; in one hundred and sixty-five hauls,
made in water of from five hundred to twenty-nine hundred fath-
oms, similar results, with a capture of sixty specimens, representing
twenty-one species, were obtained fourteen times. In the deeper
dredgings, however, the casting of the net was protracted over a
greater period of time, and, consequently, covered more space than
in the shallower ones, and due allowance should be made for this
circumstance. The relative abundance of the deep-sea Actiniz is
shown by the fact that not infrequently two or more species, or in-
dividuals belonging to a single species, are found associated in the
same locality. The greatest depth from which any species has thus
far been obtained is twenty-nine hundred fathoms (Antheomorphe
elegans).

Professor Hertwig, from the data collected by the “ Challenger,”
believes it may be safely assumed that, the greater the depth of
water the greater is the variation between the deep-sea forms and
those of the coast-line. Thus, it is shown that, of the thirteen spe-
cies and twelve genera obtained from a zone of ten to five hundred
fathoms, only five species and two genera were found to be new, or
as not essentially belonging to the coast; on the other hand, of the
twenty-one species and seventeen genera obtained from a depth
of from five hundred to twenty-nine hundred fathoms, eleven of the
genera, and, with one exception, all of the species, were new.** The
same authority finds that increased depth exerts a remarkable influ-
ence in modifying the organisation of many of the forms. Thus,
the tentacles exhibit a distinct retrograde formation, or degenera-
tion, being first transformed into tubes, and ultimately into simple
openings in the oral disk. ‘‘In Paractis tubulifera (depth eighteen
hundred and seventy-five fathoms) the tentacles have the same con-
stitution as in the majority of Actinie, except in one point, that the
terminal opening, which is usually small or entirely wanting, gapes
widely. In Polysiphonia tuberosa (five hundred and _ sixty-five
fathoms) the tentacles have become short, slightly movable, wide-
mouthed tubes; in Sicyonis crassa (sixteen hundred fathoms) they
are small, wart-like rings, and in Polystomidium patens (eighteen
hundred and twenty-five fathoms) and Polyopis striata (twenty-one

242 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

hundred and sixty fathoms) the walls have almost entirely disap-
peared, so that the terminal opening forms a fissure in the oral disk,
the last remains of the tentacle being represented by a circular
margin surrounding the fissure, and so we come finally to the genus
Liponema (eighteen hundred and seventy-five fathoms), in which
the points at which the tentacles were actually placed are merely
indicated by openings in the oral disk.” The very limited number
of specimens obtained by the expedition prevents any definite con-
clusions being arrived at as to the horizontal distribution of the in-
dividual species. The majority of the forms, as Anemone, Actinia,
Metridium, &c., inhabit a superficial zone, especially the rock-pools,
situated at about low-water mark, where they attach themselves to
some foreign body by means of their muscular pedal-disks; others,
like Peachia, Edwardsia, Cerianthus, and Halcampa, lie more or
less buried in the sand, while a very limited number are free-swim-
ming or pelagic (Arachnactis). No fossil remains indisputably
belonging to this group have as yet been discovered.

Much the larger number of coral-depositing zoophytes of mod-
ern seas belong to the group of the Madreporaria, or, as they are
frequently termed, from their dermal corallum, the Zoantharia
sclerodermata, as distinguished from those which, like the ‘‘ black
corals” (Antipathide), secrete an internal corallum or basal skele-
ton (Zoantharia sclerobasica). Two divisions of these corals may
be conveniently recognised, the “solitary” (whether simple or
compound) and the ‘“ massive,” or reef-building corals, the former
of which are essentially deep-sea forms, rarely coming within the
littoral zone, while the latter are just as distinctively shallow-water
forms, extending from low-water line to twenty or twenty-five
fathoms.

The deep-sea corals are spread throughout nearly the whole of
the oceanic expanse, from the confines of the frozen sea on the
north to the Antarctic barrier on the south, and from very nearly
the surface of the water to depths of at least twenty-nine hundred
fathoms. The distribution of the individual species appears to be
largely, if not almost altogether, independent of considerations
connected with temperature. Sars obtained Fungiacyathus fragilis,
a member of the family Turbinolide, off the Loffoden islands, from
a depth of three hundred fathoms. Bathyactis symmetrica, appar-
ently the most widely distributed of all known corals, has been

DISTRIBUTION OF CORALS. 243

dredged off the Bermuda islands in thirty fathoms of water; off the
Virgin islands in three hundred and ninety fathoms; off Martha’s
Vineyard in two hundred and fifty; and off the coast of Japan
in twenty-nine hundred. Deltocyathus Italicus has been obtained
off the Bermuda islands from depths of two hundred and ten
hundred and seventy-five fathoms, respectively; off the West In-
dies from a depth of seventy-five fathoms; off the coast of Cape
Cod from one hundred and forty-two; and in the South Pacific
(latitude 32° 36’, longitude 137° 43’ west) from a depth of twenty-
three hundred and seventy-five. The total number of genera
which have been found at depths exceeding fifty fathoms is,
according to Mosely,®’ forty-eight. Of these, only five—Caryo-
phyllia, Deltocyathus, Flabellum, Bathyactis, and Leptopenus—
reach or pass beyond the fifteen hundred fathom line; the last has
thus far been obtained only in water exceeding fifteen hundred
fathoms, whereas the other genera range to within fifty or one hun-
dred and fifty fathoms of the surface. By far the greater number
of the genera range to within the fifty to one hundred fathom line,
and a limited number (Caryophyllia, Paracyathus, Flabellum, Bala-
nophyllia, Dendrophyllia, &c.) into still shallower water. Most of
the species have a very broad horizontal distribution, and a fair
proportion of them approach cosmopolitanism. The range of Ba-
thyactis symmetrica, above noted, is practically world-wide, indi-
viduals of the species having been obtained from the Azores, the
Massachusetts coast, the Bermudas, the east and west coasts of
South America, Kerguelen Island, the coast of Australia, the Mo-
lucca seas, and the coast of Japan. Scarcely less extensive is the
range of Deltocyathus Italicus. Caryophyllia communis has been
taken off Nova Scotia, the Azores, the Bermudas, and the Cape of
Good Hope. The only genera which appear to be restricted in
range are Stephanophyllia and Sphenotrochus, which as yet have
been obtained only from the shallow seas of the Malay Archipelago.
The compound Madreporaria of the deep-sea are very limited, both
specifically and individually, the most abundant form dredged by
the “ Challenger” being a species of Lophohelia (L. prolifera).

In their relations with fossil forms the deep-sea corals have re-
vealed very little of special importance. Somewhat more than one-
third of the genera are represented in the Tertiary formations, and
a considerably smaller number (Caryophyllia, Trochocyathus, The-

944 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

cocyathus, Parasmilia, Lophohelia, &c.) in the Mesozoic series. No
Paleozoic genera are represented, and, if we except the Cyathon-
axide, apparently not even any of the distinctive families. A few
of the forms have been identified with Tertiary species, as Delto-
cyathus Italicus, Caryophyllia communis (Sicily), and, among others,
possibly one or more species of Flabellum and Stephanophyliia.
Caryophyllia cylindracea, a well-known European Cretaceous spe-
cies, has been dredged in eleven hundred fathoms water off the
coast of Portugal, in associations with other forms of an equally
ancient aspect.®® One species of Stephanophyillia (S. complicata,
from the Ki Islands), although having its nearest ally in the 8. dis-
coides from the London Clay (Eocene), is, remarkably enough, in
certain peculiarities of structure, most intimately related to a form
from the Jurassic formation of Germany (S. florealis). At the pres-
ent day, as far as is known, the genus survives only in a remote
spot of the East Indies, completely severed from its former Euro-
pean habitat. Desmophyllum ingens, from the fjords of Western
Patagonia, appears to be specifically identical with an undetermined
species from the Quaternary deposits of Messina, Sicily.

It will be manifest, from what has preceded, that the modern
distribution of the deep-sea corals affords little satisfactory evidence
as to the special conditions—light, temperature, or depth—which
affect the development of this class of animals. Indeed, it would
appear at first sight as though none of these conditions were di-
rectly involved in the distribution of the group as a whole, or of its
individual members. The great bathymetrical range of many, or
the majority, of the forms, from the surface waters of a mild tem-
perature to the water of icy coldness, clearly proves the ready adapt-
ability of these organisms to extremes of temperature, or, what
might also be true, the want of appreciation, on their part, of ther-
mometric conditions. It is to be noted as a remarkable circumstance
in this connection, seeing through what an extensive range of tem-
perature their vertical distribution extends, that so few of the forms
penetrate within shallow water, or water of less than fifty fathoms.
Professor Fuchs has attempted to explain this anomaly on the as-
sumption that these, as well as other strictly deep-sea organisms,
were animals of darkness, and that they rarely penetrated within
the zone of light-penetration. But it may be questioned, as has
already been done when treating of the life of the sea, whether the

DISTRIBUTION OF CORALS. 245

interpretation here given of the abyssal fauna is a valid one. In-
deed, it might be doubted altogether whether there is such a thing
as a true fauna of darkness; or, if existing, it may be considered
questionable whether the members composing it have not become
habituated to present conditions through force of accident or a
process of degeneration, rather than through selection as guided by
individual instinct or volition. It appears highly improbable on its
face that animals so feebly endowed with perceptive powers as
these appear to be, and which at the same time possess a most
extraordinary adaptability to extreme conditions of temperature and
pressure, should be so constituted in their relations to illumination
as not to be able to endure the quantum of light which passes
through even the shallowest stratum of water.

The present broad distribution of the deep-sea Madreporaria
appears, likewise, to have obtained in the earlier geological periods.
Thus, Professor Duncan has shown, from his researches on the fossil
coral fauna of the West India islands, that a number of the forms
occurring there, in both the Eocene and Miocene formations, are
such as had been already previously described from the equivalent
deposits of Europe, e. g., Paracyathus crassus, Trochocyathus cor-
nucopie, T. laterospinosus, Ceratotrochus duodecimcostatus, the last
three from Italy, and the second also from the Vienna basin. Fla-
bellum appendiculatum, from the Oligocene beds of the island of
St. Bartholomew, is a species from Biarritz and Ronca; Trocho-
smilia subcurvata, from the same island, occurs in the Eocene beds
of Oberburg, in Styria, and T. arguta, at Castel Gomberto, in
Venetia, and other Oligocene localities.*® Other Tertiary species
have since been identified as being trans-Atlantic, and, doubtless,
many forms will be found whose range is still very much greater.
The Italian Conotrochus typus, Balanophyllia cylindrica, and Delto-
cyathus Italicus, are found also in the Australian Tertiary strata.°°
In view of the very extended range of so many of the species, the
distinctness of the Indian (Sindh) coral fauna, which holds scarcely
any species in common with any distant region, at least as far as
has yet been determined, is not a little remarkable. Considering
the apparent independence of the animals of this class, of the vary-
ing conditions of temperature and pressure which a habitation of
the deep-sea presents, and not unlikely also of other physical
conditions as well, it is difficult to account for the comparatively

246 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION,

short range in time of the different species end genera. It is in-
deed true, as far as the genera are concerned, that the very limited
number of areas of deep-sea deposits may satisiactorily explain the
absence, as fossils, of the greater number of the modern genera, but
this circumstance will scarcely account for the distinctness of the
species. None of the species of the English-Tertiaries, from the
Crag to the Eocene, are living forms, and the same appears to
be the case with the species from the German and Italian Oligo-
cene. In his enumeration of the species from, the Miocene deposits
of Austria, Professor Reuss admits but a single recent form, Cary-
ophyliia clavus.*? Not a single one of the species of the West India
Miocene deep-sea Madreporaria is, according to Duncan, a member of
the recent coral fauna, and yet just here a certain stability of physi-
cal conditions would have been supposed to ensure a steady per-
petuation of the species. Similarly, if we except two or three spe-
cies no longer found in the region, the extensively distributed
Deltocyathus Italicus, and Flabellum Cendeanum, from the China
seas, and F. distinctum, from the Red and Japanese seas, all of the
Australian Tertiary (Miocene or Pliocene) Madreporaria are extinct,
and, what is very remarkable, only a very insignificant fraction of
the living local genera is represented specifically in the Tertiary
deposits of that region. Conocyathus sulcatus, a species from the
Oligocene beds of the Maintz basin, is recognised by Duncan as a
member of the recent Australian fauna.”

The restricted specific longevity here indicated is certainly in
marked contrast to what obtains among the Mollusca, where, as is
well known, the recent forms constitute a no inconsiderable per-
centage of the Miocene fauna, and are not even wholly absent from
the fauna of the Eocene series.* And yet the Mollusca would seem
to be much more dependent for their existence upon special physi-
cal conditions of their surroundings than are the corals. The sur-
prising persistence of the Foraminifera is, by way of contrast, not a
little remarkable.

The limited range in time of the species and genera of deep-sea

* The late Mr. Gwyn Jeffreys has recently attempted to show that none of
the Eocene molluscan species are identical with living forms. Whether this be
so or not, there can be no question as to the existence of a limited number of
representative types, which unmistakably bind together the past and present
faunas, and in a manner which we do not find among the corals.

DISTRIBUTION OF CORALS. 24%

corals is likewise exemplified in the case of the reef-builders; but
here the absolute limitations to existence that are set by the physi-
cal aspects of the environs render such a condition in no way sur-
prising; indeed, it is just what might have been expected. Only
a very limited number of the existing generic types date from the
Cretaceous period (Porites, Diploria, Mzeandrina, Goniastreea) and a
still smaller number from the Jurassic (Favia, Heliastreea, Cladocora),
although not unlikely all, or very nearly all, of them belong to some
part or other of the Tertiary period. On the other hand, the num-
ber of generic types that range through the whole series of the
Mesozoic deposits (Isastreea, Thamnastreea, Rhabdophyllia, Thecos-
milia, Cladophyllia, Latimaandra, Stylina) is considerable, and
some of these, as Thamnastreea, Thecosmilia, and Rhabdophyllia,
also pass over into the Tertiaries.

In their geographical distribution the modern reef-builders are
confined to a zone extending on either side of the Equator whose
outer limits are bounded by the isocryme of 68° Fahr., or the line
which marks a lowest average temperature of 68° for all months of
the year. No species, apparently, can endure a lower temperature,
while most of them require for their greatest development a tem-
perature considerably more elevated. Professor Dana has divided
the coral-reef seas into two primary sections, the torrid and the
sub-torrid, the former of which, whose delimitation is fixed by the
isocrymes of 74°, is included in principal part between the twentieth
or twenty-third parallels of north and south latitude, although
reaching in the Red Sea and the Gulf of Mexico considerably
beyond the normal limit. The greatest profusion and wealth of
coral growth is exemplified in this region, and particularly in the
waters of the Central Pacific (Fiji islands, &c.). The astrieas,
meandrinas, porites, and Pocillopore attain here their fullest per-
fection, and with them are associated large beds or masses of ma-
drepores, Pavonie, Fungi, and tubipores, and hosts of other forms
of the most diverse outline and brilliancy of colouring. A deficiency
in the variety of species and genera becomes apparent as we pro-
ceed eastward. Much the same types as occur in the Pacific are
represented in the coral islands of the Red Sea and the Indian
Ocean, and in the East Indies; and in the limited fauna which is
developed along the western coast of America, between Guayaquil
and the peninsula of Lower California, the Pacific element is almost

248 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION,

exclusively represented (Porites, Pavonia, Pociilopora, Dendro-
phyllia, Fungia, &c.). The West Indian coral fauna, on the other
hand, is deficient, either wholly or in great part, in many of the
more distinctive forms of the Pacific Ocean (Astrza, Pavonia, Pocil-
lopora, Fungia), a deficiency in part made good by a special devel-
opment of forms (Diploria, Agaricia, Siderina, Oculina, Cladocora,
Astrangia) which are either wholly wanting, or have only a rela-
tively feeble representation, in the islands of the Pacific. The
madrepores of this region attain to prodigious size. Clumps of
Madrepora palmata, a foliaceous species, have been found to meas-
ure two yards in width, while the branches of the tree-like M.
cervicornis not rarely reach a height of from ten to fifteen feet.
Professor Verrill has pointed out the somewhat remarkable fact that
none of the West Indian species of coral are specifically identical
with the species of the Panama coast, although most, if not all, of
the Florida reef-builders (species of Porites, Madrepora, Meeandrina,
Manicina, Siderina, Agaricia, Orbicella) are also found on the coast
of Aspinwall. Doubtless this difference is in great part attribut-
able to the comparative brevity of the naturai life of the species, as
it is well known that direct communication between the Atlantic
and Pacific oceans, in the region of Panama, was maintained during
the middle or later part of the Tertiary period (Miocene or Plio-
cene), and, if this was so, there can be little doubt that at that time
many of the forms on opposite sides of the present isthmus were
identical specifically. The present differentiation, arising from
isolation, would then date back at least as far as the permanent (or
nearly that) elevation of the separating land-mass, and not improb-
ably to a period considerably antecedent to that. For although,
as has already been seen, the number of recent species that extend
back to the Miocene period is very limited in most parts of the
earth’s surface, yet just in the West India region Professor Duncan
has shown that very nearly ten per cent. of the Miocene coral fauna
is made up of existing species. This being true, we should nat-
urally expect to find, if the isolation of the Panamaic and Gulf
faunas took place in the Miocene period, a considerable intermix-
ture of identical species, which is not the case. It appears prob-
able, therefore, that for some time previous to the final emergence
of the isthmus, whether through the down-wash of sediment or
otherwise, the region was in a measure rendered inimical to coral

DISTRIBUTION OF CORALS. 249

growth, and that but little, if any, transference of species from one
side to the other was effected.* The principal reefs of the sub-
torrid zone, other than the South Pacific, are those of the Bermudas
and the Sandwich Islands, both of which are characterised by a
comparative paucity of specific forms. Most of the species occurring
among the former (Isophyllia, Diploria, Oculina, Siderastrea, Pori-
tes) are West Indian types; in the Sandwich Islands the predomi-
nating forms are Porites and Pocillopora, there being a marked
deficiency in the representatives of the Astrea and Fungia tribes,
and a complete absence of Madrepora. The point most distant
from the Equator about which reef-structures have been noted ap-
pears to be Quelpaert’s Island, situated south of Corea on the
thirty-fourth parallel of north latitude.

In comparing the past with the present distribution of coral
reefs, we are at once confronted with the not very surprising, al-
though all-important, fact that the areas of such distribution in no
way correspond with those distinctive of the modern seas. The
extension of reefs northward to points far beyond any now occu-
pied by such structures is practically proof positive of the existence
of thermal conditions very different from those which obtain at the
present day, and of a much more equable climate, with a more
elevated temperature, than is now found in the higher latitudes of
the earth’s surface. Paleozoic reef-building corals have been found
in Eurasia (Scandinavia, Russia) far above the sixtieth parallel
of latitude, and a number of genera even in Spitzbergen, Nova
Zembla, and Barentz. Islands; Lithostrotion was obtained by the
officers of the British North-Pole Expedition, under command of Sir
George Nares, at a point beyond the eighty-first parallel of latitude.
The reef-building corals of the Silurian and Devonian periods—
Favosites, Heliolites, Halysites, Syringopora, Cyathophyllum, Acer-
vularia, &c.—have left traces of their profuse development in seas
as far north as Canada and Scandinavia, but it would perhaps be
straining a point to infer from their occurrence there that climatic
conditions in any way identical with those existing in the modern
coral zones prevailed during those periods in high northern lati-
tudes. Our knowledge respecting the habits 2nd affinities of these
ancient organisms is still much too limited to permit of a positive

* All the species described by Duncan from the Oligocene deposits of the

island of St. Bartholomew are extinct.
12 =

250 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

determination of the question. Yet the recession southward of reef-
structures, in the making of which the modern type corals were
largely involved, during the succeeding periods of the Mesozoic
and Cainozoic eras, seems to indicate that this must have been the
case; for as far as the evidence from these later structures goes
there can be no reasonable doubt as to a progressive lowering of the
oceanic temperature correlatively with an advance in time. And if
this was the case from the Triassic period onward, there is every
reason to suppose that it has been so from a much earlier period.
Reef-structures appear to have been very extensively developed
in South-Central Europe during the Triassic period, and not un-
likely much of the giant dolomites of the Tyrol, whose abrupt and
pinnacled masses so wonderfully diversify the face of the country,
is the product of the unceasing labours of the minute polyp. In the
succeeding Jurassic period a more or less continuous coral sea oc-
cupied a considerable portion of Western and Central Europe, as is
evidenced by the vestiges of reefs which still remain in England,
France, Germany, and Switzerland. During the deposition of the
Oolites the reef-structures appear to have attained their maximum
development, the shallow coral sea, with its atolls and barrier reefs,
extending as far east as the Carpathian Mountains, and covering
much of the region now occupied by the Alps. The British area
was still favourable to the growth of the coral polyp. With the
beginning of the Cretaceous period there would seem to have been
a gradual deepening of the oceanic bottom to the north, and the
introduction of conditions inimical to the proper development of
coral life, for the number and extent of the reefs occurring there
are comparatively very limited; a Southern European belt, on the
other hand, is very coralliferous. No doubt the gradual lowering
of the oceanic temperature had much to do with this recession,
more, in fact, than the simple lowering of the oceanic bottom,
since the latter, if gradual, while it would almost certainly check
a lateral extension of coral structures, would scarcely tend towards
their complete or wholesale obliteration. The coral formations
would still persist with the conversion of connected land-masses
into islands, and after the complete submersion of these last, just
as we now find them over the deeper oceanic abysses. That the
temperature at this period was not entirely too low, however, in
all parts of the region under consideration, is proved by the Upper

DISTRIBUTION OF CORALS. 2501

Cretaceous reefs of Maestricht, Faxoe, and the neighbourhood of
St. Petersburg, and by the limited vestiges of such whicl: still
mark the Eocene deposits of the typical English basin. The reefs
of the Eocene period find their greatest extension in Southern
Europe—from the northern flanks of the Alps and Pyrenees south-
ward, and eastward through the Crimea, Egypt, Syria, Arabia, and
East India. The more extensive European reefs of the Oligocene
period are those of Oberburg, in Styria, and Northern Italy (Crosara,
Castel Gomberto, &c.); Miocene reef-patches still exist in Spain,
Southeastern France, Northern Italy (Superga), the Vienna basin,
and Hungary, the larger structures, however, occurring in the region
farther to the south (Malta, Asia Minor, the West Indies, Java).
At the close of this period the reefs appear to have still further
receded, and in the Pliocene they completely vacated the present
continental area. Dr. Duncan has remarked the existence in the
Table Cape Tertiaries of Tasmania (Miocene ?) of reef-building
corals (Heliastreea, Thamnastreea) at a point removed some fifteen
degrees of latitude south of the coral isotherm of that region.**

The limited range in depth—not exceeding twenty fathoms—of
reef-building corals is certainly extraordinary, and something that
still remains in the nature of a puzzle to the naturalist. That it is
not, either wholly or in great part, dependent upon conditions of
temperature is conclusively proved by the total absence of such
organisms in depths beyond one hundred and twenty feet where a
temperature considerably above that required for coral growth still
prevails (Pacific Ocean, Red Sea). Possibly a movement, or want
of movement, in the oceanic waters has something to do with this
abrupt limitation.

The Alcyonaria or Octocoralla, except in so far as some of the
forms until recently classed with the Tabulata may be considered
to belong to this group—as Halysites and Syringopora, supposed
to be allied to the organ-pipe (Tubipora), Heliolites to Heliopora—
acquire but little geological importance. The pennatulids appear
to have one or more representatives (Pavonaria) extending back to
the Cretaceous period, and a limited number (Graphularia ?) also in
the Eocene. The sea-fans (Gorgonide), whose brilliantly coloured
masses constitute such a striking feature of the coral patches of
both the Atlantic and Pacific oceans, are not positively known be-
fore the Miocene period (Primnoa, Gorgonella). The genus Isis

252 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

occurs in the Cretaceous deposits, and Corallium, to which the
red coral of commerce belongs, already in the Jurassic. The
distribution of the latter genus appears to be at the present time
confined principally to the Mediterranean Sea, where it ranges in
depth from shallow water (twenty-five to fifty feet) to water over
one thousand feet, and to the Atlantic off the northwest of Africa.
A species of the genus (Corallium stylasteroides) has been obtained
off the coast of Mauritius, and another from Japan (C. [Pleuro-
corallium] secundum). The officers of the ‘‘ Challenger” expedi-
tion obtained water-worn fragments at Banda and the Ki Islands,
indicating the existence of the genus in the Malay Archipelago.

BRACHIOPODA.

The most detailed information that we possess respecting the
geographical and bathymetrical distribution of the recent Brachio-
poda is furnished by Davidson in his report appended to the nar-
rative of the ‘‘ Challenger” expedition (1880). Of the one hundred
and thirty-five species and varieties (referable to some twenty genera
and sub-genera) here recognised, whose distribution covers all parts
of the oceanic surface, from Spitzbergen (Terebratella Spitzbergensis,
Terebratulina caput-serpentis) and Franklin Pierce Bay (latitude
79° 25’; Rhynchonella pisittacea) on the north to Kerguelen Island
and the Straits of Magellan on the south, there are few, if any,
that can in any way be considered truly cosmopolitan, although
species of broad distribution are not exactly uncommon. Tere-
bratulina caput-serpentis is perhaps the most widely distributed of
all the known forms, its habitat comprising the Arctic seas of both
the Eastern and Western Hemisphere (Spitzbergen, Davis Strait),
the Atlantic coast of Europe as far south as Spain, Jamaica, Corea,
and Australia. Terebratula Wyvillii is found off the coasts of South
Australia, the Falkland Islands, and Chili. As a rule it may be
said that the north and south extension of a species is greater
than the east and west extension, a condition doubtless due in
principal part to the general disposition of the land areas in this
direction. Arctic or cireumpolar species have naturally a broad
lateral dispersion. Species restricted in their habitat to shallow
water are as a rule much more sharply circumscribed in their range
than those inhabiting the greater depths, as might reasonably have
been supposed. Localisation to limited coast lines, as Japan,

DISTRIBUTION OF BRACHIOPODA. 253

Corea, Florida, is of frequent occurrence, and not unlikely certain
species may be even restricted to special bays or inlets of the sea.
But few other than boreal or hyperboreal species are fuund inhabit-
ing opposite sides of the same oceanic basin; notable exceptions
are Platydia anomioides, whose range embraces the Mediterranean
and West European coasts and the Florida reefs, and Thecidium
Mediterraneum, from the northwest coast of Africa and Jamaica,
both with a vertical range falling within six hundred fathoms. The
most striking instances of areal discontinuity are furnished by
Terebratella Frielii (near Halifax, one thousand three hundred and
forty fathoms, and the Philippine Islands, one hundred and two
fathoms) and Discinisca stella (Singapore, Philippines, Japanese and
Chinese seas, and Bermuda), the former a deep-sea species, and the
latter restricted to shallow water (seventeen to forty-nine fathoms).
From such data as have been given, it would appear that the
oceanic abysses form an insuperable barrier to the passage of the
Brachiopoda; how the transference was effected in the case of the
few exceptional species that have been indicated remains a matter
of conjecture.

In their bathymetrical distribution the Brachiopoda affect the
most diverse conditions of existence. While some forms (all or
nearly all the species of Lingula, for example) appear to be incapa-
ble of living in greater depths than a few fathoms below water-line,
others, again, seem just as incapable of leaving the greater depths.
Discinisca Atlantica, a widely spread deep-sea species, has thus far
been found only in water exceeding six hundred and fifty fathoms,
and Terebratula Wyvillii, an equally wide-spread and abundant
species, in water exceeding one thousand fathoms. Other species,
on the other hand (Terebratula vitrea, 5-1456 fathoms; Terebratu-
lina caput-serpentis, 0-1180 fathoms), seem capable of accommo-
dating themselves to the greatest variety of depths. The species
exhibiting the widest range of accommodation are such as have in
part a boreal or arctic habitat; in other words, forms which find
the same water-temperature at the surface and at varying depths
beneath the surface. Per contra, the species having the most lim-
ited vertical range are those confined to the warm waters, tropical
and sub-tropical. From this it follows that distribution in depth is
effected primarily by conditions of temperature, and not by consid-
erations of light, food-supply, &c., as has been urged by Fuchs and

254 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

others. A marked exception to the above law is furnished by the
type form of Terebratula vitrea, of the Mediterranean and adjacent
seas, whose range varies between five and fourteen hundred and
fifty-six fathoms. The greatest depth whence any brachiopod has
been obtained is twenty-nine hundred fathoms (Terebratula Wy-
villii).

Of about one hundred and seven species with whose range we
are acquainted, fifty-seven, or more than one-half, are restricted to
depths of under one hundred fathoms, and of these a large propor-
tion properly belong to the shore-line, or to a zone of from five to
fifteen fathoms water. There are twenty-one species (or varieties)
whose range extends to, or above, five hundred fathoms; ten with
a range of one thousand and upward; and three with two thousand.
These facts indicate, as Mr. Davidson has pointed out, that the
‘ oreater bulk of known species live at comparatively small or mod-
erate depths,” and that ‘‘ Brachiopoda are specifically rare at depths
varying from five hundred to twenty-nine hundred fathoms.” As
to numerical distribution we find, as the result of the ‘‘ Challenger’s ”
explorations, that in ninety-nine dredgings, taken in water of from
one to five hundred fathoms, Brachiopoda were brought to the sur-
face about twenty-three times; in thirty dredgings, of five hundred
to one thousand fathoms, four times; in ninety-four dredgings,
of one thousand to two thousand fathoms, nine times; and in one
hundred and seventy-six dredgings, of two to three thousand fath-
oms, only six times. It is seen here, therefore, that the numeric
diminution keeps pace with the specific, and that practically the
Brachiopoda cease to abound in depths exceeding five hundred
to six hundred fathoms. The proper appreciation of these facts be-
comes of prime importance when discussing the nature of geologi-
cal deposits containing brachiopod remains.

In respect of numerical development and broad distribution,
both in time and space, the Brachiopoda constitute, for the geolo-
gist, the most important landmark in the determination of his hori-
zons. Beginning with the very earliest fossiliferous formation, the
Cambrian, and there already in nearly the bottom bed (St. David's),
they continue throughout all time, and if, during the more recent
geological periods, they have suffered rapid diminution, both in
actual numbers and the variety of forms, they are still sufficiently
abundant and varied to indicate that a long period must elapse

DISTRIBUTION OF BRACHIOPODA. 255

before their final, or even approximate, extinction will have been
reached. Indeed, if specific variation be considered a just criterion
in the determination of the question of development or extinction,
it may be reasonably doubted whether we are not now actually
more remote from the apparent closing period of the existence of
this group of animals than we were at the beginning of the Tertiary
epoch, possibly a million or more years ago. Some sixty species
and varieties, referable to ten genera, of brachiopods have been
described by Davidson (1870) from the Tertiary deposits of Italy,
and these constitute by far the largest number furnished by any one
country of all the Tertiary forms that have thus far been described.
England has but seven species, and France and Germany scarcely
more, while the United States have not even as many. The num-
ber of distinct forms found in the present Mediterranean waters is
about fifteen, or only one-fourth the number found in the Italian
Tertiaries; but it must be recollected that the periods of time which
we are here comparing are of very unequal duration, the ‘“ recent”
period being only a mere figment of that indicated by the Tertiary
formations. If to the recent and Quaternary species we add those
found in the Upper Pliocene we will have a total of twenty-one
species, which will then considerably outnumber the species from
the entire Eocene series (thirteen or seventeen), and only fall eight
or nine short of the total number from the combined Lower, Middle,
and Upper Miocene. As to generic development, we find the Italian
Tertiary species to belong to ten genera or sub-genera, to wit: Tere-
bratula, Terebratulina, Waldheimia, Terebratella, Megerlia, Platy-
dia, Argiope, Thecidium, Rhynchonella, and Crania, all of which,
except Terebratella and Rhynchonella, are still found in the Medi-
terranean waters.* The number of Tertiary brachiopod genera and
sub-genera thus far recognised is fourteen,** as against twenty or
more of the present day.

The earliest known Brachiopoda, or those of the Cambrian pe-
riod, belong almost exclusively to the group of the Brachiopoda
inarticulata (Pleuropygia), forms in which the shell is horny-calca-
reous and devoid of a dental articulation—Lingula, Lingulella, Lin-
gulepis, Obolella, Kutorgina, Acrothele, Acrotreta, Discina. The
remains of Orthis (and Orthisina ?) alone of the Brachiopoda articu-

* Thecidium Mediterrancum appears to belong only to the African side of
the Mediterranean,

256 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

lata occur associated with these lower forms. Up to 1868 there were
catalogued some one hundred and twenty-six species (Bigsby) from
the Cambrian deposits of the world, most of which belonged to
Canada, Scandinavia, and the British Isles (twenty species in 1880,
Etheridge). The prodigious development of the Brachiopoda in
the Silurian period, apart from the mere consideration of numbers,
is important, as representing the climax of development in this re-
markable group of organisms. Henceforward they show a pretty
steady decline, although the rate of decline for the various periods
is different for different regions of the earth’s surface. The fact
that there are some fifteen hundred or more species in the Silurian
deposits, of which considerably over five hundred are already rep-
resented in the Lower Silurian, and less than two hundred in the
Cambrian, is extraordinary, whichever way it be considered, for,
whether in the Cambrian we were somewhere near the beginning of
life, or very distantly remote from it, as is much more likely to
have been the case, the difficulty of explanation is in no wise af-
fected. In either case the suddenness of the Silurian apparition
is the same, and this is the more remarkable, seeing that there is
scarcely any advance in the number of species of the Upper as com-
pared with the Lower Cambrian. In the Bohemian Silurian basin
Barrande enumerates six hundred and forty species, whereas in the
Cambrian there are but two !

It is usually assumed that the Silurian species of brachiopods
are vastly in excess of the Devonian, but the latest revised tables
seem to indicate that this is not the case, and, indeed, it is not
improbable that the numerical balance will be found to weigh on
the other side. The number of genera is, however, greatly re-
duced, from about seventy to fifty, and this reduction is further
carried into the Carboniferous period, where we have but forty
genera, representing some eight hundred to nine hundred species.
That there should have been, so soon after the climax had been
reached, such a rapid decline is not a little surprising, but yet the
suddenness of this decline is in no way comparable with the sud-
denness of the apparition already noticed in the Silurian. More
surprising is the almost total absence of forms from the Permian
deposits, where the deficiency can only partially be explained by
the circumstance of the limited extent which these deposits occupy,
and the special conditions under which their formation was effected.

DISTRIBUTION OF BRACHIOPODA. 257

The gradational passage between the brachiopod faunas of the
Paleozoic and Mesozoic eras is probably more complete than in the
case of any other group of the Invertebrata. Indeed, were it not
for considerations drawn from other and higher groups of animals,
the Triassic deposits would from this testimony alone be more
properly relegated to the former than to the latter of the two eras,
for with very insignificant limitations—Thecidium, Waldheimia, be-
ing exceptions—all the specific forms of this period belong, if not
to such genera as are absolutely peculiar to the Trias—Koninckia,
Ceenothyris—to types which are not only represented in the Paleo-
zoic formations, but in most instances are eminently distinctive of
them. It must be noted, however, that by far the greater number
of the Paleozoic types had already ceased to exist, and such as still
linger on, except the few more persistent types, like Lingula, Dis-
cina, Crania, and Rhynchonella, rapidly near extermination. The
Cretaceo-Jurassic brachiopods constitute, strictly speaking, a single
series, the members of which belong mainly to the genus Rhyn-
chonella, and to a number of closely inter-related genera of the
family Terebratulide.

Perhaps the most striking fact taken in connection with the
geological distribution of the Brachiopoda is the remarkable varia-
tion shown in the adaptation of different groups to their surround-
ings. While certain generic types—those of the family Obolide,
for example—appear to have been incapable of surviving for more
than a comparatively brief period of time, dying out with the sud-
denness of their introduction, others, again, like the Lingula and
Discina, have persisted throughout all time, and with such slight
modification of structure as to render it difficult in some instances
to determine specific differences between the most ancient and the
most modern forms. That the least complex or most primitive
forms of brachiopods should exhibit the greatest persistence might
have been naturally expected, but it is nevertheless rather singular
that the number of persistent types following these earliest pre-
cursors of a class should be so very limited in number. This per-
sistence appears the more marked, too, when we reflect how very
narrowly circumscribed in their vertical range are the majority of
the species. Thus, out of the vast number of described forms,
comprising possibly not less than five thousand distinct species,
only a bare handful pass from one formation to another, and, in-

258 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

deed, a very large proportion of the species appear to be restricted
to special zones of a given formation.*

In their geographical relations the ancient Brachiopoda differ
essentially from those of the modern seas by reason of their broad
horizontal distribution. Cosmopolitanism, or something approach-
ing it, if not exactly the rule, was at least distinctive of a very
large proportion of the species, a circumstance undoubtedly due
to more equable conditions of environment, and the absence of in-
terposed barriers to migration. This broad dispersion is perhaps
nowhere better illustrated than in the case of the extinct fauna of
China. Thus, out of a total of thirteen Silurian and twenty-four
Devonian species described in Richthofen’s work, no less than ten
of the former and sixteen of the latter are also found in Western
Europe; and, further, of the Devonian species, about eleven, or
nearly fifty per cent., are cosmopolitan. Again, of about twenty-
five Carboniferous species, some fifteen (or sixty per cent.) are
common to North America, and about an equal number are cosmo-
politan.

MOLLUSCA GENERALLY.

The more salient features connected with the distribution of
the animals of this class have already been considered in our treat-
ment of Geographical Distribution and Brachiopoda, and do not
require restatement. It has been seen that the principal factors
involved in this distribution are temperature and the presence or
absence of continuous coast-lines along which migration might be
effected; to these two categories may also be added the circum-
stance of light (or darkness), but to what extent this influence is
exerted has not as yet been determined.

The attempted subdivision of the oceanic area into a number
of distinct regions (provinces), each one characterised by a more or
less peculiar assemblage of molluscan forms, while undoubtedly
indicating a certain amount of faunal individuality, is still far from

* A more critical and impartial revision of the species will not unlikely
materiaily increase tne number of such connecting forms, and forms of even
widely separated formations may be found to be iaentical. Thus, Davidson
(‘‘ British Fossil Brachiopoda,” ‘‘ Paleont. Soc. Rep.,’’? 1884, p. 896-398) ad-
mits that some of the forms of the Mediterranean Terebratulina capui-serpeutis
may only be varieties of the Cretaceous T. striata; and, likewise, that the
recent Rhynchonella nigricans and some Cretaceous and Jurassic forms are so
closely related to each other ‘‘ that we are at a loss to define their differences.”

DISTRIBUTION OF MOLLUSCA GENERALLY. 259

satisfactory. The notion of absolute limitation, which was enter-
tained when the provinces were first instituted, sees its own dis-
proof in the records of almost every new exploration, and the
annihilation of the very essentials which were considered requisite
for the framing of zoogeographical boundaries. The more phil-
osophical interpretation of the nature of species, and the more
general recognition of the fact that certain forms considered to be
peculiar to a definite region or district may also occur elsewhere, or
where they are assumed not to belong, even if they show no varia-
tion in their characters, have done much to render the generally ac-
cepted provinces illusory. It is true that many of the regions now
recognised by conchologists are strictly defined as such, but it is
equally true, using the generally accepted criterion in the formation
of provinces—the inclusion of a certain proportion of peculiar
species—that new provinces, with entirely different boundaries,
and with as much claim to faunal peculiarity, might be instituted
in place of others that are also fully recognised. Until greater
harmony is reached by malacologists in their realisation of species,
and more regard paid to the facts of nature rather than to precon-
ceived notions, any attempt at delimitation of zoogeographical
boundaries must prove at best only half satisfactory.

The Mollusca proper—Lamellibranchiata, Gasteropoda, Ptero-
poda, and Cephalopoda—of which there are some 30,000, or more,
recent species, have a world-wide distribution, being found in
almost all parts of the earth’s surface that have thus far been vis-
ited by man. From beyond the eighty-second parallel of north
latitude to the Equator, and from the surface of the sea to a depth
of sixteen or seventeen thousand feet, and to an equal height above
it on the land, they are everywhere more or less abundant. Despite
the extraordinary range which certain species are reputed to enjoy,
there is yet scarcely a single one that is in any way entitled to the
claim of cosmopolitanism, nor, indeed, any, if we except possibly
some pelagic species (pteropods, cephalopods), and the members of
the Arctic and Antarctic faunas, which occupy a complete circum-
ferential zone of the globe.*

* A further exception may possibly have to be made in favour of some of
the abyssal species, concerning whose distribution we know practically noth-
ing. Mytilus edulis and Saxicava arctica are perhaps the most strictly cos-
mopolitan species known.

260 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

This condition is somewhat surprising in view of the free-
swimming character of the molluscan embryo, and the fact that a
number of forms of tropical habit have in some way managed to
gain access to the opposite shores of the oceanic basin. Many of
the forms belonging to the Caribbean province recur on the west
coast of Africa, and the Dolium galea of the Mediterranean is also
a member of the Brazilian and Antillean faunas. In what particular
manner the transport was effected in the case of these few favoured
species it is impossible even to conjecture, but it appears to point
to a remarkable vital tenacity on the part of the embryo. Still
more surprising, and entirely inexplicable, is the distribution of
the fifteen or more species (including a dozen species of the genus
Triton) whose common habitat is the Indian Ocean and the West
Indian sea, when no connecting representative is found in the
intermediate area. This is perhaps the most remarkable instance
of specific areal discontinuity known, and contrasts sharply with
what is observed on the west coast of America, where, of the
very rich fauna of the Panamaic province, with no intervening
barrier, an only equally small number of species is held in common
with the Indo-Pacific region. The species of the far south, on
the other hand, are largely similar, despite the absence of existing
land-connection. From the occurrence of identical forms in New
Zealand, the Magellan district, and the isolated tracts represented
by the Kerguelen, Marion, Crozet, and Prince Edward islands,
Fischer argues ** that we have represented here the disrupted parts
of a former Antarctic continent, along which specific diffusion was
primarily effected. But there scems to be no reason why the pres-
ent distribution might not at least in part be explained on the
assumption of diffusion along the oceanic bottom—where the differ-
ence between surface and bottom temperature is no longer extreme
—seeing that we have here also a number of distinctive Arctic or
northern types represented (Chiton Belknapi, Lasza rubra, Tere-
bratulina septentrionalis, Terebratula vitrea, var. minor). The most
southerly mollusk thus far met with is a pteropod, Limacina ?
cucullata, which was obtained by the Wilkes Exploring Expedition
on the sixty-sixth parallel of south latitude.

Instances of specific limitation are exceedingly numerous, and
particularly characterise insular faunas. To such an extent is this
the case that it may be said that almost every oceanic island or

DISTRIBUTION OF MOLLUSCA GENERALLY. 261

island group, when surrounded by deep water, has its own dis-
tinctive molluscan fauna. This we see in such islands as Cuba,
Jamaica, Hayti, Madagascar, New Caledonia, the Philippines, &c.,
where the faunal peculiarity manifests itself not only among species,
but extends largely to genera. Even the very much smaller islands
of Malta, Cos, Naxos, Corfu, Zante, Lesbos, Rhodes, &c., in the
Mediterranean, have a full share of species which are not found
elsewhere. The Atlantic island groups of the Azores, Canaries,
and Cape Verde are still more marked in their individuality. Both
species and genera are here largely restricted to the several groups,
and of the forms which ally them with the European fauna a large
number are such as have been introduced by man. The com-
mon Holarctic fresh-water genus Unio is entirely wanting, and,
indeed, in the Azores there is not a single fluviatile form repre-
sented. Of the eighteen species of Bulimus which constitute the
entire non-marine molluscan fauna of the Galapagos Islands ten are
restricted to single islands of the group. The genus Achatinella,
which is restricted to the Sandwich Islands, has there some two
hundred and eighty-eight species or varieties, or very nearly three-
fourths the number of the entire molluscan fauna of the region.
This faunal individuality, the result of a long-continued isola-
tion of the various island groups, permitting of a gradual but
steady evolution of new and independent forms, does not extend
to Great Britain, whose separation from the continent has been
effected in a comparatively recent period, and after the constitution
of the contiguous faunas. There appear to be but two molluscan
species (Limnzea involuta and Assiminea Grayana) that are distinc-
tive of this island group. Similarly, the identity existing between
the Peninsular and North African faunas points, apart from all
other evidence, to the recent formation of the Strait of Gibraltar.
The natural barriers which interpose themselves to the free
migration of the terrestrial and fluviatile Mollusca, such as inter-
cepting land and water areas, elevated mountain-chains, or deserts,
are apparently much more numerous than those affecting marine
forms, and account for the comparatively limited range of most
species. Yet it is remarkable how far certain forms or types of
forms have spread. Thus, the two most important genera of land
and fresh-water mollusks, Helix and Unio, and among fresh-water
pulmonates, the genera Limnza, Physa, Ancylus, and Planorbis,

262 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

have an almost world-wide extension, many of the species even
appearing in widely separated parts of two or more continents.
Still, we know of no truly cosmopolitan species of these groups,
although through artificial transport many of the forms have been
made to spread far beyond the limits of their natural domain.
Helix similaris, indigenous to Eastern Asia, is now largely found in
Malaysia, Polynesia, Australia, the Seychelles, South Africa, the
Antilles, and Brazil, and as nearly an extensive range is claimed
for Ennea bicolor. The common garden-snail of Europe (Helix
aspersa) has been naturalised in Algeria, the Azores, Brazil, and
California, and human agency has, doubtless, been largely involved
in the dissemination of the small moss-inhabiting Helix pulchella,
which now inhabits the greater part of the continent of Europe,
the Caucasus, Madeira, the region of the Cape of Good Hope, and
nearly all Northern North America.

Bathymetrical and Hypsometrical Distribution.—There are
five zones of distribution usually recognised in the oceanic waters,
as follows: 1, the Littoral Zone, or that existing between tide-marks
—the habitat of the periwinkle, limpets, sand-clam, cockle, mussel,
and barnacle; 2, the Laminarian Zone, extending from low-water
mark to about fifteen fathoms, and characterised by a dense growth
in many places of sea-weed and tangle—the haunt of the vegetable-
feeding Testacea and of various nudibranchs, and the home of the
oyster; 3, the Coralline Zone (from fifteen to forty or fifty fathoms),
the zone of the encrusting Algze (nullipores), and of the large car-
nivorous Gasteropoda (Buccinum, Fusus, Pleurotoma, Natica, &c.);
4, the Deep-sea Zone, or that of the Brachiopoda and deep-sea corals
(from fifty to two hundred and fifty or three hundred fathoms);
and, 5, the Abyssal Zone, from three hundred fathoms to the oceanic
floor, throughout which the shells are generally of small size, trans-
lucent (thin), and white or but feebly coloured. The visual organs
are here exceptionally devoid of pigment, and blindness has been
noted in a few species of normally seeing gasteropods. It might be
doubted, however, whether the last two divisions ought not more
properly to constitute a single division, considering the large pro-
portion of genera and species which pass from the shallower to the
deeper parts. Dall, from the data furnished by the dredgings
made in the Gulf of Mexico by the steamer ‘‘ Blake” (1877-’78),
affirms that fully twenty per cent. of the molluscan species obtained

DISTRIBUTION OF MOLLUSCA GENERALLY. 263

from that region enjoy a vertical range extending from less than
fifty to two hundred and fifty and two thousand fathoms,* which
would then give a very high proportion for those connecting the
fourth and fifth zones.

At depths of from three hundred to one thousand fathoms mol-
lusks are still numerically very abundant, although the number of
species very rapidly diminishes. From an extreme depth of 2,435
fathoms (14,610 feet) the ‘‘ Porcupine” obtained but five species,
and from 2,900 fathoms (17,400 feet) the ‘‘ Challenger” dredged
only two—Semele profundorum and Callocardia Pacifica. In the
greatest depths the Lamellibranchiata (principally represented by
the families Arcade, Nuculide, and Pectinid, the genera Pec-
chiolia, Nera, &c.) appear to preponderate over the Gasteropoda,
whose dominating forms are tectibranchs and the Scaphopoda, and,
among the prosobranchs, the genera Fusus and Pleurotoma. +

The question whether the abyssal fauna is of a generally uni-
form type, marked by identical or representative species extend-
ing from pole to pole, as was first suggested by Lovén, and subse-
quently admitted by Sir Wyville Thomson, still lacks the necessary
data required for its solution. The extremely broad or antipodal

* “Bull. Mus. Comp. Zool.,’”? vi., 1880. In a supplemental note only
fifty-one species (out of four hundred and sixty-two) are recorded whose
range covers both the littoral and the abyssal zones, thereby reducing the
ratio to eleven per cent.

+ The researches of Edgar Smith and Boog Watson upon the Mollusca
obtained by the ‘‘ Challenger’’ reveal some very remarkable instances among
this group of animals of ready adaptability to the most varying conditions of
depth, and of discontinuous habitation. Silenia Sarsii was dredged about
1,100 miles southwest of Australia in water of 1,950 fathoms, and again off the
mouth of the Rio de la Plata, in 2,650 fathoms; Verticordia Deshayesiana,
found off Pernambuco in water of 350 fathoms, was also dredged off Cape
York in 155 fathoms; Petricola lapicida, a well-known West Indian form,
recurs off the North Australian coast (seven fathoms) ; and Nuculina ovalis, a
fossil of the Suffolk Crag, reappears in the waters of the Cape of Good Hope
in twenty fathoms. Venus mesodesma, a shore species, descends to 1,000
fathoms, while the range of Lima multicosta extends from two to 1,075 fathoms,
and of Arca pteroessa from 390 to 2,050 fathoms (the West Indies and the
North Pacific, respectively). The total number of lamellibranch species ob-
tained in depths under 100 fathoms was 384; in depths between 100 and 500
fathoms, 148; between 500 and 1,000 fathoms, 24 (ten stations) ; and between
1,000 and 2,900 fathoms (thirty-three stations), 70. (‘‘ Challenger’’ Reports,
* Zoology,” xiii., 1885.)

264 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

distribution of many of the species has led to the belief that such
is the case, but, on the other hand, certain facts that have recently
been brought to light seem to point in the contrary direction.
Thus, it has been shown by Mr. Dall that of the species composing
the abyssal fauna of the Gulf of Mexico only ten per cent. are such
as may be termed boreal, a very small proportion to what might
have been expected, were it to be assumed that the peopling of
the cold bottom wastes was effected by a descent from the polar
regions. On the other hand, thirteen per cent. were found to be
tropical, and seventy-five per cent. uncharacteristic, forms. It is
concluded from these facts, and from the circumstance that ‘‘the
tropical forms belong to the same groups as those characteristic of
the local littoral mollusk fauna,” that in all probability ‘‘the
abyssal regions have local faune proper to their various portions,
and that a universal exclusive abyssal fauna, so far as mollusks are
concerned, does not exist.” This conclusion, which was concurred
in by the late Mr. Gwyn Jeffreys, receives further support, it is
claimed, from the distinctness of the ‘‘ Challenger” Mollusca as
compared with those of the ‘‘ Blake.”

The hypsometrical distribution of the Mollusca is governed
almost exclusively by conditions of climate and food-supply, the
influence of the latter being manifest in the intimate relation
which binds many of the species to the plants upon which they
habitually feed. Thus, in the Higher Kabylia, Aucapitaine has
framed three molluscan zones, each corresponding to a particular
plant growth: 1. The zone of the ash, olive, and pomegranate
(450 to 2,100 feet); 2. That of the oak and pine (2,100 to 3,600
feet); and, 3. That of the cedar and green turf (3,600 to 7,200
feet). The upper limit to which mollusks attain on the continent
of Europe (Alps) is about eight thousand feet, somewhat below
the line of perpetual snow ; along the region of the equatorial
Andes and the Himalayas the line is placed at about twice this
height, also approximating the snow-level. Five species of fresh-
water shells, of the genera Planorbis, Paludestrina, and Cyclas, were
found by Morelet to inhabit Lake Titicaca at an elevation of nearly
13,000 feet, while from the Himalayas Anadenus Schlagintweiti
has been obtained at a height of 16,500 feet, and Limnza Hookeri
at 18,000 feet. Of the North American land shells the representa-
tives of extreme hypsometric range appear to be Pupa alticola and

GEOLOGICAL DISTRIBUTION OF MOLLUSCA. 265

Vallonia pulchella.°* The various hypsometric zones that have been
established by conchologists differ at almost all parts of the earth’s
surface, and are of but local import. The shells of the more
elevated mountain-summits are many of them, or mostly, of types
which are found at lower levels in regions of reduced average
annual temperature, following the well-known law of climatic
dispersion which we recognise among plants. Vertigo alpestris,
an inhabitant of Scandinavia, reappears in the Alps of Switzerland,
although completely wanting in the intermediate regions; and,
similarly, many Alpine summits hold identical or representative
species which are wanting in the connecting lowlands.

Geological Distribution.—The most salient fact that presents
itself in connection with the past distribution of the Mollusca is
the reversed order to what might have been expected of the suc-
cessive development of its primary classes. Thus, almost every-
where, the Cephalophora, or head-bearing mollusks, antedate by
one full period the Acephala, or headless forms, which indisput-
ably represent a lower grade of organism; and among themselves
the first to attain a maximum development are the cuttle-fishes
(Cephalopoda), which are.structurally the highest. But two species
of this group—an Orthoceras and a Cyrtoceras—are positively known
from the Cambrian formation, while in 1868 Bigsby enumerated no
less than one hundred and thirteen species of Gasteropoda as belong-
ing to the same period of time. On the other hand, the total
number of gasteropod species credited by the same author to the
Silurian deposits is about eight hundred, whereas Barrande has
described upwards of eleven hundred species of Nautilids from
the Upper Silurian deposits of Bohemia alone. As has already been
intimated, there is a marked deficiency of Cambrian lamellibranchs,
and even in the Silurian formation the number of species is com-
paratively limited. Bigsby, in 1868, enumerated, all in all, some
six hundred and thirty-six species, or but little more than one-half
the number of Upper Silurian cephalopods of the Bohemian basin.
The complete differentiation which the different classes of the
Mollusca had already attained in the Silurian period argues for a
great antiquity beyond that period of the members of this group.
To what extent the time measured by the Cambrian period, and
the interval intervening between it and the Silurian, may have been
effective in bringing about the various changes, cannot be at pres-

266 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

ent determined; it would appear at first sight as though the length
of its duration were suflicient, for how otherwise could we in-
telligently explain the total or nearly total absence of the members
of at least two of the molluscan group from deposits in which the
representatives of other groups are sufficiently abundant? (One
fact, however, must not be lost sight of in this connection, and
that is, that in these earliest deposits the obliteration of organic
remains has been most excessive, and that not improbably the
absence of the required forms is to be attributed rather to the
destruction of parts than to an actual non-existence in the region.
For the present it is impossible to affirm whether the Cephalophora
came into existence before the Lamellibranchiata or not, but the
evidence scarcely appears sufficient for considering the latter as a
race derived by degeneration from the former, as has been pre-
sumed by Professor Lankester.

The sudden decline of the Cephalopoda (Nautilide) after the
close of the Silurian period is very remarkable, and scarcely less
so their rehabilitation under the form of their successors, the Am-
monitide, in the deposits of the Mesozoic era; Barrande enumerates
but two hundred and forty-two species from the Devonian forma-
tion, more than one-half of which belong to the genus Orthoceras,
and the remainder principally to the genera Cyrtoceras, Gyroceras,
and Gomphoceras. About an equal number are indicated from the
deposits of Carboniferous age, where also we find much the same
genera represented, although with different specific relations. The
genus Nautilus now for the first time acquires any importance, and
it and Orthoceras alone of the limited surviving members of the
family of the Permian period transgress the boundaries of the
Paleozoic era. The latter genus disappears early in the Trias,
while the former steadily increases in number, until in the Creta-
ceous deposits it attains its maximum development, with a repre-
sentation of some sixty or more species.

The displacement of the Nautilide by the Ammonitide is, if
nothing more, certainly an interesting circumstance, and leads one
to inquire what special advantage the latter may have possessed
over the former in the struggle for existence, by means of which
they triumphed over their predecessors. For there can be little
question that the Ammonitide, despite certain peculiarities in their
structure, which are not as yet comprehensible to us, are the truly

GEOLOGICAL DISTRIBUTION OF CEPHALOPODA. 267

modified descendants of the nautiloids, a transition to which ap-
pears to have been effected by way of the genus Goniatites and
those forms of the Carboniferous period (India and Texas) which,
like Arcestes, have the sutural plication intermediate between what
is seen in Goniatites (Silurian-Permian) and Ceratites (Triassic).
Just where the embranchment from the nautiloid line took place
it has been impossible to determine, but it is significant that the
most nautiloid form of the Ammonitide, the Goniatites, appeared
after the Nautilide had attained their maximum development, and
some time after the genus Nautilus had itself appeared. Sutner
estimates that there are in the neighbourhood of four thousand
species belonging to the group of the ammonoids, nearly all of
which have the foliated sutures characteristic of the true ammo-
nites. With the exception of the genera Goniatites and Clymenia,
and the primitive ammonitic forms of the Carboniferous rocks
already referred to (Sageceras, Arcestes, Xenodiscus, Medlicottia,
Cyclolobus *), and a single form which occurs in the lowest member
of the Californian Tertiaries (the Tejon group), all the species are
restricted to the Mesozoic deposits, which by their great numerical
development they might be said to characterise. Probably no other
group of invertebrates exhibits such a remarkable series of devel-
opments corresponding with successive periods of time as do the
Ammonitide, and in none do the species appear to be so distinc-
tively characteristic of certain horizons (zones of ammonites). The
singularly diversified types of the Triassic period, which combine
all the various sutural modification seen in the goniatitic stage
(Sageceras, Lobites), the ceratitic (Tyrolites, Celtites), and the
ammonitic, from the simplest to the most complex (Pinacoceras),
are almost wholly wanting in the Lias, where an entirely new series
of forms begins (4igoceras, Harpoceras, Amaltheus). These in turn
are succeeded by groups more or less distinctive of the different
Jurassic zones (Oppelia, Stephanoceras, Lytoceras, Phylloceras),
which in the main die out before the close of the period. Most of
the Cretaceous forms belong to genera or sub-genera which have not
hitherto been represented, and here for the first time do we find any
great development of the remarkable groups of uncoiled ammonites
—Scaphites, Hamites, Turrilites, Crioceras, Ancyloceras (also Juras-
sic), and Baculites—whose advent seems to be foreshadowed by the

* Cyclolobus has the typical ammonitic sutures.

268 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Triassic genera Choristoceras, Cochloceras, Rhabdoceras, &c., which,
in their departure from the normal ammonitic type, resemble some
of these forms, but which differ in the simple character of the sutural
foliation. Considering the Ammonoidea to be the modified de-
scendants of the Nautiloidea, we have presented the somewhat
anomalous fact that while at the beginning of their existence in-
volution was the order of development, towards the end this develop-
ment was marked by a contrary evolution, with an accompanying
approximation in outline to that of the primitive type-forms. No
facts with which we are at present acquainted permit us to state
what was the underlying principle involved in these reversed
changes. It can merely be said that, involution having once set
in, any broad departure from the type newly attained must almost
necessarily have been accompanied by a certain amount of evolu-
tion.

The persistence of type-structure among the Nautiloidea, and
the relation which the geographical distribution of the Ammonoidea
bear to supposed climatic zones, have already been discussed in
previous sections. Still more involved in doubt than that of the
Ammonoidea is the ancestry of the Belemnitide, which, as the earli-
est representatives of the two-gilled order of cuttle-fishes, first appear
in the Trias, and practically disappear with the close of the Meso-
zoic era, one species only, and that somewhat doubtfui—Belem-
nites senescens, from Australia—being reported to pass beyond the
boundaries of the Cretaceous period.* That the group, however,
represents the ancestral line whence the recent Sepiophora (Sepia)
have been derived there can be but little question, seeing how close
is the relationship between the determining parts—internal skeleton
—of the fossil and living species. In the Eocene genus Belosepia
the phragmocone is of a somewhat transitional character. The
modern pen-bearing cuttle-fishes or calamaries (Chondrophora) ap-
pear to have their direct ancestors in the various forms of Teuthide,
whose remains, in a more or less perfect state of preservation, occur
in the Liassic and Oolitic deposits.

Of the two other classes of Cephalophora, the Gasteropoda and
Pteropoda, only the former acquire any geological importance.
Beginning with a comparatively limited number of forms in the

* The reference of this form to the Belemnitide is considered more than
doubtful by Branco (‘+ Zeitschrift d. deutsch. geol. Gesellschatt,”’ 1885).

GEOLOGICAL DISTRIBUTION OF GASTEROPODA. 269

Cambrian period, they steadily increase in number, until at the
present day the number of known species is far in excess of that
recorded from any other period of geological time. According to
the estimates made by Bronn between the years 1862 and 1866,
which may possibly still serve as a basis for the computation of
successive ratios, although no longer abreast of the times, the
numerical distribution for the several geological eras is as follows:

Paleozoic. Mesozoic. Cainozoie. Recent.
~ |No. of species. No. of species. No. of species.| No. of species.

DCaphoOpodys «:.a0 65. - «1 22 48 55 50
Prosobranchiata........ 73 1,764 4,622 7,500
Ileteropoda (inclusive of

the Bellerophontide). . 141 3 1 54
Opisthobranchiata....... 1 152 185 825
mtkmonatas™ 2 sacle 6 <i 530 5,700

With very few exceptions (Dentalium, Pleurotomaria, Capulus,
Natica, Narica, Emarginula) all the Paleozoic genera are extinct,
or at least generally considered to be so, and it is still question-
able whether they include even a single siphonate form. The refer-
ence of Fusus, Pyrula, and a few other members of the Siphonata
to this period, probably rests on unsatisfactory determinations, al-
though, indeed, no special reasons can be assigned for the non-
extension back of such genera. The absence of prominent characters
in many of the species renders their determination difficult or im-
possible, and it is by no means improbable that a fair proportion
of the genera which have received distinct names are in reality
identical with modern genera otherwise designated. The generally
holostomate character of the Paleozoic Gasteropoda imparts to the
fauna a peculiarity which eminently serves to distinguish it from
the similar fauna of the later Mesozoic and Tertiary eras, especially
the latter, where the Siphonata largely preponderate. The dominant
Paleozoic genera are Pleurotomaria, Murchisonia, Euomphalus, and
Loxonema, whose special development throughout the greater part

* The Pulmonata are now known to be represented by a limited number
of species in the Devonian and Carboniferous deposits. The number of

Paleozoic species indicated by Bigsby (1868-’78) is about treble the figure
given by Bronn.

270 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

of the Paleozoic series tends to link the different members to-
gether.

The earliest great differentiation in the ancient gasteropod fauna
is seen in the Jurassic deposits, where a host of new forms, especially
of the Siphonata (of the families Cerithiide, Nerineide, Apor-
rhaide, Strombid, Buccinide, Purpuride, Columbellide, &c.),
are for the first time introduced. One or two of these families
appear to have had their representatives already in the Trias, but
they were there of insignificant import. It is not, however, until the
Cretaceous period that many of the more distinctive of the modern
families (Cypreide, Cassidide, Ficulide, Tritonide, Muricide,
Volutidx, Olivide, Cancellaride, Terebride, Pleurotomide, and
Conidee) appear, and of these a fair proportion of the genera date
back only to the Eocene period. No recent species is recognised
as extending back beyond the Tertiary series, and even in the
Eocene the proportion of living to extinct forms is very slight,
averaging not more than three to five per cent. ; indeed, it is ques-
tionable whether any of the early Tertiary species can be identified
with recent forms. The same is also possibly true of the Oligocene,
but in the Miocene the percentage ranges as high as thirty-five,
and in the Pliocene to seventy-five or more. Practically, all the
Post-Pliocene forms are still living. It is impossible to arrive at
any absolute estimate of the number of species occuiring in each
formation. Bigsby °’ enumerates some seven hundred to eight hun-
dred species as belonging to each of the Silurian, Devonian, and
Carboniferous periods, or very nearly that which is given by Zittel °°
for the Jurassic forms; the Permian, which is deficient in nearly
all forms of life, has but about thirty. The Eocene-Oligocene
Paris basin contains, according to Deshayes, upwards of eighteen
hundred species, or more than double the number of the entire
Eocene shell fauna of the Eastern and Southern United States.
The Miocene basin of Vienna holds upwards of four hundred species
of Prosobranchiata.

There are but very few truly cosmopolitan species of fossil
Gasteropoda, although broad distribution was much more marked
in the early periods of the earth’s history than now. Thus, while
from the American Tertiaries only a very insignificant number of
forms could be selected which might in any way be correlated
with contemporary European species, and but a fairly representative

GEOLOGICAL DISTRIBUTION OF LAMELLIBRANCHIATA. 271

series from the Cretaceous, no less than two hundred and fifty out
of a round six hundred from the Silurian deposits are stated to occur
in Northern and Western Europe. Some seventeen or more species
out of the fifty-two recorded by Etheridge from the middle and
upper Paleozoic divisions of Australia find their analogues in the
equivalent deposits of Europe, and not unlikely this identity will
be increased on further comparisons being made. The Tertiary
species of the two regions, on the other hand, are almost without
exception distinct, and of the recent forms it may be doubted
whether there is a single species held in common.

The geological distribution of the Lamellibranchiata may be
considered to run parallel with that of the Gasteropoda, and in a
general way to partake of its peculiarities. Most regions are en-
tirely deficient in Cambrian forms, and even in the Lower Silurian
formations the number of species is rather limited. Barrande enu-
merates upwards of eleven hundred species from the Upper Silurian
formation of Bohemia alone, nearly double the number (636) that
was assigned by Bigsby in 1868 for the Silurian deposits of the
world generally, and considerably over that (918) which was claimed
by Bronn in 1862 for the entire Paleozoic series. The oldest forms
—i. e., Silurian and Devonian—belong almost exclusively to the
Heteromyaria (Aviculidw, Mytilide) and the Dimyaria (Nuculide,
Arcadsx, Astartide, Cardiide), although many of the Devonian
forms that have been referred to the Heteromyaria may really be-
long to the Monomyaria. The Sinupalliata among the Siphonida
appear to be completely wanting, as they are likewise from the
Carboniferous deposits, but it is by no means unlikely that some
of the commoner genera, as Grammysia, Allorisma, Sanguinolites,
Edmondia, &¢c., in which no sinual impression has been detected,
are true members of families whose modern representatives are all
furnished with retractile siphons. This supposition, which is based
upon external resemblances and habits as deduced from the shell,
is in full consonance with the theory of evolution, which would
lead us to suppose that the direct ancestors of the Sinupalliata were
closely resembling forms devoid of a sinual inflection. The refer-
ence of the forms above mentioned to the family Pholadomyidx
may, however, still be considered uncertain.

The Carboniferous Lamellibranchiata do not differ very broadly
from those of the preceding (Devonian) period, except in so far as

272 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

pertains to the first considerable development of the Monomyaria
(Pectinide, Limidz). Here, too, if we except the still problemati-
cal Preostrea, we meet with the earliest indubitable remains of
the oyster (Ostrea). As in the case of the Gasteropoda and Brachio-
poda, the number of Permian species is very limited. The lamelli-
branch fauna of the lower anil middle divisions of the Mesozoic
series, Trias and Jura, is characterised by a remarkable develop-
ment of the families Ostreide, Pectinids, and Limidsw among the
monomyarians, the Mytilide and Pinnidee among the heteromyarians,
the Arcadee among the Asiphonida, and the Astartide, Lucinide,
and Cardiide among the integropalliate Siphonida. The Phola-
domyide are especially abundant in the Jurassic deposits. Of the
two most distinctive Cretaceous groups, the Chamide and the
Rudistz, only the former have their Jurassic representative (Dice-
ras). Beyond the great specialisation of those two families, the
Cretaceous fauna does not differ essentially from the Jurassic, al-
though the number of true sinupalliate forms (Venerid, Tellinide,
Solenidx, Glycimeridz) is very much greater.

Through the different divisions of the Tertiary, beginning with
the Eocene, we see the gradual development which by almost im-
perceptible stages leads up to the fauna of the present day. The
Monomyaria, which in the Mesozoic period constitute nearly thirty
per cent. of the entire lamellibranch fauna, enter upon their decline,
and are succeeded, as well as the Heteromyaria, by the Dimyaria,
of both the sinuate and non-sinuate types. The relation of extinct
to recent forms in the different divisions of the Tertiary holds much
the same as with the Gasteropoda.

CRUSTACEA GENERALLY.

Of the recent orders of Crustacea the only ones that acquire
any geological significance are the Phyllopoda, Ostracoda, and
Decapoda, although representatives of some of the other orders
occur sparingly in formations extending as far back as the Devo-
nian period (Prearcturus, among the isopods [?]), and possibly
even to the Silurian (Necrogammarus, amphipod). It is a rather
surprising fact that of the first two orders, if we except one or
two special types—Leperditia, Beyrichia—all the most abundantly
represented genera of the earliest periods, as well as of the periods
succeeding, are such as still hold considerable prominence at the

DISTRIBUTION OF CRUSTACEA. 273

present day—Estheria, Cythere, Bairdia, Cypridina—thus present-
ing one of the most remarkable instances of the persistence of
type-structure known in the whole range of the animal kingdom.
The genus Estheria dates from the Devonian period, and attains
its maximum development in the Trias. In its modern distribu-
tion it may be said to be almost cosmopolitan, although it would
seem to prefer the regions of warm climate, and not to penetrate
much beyond the fifty-fifth parallel of latitude. The range of some
of the species is extraordinary. Estheria Dahalacensis, which oc-
curs as far north as Vienna, is found from Sicily to the island of
Dhalak, in the Red Sea, or over an area whose extent is meas-
ured by about thirty degrees of longitude, and thirty-two degrees
of latitude. The range of E. tetracera comprises fully forty de-
grees of longitude (Oran—Kharkov), but is more than equalled
by the Carboniferous species E. Leidyi, which has been reported
from both England and the State of Pennsylvania. It is a singular
circumstance that while all the recent species of Estheria are in-
habitants of fresh water, or of water which is but barely brackish,
the fossil forms are frequently, or generally, found associated with
distinctively marine types of organisms, indicating apparently for
these species also a marine habit. While this may have been
true, the association with fresh-water forms, which also occurs,
tends to show that it was only partially the case.

Possibly belonging to the order of the Phyllopoda, but by
some authors placed among the Malacostraca, are the singular
shield - bearing crustaceans of the Silurian period, Ceratiocaris,
Dictyocaris, Discinocaris, Peltocaris, &c., whose affinities have been
placed with the modern genera Nebalia (marine) and Apus (fresh-
water). In Discinocaris the shield in some individuals measures as
much as six inches across. Hymenocaris, which is exclusively
Cambrian, represents the oldest type of this order of crustaceans.
The genus Apus itself, which is almost universally distributed, and
has been observed even in Norway at an elevation exceeding three
thousand feet, appears as early as the Carboniferous period. Bran-
chipus, although devoid of a head-shield, is stated by Woodward
to be preserved as a fossil in the Eocene (Oligocene ?) beds of the
Isle of Wight.*? :

Of the more important genera of recent Ostracoda, Cythere and
Bairdia both date from the Silurian period, and Cypridina from

274 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

the Devonian; the fresh-water genus Cypris is unknown prior to
the Carboniferous. The species of the first two genera, whose dis-
tribution is almost universal, are particularly numerous in the Creta-
ceous and Tertiary deposits, and present some remarkable instances
of reputed longevity. Two recent species of Bairdia, B. sub-
deltoides and B. angusta, are claimed by Gerstaecker? to be
found also in the Carboniferous deposits, but it is by no means
improbable that the identification rests on improper determinations.
This is rendered the more likely, seeing how very few, compara-
tively, are the recent forms that have been identified as occurring
in the Tertiary deposits. Of some seventy species or varieties of
Entomostraca described by Rupert Jones from the British Tertiary
deposits from the Eocene to the Pliocene inclusive, not more than
seventeen or eighteen are recognised by him as constituting a part
of the recent fauna. A re-examination of the forms may possibly
increase this number somewhat, but it is certainly very remarkable
that of two hundred and twenty or more species of Ostracoda
dredged by the officers of the ‘‘ Challenger” expedition only three
or four had previously been described by paleontologists. While
many of the modern species have a broad distribution, the number
of forms which are known to be in any way cosmopolitan is ex-
ceedingly limited (species of Halocypris and Cythere). On the other
hand, there are some very marked instances of antipodal reappear-
ance. Several well-known British and northern forms have been
identified from Kerguelen Island and other remote regions of the
earth’s surface. Although apparently penetrating to the profound-
est depths of the sea, the number of both species and individuals
rapidly diminishes beyond a comparatively shallow superficial zone.
Only fifty-two species were obtained by the ‘‘ Challenger” from
a depth exceeding five hundred fathoms, and but nineteen from
below fifteen hundred. The much greater diversity of the shore
fauna as compared with that of the open sea is shown by the fact
that among the ‘‘ Challenger” Ostracoda only twenty-eight genera
were represented, whereas on the British coast alone there are at
least thirty-one. Among the oldest known representatives of the
order are the Primitia prima and Leperditia Cambrensis, from the
St. David’s (Lower Cambrian) rocks of Wales.

The remains of decapod crustaceans in the Paleozoic rocks are
exceedingly scanty, as indeed they are also in the earlier part of

DISTRIBUTION OF CRUSTACEA. 275

the Mesozoic formations. In North America they have been traced
back to the Devonian period (Palezeopaleemon ;—Macrura), but in
the European deposits they are not known befcre the Carbonifer-
ous age (Brachypyge ;—Brachyura ?). Whether the astaciform crus-
tacean found in the mountain limestone of Ireland, and described as
Astacus Philippi, was of a fresh-water habit, may still be considered
as more than doubtful. The same doubt extends to the various As-
tacomorpha of the Middle Mesozoic period—Eryma, Pseudastacus—
and not until we reach the chalk of Westphalia do we meet with
any undoubted remains of the genus Astacus itself. But even here
the deposit in which the remains are imbedded is of a marine facies,
and seems to argue that up to this time the crayfishes were by
nature inhabitants of salt water. Too much weight cannot, how-
ever, be attached to the negative evidence afforded by the absence
of known fresh-water forms of this group, inesmuch as the chances
for their preservation in deposits of this kind among the older
rocks is very slim. At the same time, it is not a little singular that
the extensive deposits of this nature of Wealden age should be en-
tirely barren of their remains. In the Tertiary deposits indispv-
tably fresh-water forms are met with, and it is not unlikely that the
full differentiation of these types from those of a marine habit was
effected somewhere about the close of the Mesozoic era. The
lobster or homarine type has probably its oldest representative in
the genus Hoploparia, which occurs in the Cretaceous and older
Tertiary deposits. Of the modern genera of prawns, Peneus ap-
pears to extend back to the Lias, and Palemon to the Tertiary
period.

The most important order of Crustacea, considered from the
geological standpoint, is that of the Trilobita, which, apart from
the simple fact of numerical development, acquires special signifi-
cance from the circumstance of its representing the earliest animal
group which attained to any prominence in geological history, al-
though in point of actual appearance it would seem to have been
preceded by the Brachiopoda and Annelida. Thus, from the basal
portion of the St. David’s beds of South Wales, which represent
the oldest or very nearly the oldest of the fossiliferous rocks that
have been thus far discovered, no trilobites are known, and it is
not until a full thousand feet in the same series of deposits is
passed that their remains are first met with. The number of

276 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

species of trilobites found in the inferior division of the Lower
Cambrian of Britain (the Longmynd and Harlech groups) is about
ten, representing six genera— Agnostus, Conocoryphe, Paradox-
ides, Microdiscus, Paleopyge, Plutonia—and of the entire Cam-
brian series one hundred, distributed as follows :

Upper Tremadoc...... 12 (including 2 from the Upper Lingula).
Lower Tremadoc...... 19.

Upper. Lingula, ¢...... BO Cae 5 ‘¢ Lower Lingula).
Lower Lingula........ el Oe 14 ‘¢ Menevian).
Menevaaninaney sacar SO e: ges 4 es Longmynd).

Longmynd and Harlech 10.

From the Primordial zone of Bohemia (Cambrian) Barrande
recognised in 1871 only twenty-seven species, or but little more
than one-tenth the number (252) which he claimed for the Cam-
brian deposits of the world generally. This paucity, as compared
with the richness of the British fauna, is the more surprising when
we consider how largely in excess of the insular forms are the Silu-
rian species from the same region. The Bohemian basin contained
at the period stated about three hundred and twenty species,
whereas the total number of species recognised at about the same
time from the entire British Paleozoic series of deposits—i. e., from
the Cambrian to Carboniferous inclusive—only slightly exceeded
two hundred and twenty.

Of the seventeen hundred species, representing seventy-five
genera, tabulated by Barrande for the world at large we find
(using his data) two hundred and fifty-two relegated to the Cam-
brian formations, eight hundred and sixty-six to the Lower Si-
lurian, four hundred and eighty-two to the Upper Silurian, one
hundred and five to the Devonian, fifteen to the Carboniferous,
and one to the Permian.* While these figures would indicate a
pronounced culmination of the group in the Lower Silurian period,

* The number of species has been very materially increased since the
publication of Barrande’s paper, but his estimates will still serve as a preper
basis for the computation of ratios. The American Carboniferous species
seem to fall not far short of a dozen by themselves, Considerable uncer-
tainty still attaches to the stratigraphy of the forms that have been referred
to the Permian of Germany and the United States (Guadalupe Mountains, in

Texas and New Mexico), and it is generally assumed that there are no Per-
mian species at all.

DISTRIBUTION OF TRILOBITES. 277

it is a significant fact that in Bohemia, which stands next to Scan-
dinavia in respect of number of species, the numerical ratio of
Lower Silurian to Upper Silurian forms is as one hundred and
eighteen to two hundred and five, reversing, apparently, the order
of development. ;

The very limited number of generic forms that pass from one
major formation to another is remarkable. Barrande enumerates
but seven of the twenty-seven Cambrian genera which pass over
into the Silurian, and twelve of the fifty-five Silurian genera which
reappear in the Devonian. The Carboniferous genera are but three
or four in number (Phillipsia, Griffithides, Brachymetopus, Proe-
tus).* Of the fifty-five Silurian genera, with three exceptions, all
the forms are already represented in the lower division. The
number of genera that extend through two or more formations is
reduced to two or three (Phillipsia, Proetus). In their geographi-
cal relations it may be said that broad distribution is the rule
rather than the exception. Thus, of the forty-two genera of the
Bohemian basin thirty are held in common with Sweden, and twenty-
four with England. More than one-half (seventeen out of thirty)
of the North American genera are also trans-Atlantic forms, and
the greater number of these are widely distributed over the Euro-
pean continent. It has generally been considered that the most
widely distributed genera are those which also have the greatest
vertical range; but the exceptions to this supposed rule are so
numerous—Paradoxides, Agnostus, Trinucleus, Asaphus—that it
may be doubted whether any value is to be attached to it. Nor
can it be maintained that in all cases the genera having the longest
range are those which have the greatest number of specific repre-
sentatives, although this is more often the case than otherwise.
Probably the greatest number of species represented in any one
genus is exemplified in the case of the genus Dalmanites (Lower
Silurian-Upper Devonian), of which there were up to 1871 some
one hundred and twenty-nine known. The nearest approach to
this (some one hundred and fifteen or more) is seen in the genus
Asaphus, which is restricted to the Lower Silurian formation.

The number of species that transgress the boundaries of any
major formation is exceedingly limited. Thus, it is very doubtful

* Professor Claypole has more recently described a species of Dalmanites
(Dalmania) from the Waverly Group (Sub-Carboniferous) of the United States.

278 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

whether there is even a single species from the Cambrian which
also forms part of the Silurian fauna. There are apparently but
three forms—Calymene Blumenbachii, Dalmanites caudatus, Sphe-
rexochus mirus—which in England connect the Lower and Upper
Silurian faunas, and an equally small number which unite the
Silurian with the Devonian. In Bohemia the number of Lower
and Upper Silurian connecting-forms is somewhat larger; but even
here the proportion to the entire fauna—nine out of three hundred
and twenty-three—is very small. The limitation in most cases is
even more pronounced, fixing the species to definite horizons of the
broader formations.

With respect to horizontal specific distribution, instances of broad
dispersion are not exactly uncommon. A fair proportion of the
Bohemian species, for example, are spread throughout Sweden,
Italy, Russia, and England, and a number have also been indicated
as occurring in the equivalent deposits of the North American con-
tinent. Calymene Blumenbachii is the commonest form occurring
on both sides of the Atlantic, in both regions being alike a Silurian
and Devonian species.

Coincidently with the decline of the Trilobita we note the ap-
pearance of crustacean forms (Eurypterida) which hold a some-
what intermediate position between these and the modern king-crab
(Limulus), whose remains are first met with in rocks of Jurassic
age. Of this singular order, which comprises the giants of the
class, some half-dozen or more genera are recognised, whose com-
bined range includes the Upper Silurian and Carboniferous deposits.
In the Ludlow (U. Silurian) rocks of Britain there are no less than
thirty-two species of this order, representing six genera—Eurypter-
us, Pterygotus, Himantopterus, Slimonia, Stylonurus, and Hemi-
aspis, the last a transitional type connecting the group with the
Carboniferous limuloid forms constituting the family Bellinuride
(Bellinurus, Prestwichia, Euproéps). The most ponderous indi-
viduals of the order (Pterygotus Anglicus, Slimonia Scoticus), which
are at the same time the largest of all known Crustacea, recent or
fossil, measuring from five to six feet in length, do not appear
until the Devonian period, or not until the group had attained to
considerable development. The simultaneous appearance among
the trilobites of the largest and smallest forms — Paradoxides,
Agnostus—would seem to point to a contrary order of develop-

DISTRIBUTION OF INSECTS. 279

ment, but there can be no question that the first appearance of
these animals long anteceded the Cambrian period. The total
number of eurypteroid forms occurring in the American deposits
is twenty-three (representing the genera Eurypterus, Dolichopterus,
Pterygotus, and Stylonurus), six of which (Eurypteri) are Car-
boniferous, two Devonian, and the remainder Upper Silurian.’
The oldest known limuloid form is the Neolimulus falcatus, from
the Upper Silurian rocks of Lanarkshire, whose early appearance
would seem to indicate that while the family to which it belongs
(Bellinurida) may stand in its relations intermediately between the
eurypterids and the king crabs, its actual origination may be
traceable, at least in part, to direct modification from the trilo-
bitic type.
INSECTS.

The number of recognised species of insects is generally con-
ceded to be upwards of 100,000, and by some authors is placed as
high as 150,000, but it is very questionable whether these represent
more than one-tenth of the number actually inhabiting the earth’s
surface. Probably not less than one-half of the indicated forms
belong to the order Coleoptera, or beetles, which is by far the most
numerously represented of all the orders. The Lepidoptera, or but-
terflies, have thus far yielded some 15,000 species—or about one-
thirteenth of the total number (200,000) estimated by Speyer for
the world at large—and an equal number may, perhaps, with a cer-
tain amount of accuracy, be credited to the Hymenoptera (bees,
wasps, and ants), the Hemiptera (bugs), and Diptera (flies). The
Orthoptera, or straight-winged insects, which include the locusts,
grasshoppers, &c., are considerably less numerous, while the spe-
cies of netted-veined forms (Neuroptera) probably do not much ex-
ceed 2,000, or perhaps do not even reach this figure.

Our knowledge of the general insect fauna of the globe is still
too limited to allow of any satisfactory conclusion being drawn as
to the geographical distribution of the class as a whole ; enough
is known, however, to permit it being stated that practically every
portion of the earth’s surface harbours a more or less extensive
insect fauna, so that the distribution of this class of animals may
be said to be universal. While most numerously developed in
the warmer or tropical areas, insects are by no means rare in the
region of high latitudes, and, indeed, in some of the most north-

280 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

erly points reached by man they appear to be still remarkably
abundant. The officers of the British North Pole Expedition,
under command of Sir George Nares, brought home a surpris-
ingly rich fauna from the region (Grinnell Land) lying between
the seventy-eighth and eighty-third parallels of latitude, com-
prising no less than forty-five species of true insects and sixteen
arachnids, the former distributed as follows: Hymenoptera, five
species (two humble-bees); Coleoptera, one; Lepidoptera, thirteen;
Diptera, fifteen; Hemiptera, one; Mallophaga, seven; and Collem-
bola, three.*? Among the Lepidoptera are a number of forms
belonging to genera common in the temperate zones, such as Co-
lias, Argynnis, Lyczna, &c., which appear the more remarkable,
seeing that the species of this order are more limited in Green-
land (with an insect fauna numbering eighty species), and that no
forms are met with either in Iceland or Spitzbergen, although up-
wards of three hundred species of insects are represented in the
former. On the other hand, M. Bonpland observed butterflies on
the slopes of Chimborazo at an elevation of 16,626 feet, or but
1,600 feet below the highest level (18,225 feet) reached by insects
(Diptera), as observed by Humboldt, on the same mountain.

Insect life flourishes also to a certain extent in waters of high
temperature (hot springs); and even on the free surface of the ocean,
most distantly removed from land, the officers of the ‘‘ Challenger”
circumnavigating expedition everywhere obtained one or more spe-
cies of Halobates, a member of the Hemiptera, which is stated to
live entirely at sea, and to carry its eggs about with it attached to
its body.

The distribution of insects is determined largely by climatic and
general physiographical conditions, and also to a great extent by
the nature of the food-supply, many forms, as has already been
seen, being dependent for their sustenance (whether in the larval
or mature state) upon the development of a particular vegetable
product. Indeed, localisation or restriction appears to be more
frequently brought about as the result of changes in the character
of the vegetation than as a condition depending upon the interpo-
sition of physical barriers which, through their powers of flight,
the animals of this class are in great measure able to overcome.
The effect of climate is, however, well marked, and is seen in the
general restriction of numerous forms to particular climatic zones.

DISTRIBUTION OF INSECTS. 281

An extended meridional extension is more frequently to be observed
among the tropicopolitan forms than among those which more
properly belong to the temperate regions ; and this is especially
the case among African insects, where frequently the same spe-
cies is found to inhabit both the northern and southern parts of
the continent. This condition is also to be observed in the case of
northern forms, when mountain-chains, trending in a meridional -
direction, permit of easy access to regions of very varying physio-
graphical features, which in their more elevated parts present
conditions more nearly uniform with those exhibited elsewhere on
the lowlands. Thus, we find in the Chilian fauna numerous forms
that more properly belong to the north temperate zone—the pre-
ponderating element among the Carabidae, for example, and the
genera Lycena, Colias, and Argynnis among the butterflies. These
not improbably found their way southwards in successive migra-
tions along the Andean mountain-system, where suitable habita-
tions, corresponding in general physiographical features to those
of their northern home, could readily be found. A broad horizon-
tal or latitudinal distribution, per contra, characterises the insect
fauna of the north temperate zone. A large proportion of the
European species, for example, are spread over the far interior of
the Asiatic continent, and, indeed, many of them reappear in
America. Nothing more strikingly illustrates this broad diffusion
of species than the case of the Japanese lepidopterous fauna, which,
out of some 1,110 species of Macro-Lepidoptera, contains, accord-
ing to Pryer,’”* not less than 123 species that are common to Great
Britain, or about 16 per cent. of the entire British fauna.

Some remarkable and not wholly comprehensible anomalies of
distribution are exhibited by the faunas of almost every region,
which render unusually intricate the general problems of distribu-
tion presented by the class as a whole. One of the most interest-
ing and instructive of these is the special relationship which unites
the New Zealand and Chilian and Patagonian coleopterous faunas,
and the distinctness of the fauna of the first-named region from the
Australian,’ a condition which, as Professor Hutton has shown,
also characterises some of the other animal groups, and which
would seem to argue in favour of some former direct land connection
(trans-Pacific) between New Zealand and a portion of the South
American continent.

282 GEOGRAPIIICAL AND GEOLOGICAL DISTRIBUTION.

The remains of insects in the older Paleozoic rocks are very
scanty, and in the main they occur in such an unsatisfactory state
of preservation as to have led to the most divergent views respect-
ing their true relationship. The most ancient of these forms, and
the only one that is thus far known from the Silurian rocks, is the
Paleoblattina Douvillei, recently described by Brongniart from the
Middle Silurian sandstones of Calvados, France, and referred by
that naturalist to the orthopteroid group of the cockroaches. No
other member of the orthopterous division of insects is positively
known prior to the Carboniferous period, and it is not unlikely that
the fossil in question, which is represented by a single impression of
a wing, may on further investigation prove to belong to the group
of netted-veins (Neuroptera or Pseudo-Neuroptera), which alone
among the different orders has representatives in the Devonian
rocks. These last comprise fragments representing some five or
six species, belonging to possibly as many genera—Palephemera,
Gerephemera, Lithentomum, Homothetus, Xenoneura, and Dis-
crytus. The first two are referred by Hagen to the modern type of
the Libellulz (Pseudo-Neuroptera), and the remaining three, not
counting the very doubtful and fragmentary Discrytus, to the like-
wise modern sialine tribe of the Neuroptera. By Mr. Scudder, on
the other hand, several of these earlier hexapods are considered to
represent synthetic types, and have accordingly been referred to
families specially created for their reception—Palephemeridex, Ho-
mothetide, Xenoneuride ; indeed, the same authority, following
in the footsteps of Goldenberg and Brongniart, insists that these
forms, as well as all others, with possibly one exception, from the
Paleozoic deposits, in a given departure from modern type-struc-
tures, and in the possession of combination ordinal characters, con-
stitute a special group or order apart by itself, the Palzeodictyoptera,
whose diverging specialisation (effected at about the beginning of
the Mesozoic era) outlined the various higher groups or orders now
recognised by entomologists.7® In conformity with this view the
Paleozoic insect was a synthetic hexapod, in which ordinal differ-
entiation had not yet asserted itself. The Carboniferous cock-
roaches (Palroblattarie), which constitute probably one-half of
the entire Paleozoic insect fauna, and of which some sixty or more
species are known, and the contemporaneous walking - sticks—
Protophasma, the giant Titanophasma from Commentry, France,

DISTRIBUTION OF INSECTS. 283

&c.—are accordingly not true Orthoptera, but orthopteroid Paleo-
dictyoptera; the Carboniferous and Devonian netted-veins not true
Neuroptera or Pseudo-Neuroptera, but neuropteroid Palzodictyop-
tera, and, similarly, the Hemiptera (Eugereon, Fulgorina), hemipte-
roid Paleodictyoptera. Apart from the contradictory conclusions
which have been reached from the study of these forms by Hagen,
Gerstaecker, Eaton, and others, it may be reasonably doubted
whether the extreme specialisation seen among the Paleodictyoptera
will carry out the inference that the larger groups of Paleozoic times
were more closely related to one another ‘‘than any one of them
is to that modern group to which it is most allied, and of which it
was with little doubt the precursor or ancestral type.” *°* Surely,
it will not be contended that Palephemera and the highly special-
ised Titanophasma are more nearly related to each other than they
are to the modern families Libellulide and Phasmide, not to men-
tion the orders to which these belong ; and if this be so, why
should they be referred rather to the one loose comprehensive group
than to the several groups which they immediately represent ?

The remains of beetles (Coleoptera), if we except the very
doubtful Troxites (which is considered by some naturalists to
represent the fruit of a plant), are unknown in the Paleozoic depos-
its; but it is by no means unlikely that the members of this order
had already existed, since: borings in wood, very like those made
by the coleopteroid larva, have been discovered in various localities. *

The Triassic insect fauna, which is represented by some four or .
five European species, and by about twenty in America (Colorado),
is almost exclusively orthopteroid, and exhibits a distinct passage
between the ancient and modern types of cockroaches—Palzoblat-
tarie and Blattarie. The first indisputable beetle (Chrysomelites),
followed by several highly differentiated types in the Rhetic—
Hydrophilites, Buprestites, Curculionites—is found in the deposits
of this age. No truly metabolous insects, or those undergoing
complete metamorphosis, other than Coleoptera, are known before
the Lias, where, however, we have several species of Diptera
(Chironomide, Tipulidz), and at least one representative of the
Hymenoptera, an ant (Paleomyrmex prodomus), from Schambelen,
| * Different coleopteroid species have at various times been described from

‘Carboniferous strata, but these are now known to be mainly referable to the
Arachnida or spiders.

284 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Aargau. The same Swiss deposits have yielded upwards of one
hundred and ten species of Coleoptera, in addition to various forms
of Orthoptera, Neuroptera, and Hemiptera (Cicadina). A true
song-cricket (Cicada Murchisoni) has been described by Brodie
from the English Lias. The most diverse types of existing Neu-
roptera and Orthoptera, which appear to have been fully differ-
entiated at this period, acquire a further development in the suc-
ceeding Oolites, where, in addition to representatives of all the
other orders that had thus far appeared, we meet with the earliest
Lepidoptera (Sphingide). :

The singularly deficient fauna of the Cretaceous period is suc-
ceeded in the Tertiary, more particularly in the Oligocene and
Miocene divisions, by a most prolific development of specific forms.
The Miocene deposits of Switzerland, and the immediately ad-
joining tracts, have yielded to Dr. Heer no less than eight hun-
dred and seventy-six species—eight hundred and forty-four of
which are recorded from Oeningen (Baden) alone—distributed as
follows: Coleoptera, five hundred and forty-three; Orthoptera,
twenty; Neuroptera, twenty-nine; Hymenoptera, eighty-one; Lepi-
doptera, three; Diptera, sixty-four; and Rhynchota, one hundred
and thirty-six. Scarcely less famous as insect localities than Oen-
ingen are Aix in France and Radoboj in Croatia; but apparently far
surpassing either of these in respect to both individual and specific
development are the tufa-beds of the Florissant region in Colorado,
referred to the Oligocene period. The Hymenoptera from these
deposits comprise several species of bees (Apidae and Andrenide),
about thirty species of wasp-like forms (Vespide, Sphegide, &c.),
fifty species of ants (represented by about four thousand specimens,
mainly Formicid), and some eighty species of Ichneumonide, be-
sides numerous other forms. The Diptera individually make up
nearly one-third of all the specimens found in the region (Culicide,
Tipulide, Bibionide), and of the heteropterous division of the
Hemiptera there appear to be no less than one hundred species.
The Coleoptera are likewise exceedingly abundant, and comprise
amorg other forms some thirty species each of the families Carabide,
Staphylinide, and Scarabeide, and forty of the Elateride. The
total number of species represented in this order is about three
hundred, of which about one hundred and twenty belong to the
rhynchophorus division.

DISTRIBUTION OF ARACHNIDA. 285

Owing to the very limited nature of insect faunas in general,
and the circumstance that only a few localities have thus far
yielded insect remains in any abundance, it is impossible to draw
any positive conclusions respecting either the geographical dis-
tribution or the genealogy of the members of this class of animals.
It appears practically certain, however, that the metabolous types
were descended from the ametabolous, and that the larve of the ear-
lier forms were all, or mostly all, aquatic in habit. The geological
and horizontal range of the majority of the species appears to have
been very limited, but it must be recollected that in most instances
the number of individuals found representing any one given species
is altogether too small to permit of any logical inference being
drawn from their occurrence. Thus, of the numerous species of
Paleozoic cockroaches, by far the greater number are represented
by single specimens, or by specimens coming from a single locality.

ARACHNIDA AND MYRIAPODA.

The earliest arachnoid remains (scorpions) occur in the Upper
Silurian deposits of the island of Gothland, Sweden, and Lanark-
shire, Scotland, and in the Helderberg roeks of Waterville, New
York, from each of which regions a single specimen has been ob-
tained. The Swedish species, Paleeophoneus nuncius, with which
the Scotch form appears to have been nearly related, ranks among
the largest of its class, measuring about three and a half inches
in length ; in its general characters it closely approximates the
modern scorpions, although, as has been pointed out by Professor
Lindstrém, the structure of the large and pointed thoracic limbs
more nearly approaches what is seen in the embryonic forms of
other Tracheata and in Campodea. The presence of stigmata and
the whole organisation of the body clearly demonstrate the ani-
mal to have been an air-breather and an inhabitant of dry land.
The American form, Proscorpius Osborni, is less clearly recognisable
than the European, and some doubt has been thrown upon its
arachnoid nature, which is maintained by both Whitfield and Tho-
rell. Excepting these two or three earliest precursors of the Scor-
pionide, whose presence would naturally seem to indicate a rich
insect fauna for the period, no traces of arachnoid remains are known
antedating the Carboniferous deposits, where, however, several well-
marked genera, singularly close in their relationship to modern

286 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

forms, and representing spiders (Protolycosa, Architarbus, Anthra-
comartus), scorpions (Cyclopthalmus, Eoscorpius), and pseudo-scor-
pions (Microlabis), are met with. Inthe Mesozoic deposits but few
arachnoid remains, in most cases in an imperfect state of preserva-
tion, have thus far been discovered, and it is not until about the
middle of the Tertiary series, Oligocene, that they acquire by their
numbers any importance. The amber deposits of Europe and the
Florissant beds of Colorado have yielded the greatest abundance
of such remains.

It is not a little remarkable with what degree of persistence
the fundamental characters of scorpions have been preserved, for
it appears, as has been claimed by Mr. Peach, that the Car-
boniferous forms, as represented by Eoscorpius, were as highly or-
ganised and specialised towards the beginning of this period as
their descendants of the present day. The Paleozoic araneids, on
the other hand, appear to have been all, or in the main, possessed
of distinctly segmented abdomens, thereby forming a transitionary
group between the arthrogastric and non-arthrogastric arachnoids.

Both the chilognathous and chilopodous types of Myriapoda may
be said to be represented in the Carboniferous rocks, although from
certain peculiarities of structure possessed by these early forms—
the genera Euphoberia, Xylobius, Acantherpestes, Trichiulus, among
the former, and Palzocampa among the latter—which are un-
known in their modern representatives, special ordinal groups, the
Archipolypoda and Protosyngnatha respectively, have been created
for them. It may be doubted, however, whether such knowledge
as we possess of the animals in question will permit of the reten-
tion of these groups; indeed, it appears by no means certain that
all the forms referred here as Myriapoda are actually such at all.

The earliest myriapod remains, referred by Peach *’ to the Chilo-
gnatha, occur in the Old Red Sandstone (Devonian) of Forfarshire,
Scotland, and not improbably the problematical Gyrichnites of the
nearly equivalent deposit of Gaspé are the belongings of these
animals. The Mesozoic rocks are singularly deficient in their traces,
and may be said to be almost wholly wanting in them; excepting
the somewhat doubtful Geophilus proavus from the Jurassic deposits
it appears that no chilopodous form is met with before the Ter-
tiary.

Distribution of the Vertebrata.—Fishes.—Amphibians.—Reptiles.— Birds. —
Mammals.

FISHES.

TuE geographical distribution of fishes is at the present day,
and probably has been for a considerable number of past geologi-
cal periods, world-wide. Although vastly more abundant, if not
individually at least specifically, in the regions of elevated tem-
perature than in those of the opposite extreme, both as regards
the marine and fresh-water forms, they are still far from wanting
in waters of icy coldness, whether these be in high latitudes, the
oceanic abysses, or elevated mountain lakes or streams. The offi-
cers of the British Polar Expedition, under command of Sir George
Nares, obtained specimens of the charr (Salmo arcturus and §8.
Naresii) from beyond the eighty-second parallel of north latitude,
the highest point at which fresh-water fishes have been observed,
and from a still higher latitude, the eighty-third, some half-dozen
species of shore fishes, among them a bull-head and cod (Cottus
quadricornis, Gadus Fabricii, Icelus hamatus, Cyclopteris spinosus,
Liparis Fabricii, Gymnelis viridis).°* And were it not for the in-
superable obstacles that were interposed in the way of fishing, there
can be no doubt that many additional forms would have been dis-
covered. The number of forms that descend into, or inhabit, the
abyssal waters whose temperature is about that of freezing is very
considerable; Ginther* enumerates thirty-nine species whose
range extends to, or passes beyond, the fifteen hundred fathom
line, thus penetrating deep into the zone of icy coldness. In the
Eurcpean Alpine region fishes (salmonoids) inhabit the lakes or
streams situated at about the level of perpetual snow, and there is
very little doubt that the same is the case in nearly all regions of

288 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

elevated mountains. The loach has been found in the Himalayas
at an altitude of eleven thousand feet, and in the South American
Andes, Lake Titicaca, at an altitude of thirteen thousand feet,
has yielded several species. Indeed, in the latter region, some of
the Alpine cyprinodonts, as Trichomycterus, penetrate to heights
of fifteen thousand feet, and upwards.

Fresh-Water Fishes,—It will be evident from the present rela-
tion existing between land and water—which in its general features
unquestionably dates from a very remote geological period—and
the resulting barriers opposed to a free migration, that fresh-water
fishes will be much more limited in their range than the fishes of
an oceanic type, whose distribution is in main part governed by
conditions of food-supply and temperature, and to a certain extent
by the nature of oceanic currents. This comparative areal restric-
tion among fresh-water forms is exemplified not only in the case of
species and genera, but also in that of families, none of which, if
we except the cat-fishes (Siluridee), can be considered to be in any
way cosmopolitan. Manifestly, the oceanic basins must prove to
the animals of this class an obstruction much in the manner that
it does to the higher animals, the reptiles and mammals, for ex-
ample. Yet, certain peculiar occurrences would seem to indicate
that the natural barrier thus formed is not in all cases as effectual
in preventing the distribution of fishes as it is with the majority of
the animals just mentioned. Thus, several identical species, as the
salmon (Salmo salar), perch (Perea fluviatilis), burbot (Lota vul-
garis), pike (Esox lucius), and a stickleback (Gasterosteus pungitius),
inhabit alike the waters of Europe and Eastern North America;
the perch of the Ganges and other East Indian rivers (Lates cal-
carifer) is found in the waters of Queensland, Australia; and one
of the forms of south temperate so-called ‘‘ trout” (Galaxias atten-
uatus) inhabits Tasmania, New Zealand, the Falkland Islands, and
the southern extremity of the continent of South America. In
addition to such divided species, representing, naturally, divided
genera as well, there are also several generic types whose lim-
ited number of representatives (while distinct specifically) be-
long to opposite quarters of the globe. The genus Umbra, limited
to two species, is represented in the Atlantic States of the American
Union by the ‘‘dog” or ‘‘ mud fish” (U. limi), and in the Danubian
system of waters by the ‘‘Hundsfisch” (U. Krameri); the shovel-

DISTRIBUTION OF FRESH—WATER FISHES. 289

nose sturgeons (Scaphirhynchus), and the paddle-fishes (Polyodon-
tide), both of them restricted to some two or three species, are con-
fined respectively to the river systems of Central Asia and the Mis-
sissippi, and the Mississippi and the Yangtse-Kiang; the American
suckers (Catostomus) have an outlying representative in Siberia;
while the East Indian genus Symbranchus, after skipping ‘Africa,
reappears with a single species (8. marmoratus) in the waters of
South America.

In what precise manner these equivalent types have found their
way to such widely removed portions of the earth’s surface it has
been thus far impossible to determine. That some transference
was effected by way of northern waters over land-surfaces now no
longer existing is very nearly certain ; hence, the occurrence of
identical or representative specific forms in the streams of Northern
Eurasia and North America is not very surprising. But that a
similar transference was effected over the broader or equatorial
parts of the oceanic basins, a hypothesis necessitating the assump-
tion of the submergence of vast continental land-masses where no
traces of their former existence are visible, is more than doubtful.
At any rate, it is very unlikely that any such alternation in the
relative positions of land and water took place at a time so recent
as satisfactorily to explain such anomalies of distribution as are
presented by the genera Lates and Symbranchus, already men-
tioned, and by the genus Pimelodus (Africa and South America)
among the cat-fishes. It would appear at first sight far more
natural to assume that these fishes were originally of a marine
type, spread over the oceanic expanses, and that at a later period
they accommodated themselves to fresh-water conditions, and grad-
ually restricted their habitats to regions where we now find them.
This is not unlikely, seeing that some of these (Lates, Symbranchus)
freely enter brackish water. That such has been the recent origin
of many forms of fresh-water fishes is placed beyond question.
Several permanent species of the Northern Baltic, where, through
an excessive indraught of fresh water from the surrounding streams,
the water has lost most of its salinity, are identical with marine
types inhabiting the Arctic seas to the north. Yet the accommo-
dation to new conditions of existence was effected since the closing
off of the Baltic from the northern ocean, or since the Glacial
period. The gobies, blennies, and atherines of the northern lakes

290 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

of Italy present us with other instances of the permanent establish-
ment of marine types in fresh waters. Indeed, it is scarcely neces-
sary to seek for examples of this kind, seeing how very readily the
many marine fishes which periodically ascend the inland streams
during the spawning season accommodate themselves to the newly
imposed conditions. Of so little importance does a change of
medium appear to be in many cases that it is frequently very difli-
cult, or impossible, to indicate whether a given group of fishes is
more properly of a marine or fresh-water type. The numerous in-
stances where certain species of a genus are of one habit, and other
species of the same genus of the opposite habit, render the deter-
mination of this question still more difficult.

An accommodation similar to that which has been noticed in
the case of marine fishes also obtains with many of the more strictly
fresh-water forms; 7. e., they descend without inconvenience into
the briny oceanic medium. This we see in the case of the trout,
the charr, in several species of Coregonus, and especially among
the toothed carps (cyprinodonts) and sticklebacks. How far these
may wander out to sea is not exactly known, but there is no special
reason for supposing that they might not proceed, at least in some
instances, to very considerable distances. A species of the cyprino-
dont genus Fundulus (F. nigrofasciatus) was obtained by the offi-
cers of the ‘‘ Challenger” from the pelagic fauna of the Atlantic,
midway between St. Thomas and Teneriffe. It is manifest, there-
fore, that an.arm of the sea is not an impassable barrier to certain
forms of fresh-water fishes; and not impossibly some brackish-water
forms may occasionally find their way completely across the oceanic
expanse. The irregular distribution of certain types or species
thus receives a partial, or, at any rate, a possible solution.

The total number of species of strictly fresh-water fishes recog-
nised by Ginther is nearly two thousand three hundred, of which
four are lung-fishes, thirty-two ganoids, twelve lampreys, and the
remainder teleosts or bony-fishes. Of the last nearly one-third are
comprised in the family of the carps (Cyprinidae) and somewhat
more than one-fourth in that of the cat-fishes (Siluride). The
Characinide and Chromides, forms from tropical America and
Africa, are represented by somewhat more than two hundred and
fifty and one hundred species respectively, the salmonoids by one
hundred and thirty-five species, and the toothed carps (cyprino-

DISTRIBUTION OF FRESH—WATER FISHES. 291

donts) by one hundred and ten species. As to their geographical
distribution, two primary zones might be recognised: the northern,
corresponding largely to North America and Temperate Eurasia,
characterised by the presence of sturgeons, salmonoids, pikes, and
numerous carps, with only a feeble development of the cat-fishes ;
and the southern or tropical zone, comprising the Indian, Ethio-
pian, Neotropical, and Australian regions of zoogeographers, char-
acterised by a special development of the cat-fishes. The fol-
lowing scheme for the classification of the southern zone has been
proposed by Dr. Gunther:

Cyprinorp Diviston.—Characterised by presence of Cyprinide
and Labyrinthici.

1. Indian Region, 625 Species.—Characterised by Ophiocephalidze
and Mastacembelidz. Cobitoids numerous.

2. Africun Region, 255 Species.—Characterised by lung-fishes
(Protopterus) and ganoids (Polypterus, Calamoichthys). Chromoids
and characinoids numerous. Cobitoids absent.

Acyprrinorip Diviston.—Characterised by absence of Cyprinide
and Labyrinthici.

1. Tropical American Region, 672 Species.—Characterised by
lung-fishes (Lepidosiren). Chromoids and characinoids numerous.
Gymnotide (electric eels).

2. Tropical Pacific Region, 36 Species.—Characterised “sie lung-
fishes (Ceratodus Forsteri and C. miolepis, from the waters of
Queensland, Australia). Chromoids and characinoids absent.

The eastern and western divisions of the northern zone, with
some three hundred and sixty and three hundred and forty species
respectively, are very closely related to each other, not only through
the preponderance of types that are common to both regions, but
in the possession, as has already been seen, of a number of identical
species. Two genera of ganoids not found in Eurasia, Lepidosteus
and Amia, serve to characterise the American ichthyic fauna, which
is further distinguished from its trans-Atlantic correspondent in
the special development of the suckers (Catostomide) and in the
absence of cobitoids and barbels (Barbus).

An Antarctic zone, made to include New Zealand, Tasmania
(with a portion of Southeast Australia), the Falkland Islands, Tierra
del Fuego, Patagonia, and Chili, whose faunas are very intimately
related to one another, is recognised by some authors, but the num-

292 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

ber of species here represented is too limited to permit of much
importance being attached to a negative region of this kind.
Galaxias attenuatus, a species of southern ‘‘trout,” and one of the
three species of lamprey are found in New Zealand and the Tas-
manian and Fuegian tracts. No fresh-water fishes are thus far
known to inhabit any of the islands situated south of the fifty-fifth
parallel of south latitude.

The paucity of the fish-fauna of the tropical Pacific region is
very remarkable, and only receives a partial explanation through
the circumstance that the greater part of the tract belonging to it,
the Australian, is deficient in water-courses. The island of Celebes,
for example, which, as has been well urged by Ginther, would
seem to offer favourable conditions for the development of a fresh-
water fauna, has thus far offered barely more than a half-dozen
species, all of them common Indian forms; nor has New Guinea
shown itself to be much more prolific. Long-continued isolation
has apparently prevented much of the tract from receiving the
necessary supply from the fresh waters of continental areas, al-
though the identity of existing forms with such as are found else-
where would seem to indicate a recent migration and peopling of
the waters. The smaller islands of the Pacific are inhabited prin-
cipally by such forms, as eels, atherines, gobies, mullets, which
can readily exchange fresh water for salt water, and to which, con-
sequently, the oceanic basin constitutes no insuperable barrier to a
free migration. A species of Arius, a siluroid, inhabits the Sand-
wich Islands.

The marine fishes may be conveniently divided into three cate-
gories: shore fishes, or such as habitually frequent the coast-lines,
and which rarely descend to a greater depth of water than three
hundred fathoms; pelagic fishes, which inhabit the waters of the
open sea, the majority of them spawning there also; and deep-sea
fishes, or the fishes of the greater oceanic depths, where the in-
fluence of light and surface temperature is but little felt. No
sharp line of separation between these several classes is permissible,
however, since the habits normally belonging to the members of
one class are occasionally assumed by members of the other classes
as well, as must necessarily follow from the different conditions
governing their distribution.

DISTRIBUTION OF SHORE FISHES. 293

Shore Fishes.—The fishes of the first category number upwards
of three thousand five hundred species. Their range in the north
extends to, or beyond, the cighty-third parallel of latitude, but in
the Southern Hemisphere no species have been found to pass be-
yond the sixtieth parallel, although, doubtless, they exist along
some of the more southerly shore-lines. The Arctic fauna, or the
fauna occurring north of the sixtieth parallel of latitude, is, as far
as we are warranted in believing, a strictly homogeneous one, iden-
tical types largely characterising both the Old and the New World
divisions. The more extensively represented families are, among
the spiny-rayed fishes, the bull-heads (Cottida—Cottus, Icelus, Tri-
glops), the Agonide, lump-suckers (Discoboli), and blennies (Blen-
niidze—Anarrichas, wolf-fish) ; and among the anacanths the cod-
fishes, with the cod (Gadus), hake (Merlucius), and ling (Molva).
Among the physostomous fishes, or those in which the air-bladder
is provided with a pneumatic duct, the herring (Clupea) is repre-
sented by a limited number of species. The cartilaginous fishes
are very scarce; indeed, thus far only one species, the Greenland
shark (Lemargus), is known to penetrate north of the Arctic cir-
cle. The chimera, spiny dog-fish (Acanthias), and ray, are met
with along the southern borders of this tract.

The Antarctic shore fauna is in many respects closely related to
the Arctic, although nearly one-third of the generic types are
peculiar. As in the north, the cartilaginous fishes are scarce,
being represented by a single species of shark (Acanthias), and one
or more species of ray (Raja, Psammobatis). The Scorpznide and
Agonide among bony-fishes have each one genus, Sebastes and
Agonus respectively, which is held in common with the Arctic
fauna. The lophobranchs have in addition to the northern pipe-
fish (Syngnathus) the remarkable Protocampus, represented by a
single species of the Falkland Islands (P. hymenolomus). A most
interesting fact connected with the Antarctic fauna is the recur-
rence of types belonging to the far north, which are wanting in
the intermediate region. This we see in the single species of
spiny dog-fish (Acanthias vulgaris), which is a member of the
Arctic and north temperate faunas, but is absent from the equa-
torial region. The hakes comprise two species, one of which is
restricted to the northern waters and the other to the southern;
and a similar separation is found among the species of the Arctic

294 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

and Antarctic genus Lycodes. The gadoids are in both regions
accompanied by the parasitic hag (Myxine).

The shore fishes of the north temperate sea are largely identi-
cal in their general types in both the Atlantic and Pacific basins,
as well as on opposite sides of these basins. Thus, of the fishes
frequenting the British seas we find, among other genera, the fol-
lowing types also represented on the east coast of America : the
bass (Labrax), sea-perch (Serranus), porgy (Pagrus), bull-head (Cot-
tus), angler (Lophius), wolf-fish (Anarrichas), Zoarces, cod (Gadus),
hake (Merlucius), ling (Molva), and rockling (Motella); and among
physostomes the smelt (Osmerus), herring (Clupea), and conger.
The surmullets (Mullus), gurnards (Trigla), John Dorys (Zeus), and
some of the breams are wanting, or are but rarely met with.* The
cartilaginous fishes show as common to the East and West Atlantic
the ‘‘hounds” (Mustelus), rays, sting-rays (Trygon), and the elec-
tric rays (Torpedo) ; the true dog-fishes (Scyllium) appear to be
wanting on the East American coast, and Chimera has thus far
been found only in deep water.

Most of the genera of British fishes also frequent the Mediter-
ranean Sea, whose fauna effects a passage to the fauna of the
equatorial zone. The number of peculiar genera is very limited.
Among the newly appearing forms are the beryces (Beryx), star-
gazers (Uranoscopus), umbrines (Umbrina), barracudas (Sphyrena),
horse-mackerels (Caranx), and sea-horses (Hippocampus), members
of the (more southerly) American fauna as well (elements borrowed
from the fauna of the West Indies). The flat fishes—turbots,
plaices, flounders, soles (Rhombus, Pleuronectes, Solea, &c.)—ex-
hibit an increased development, while the gadoids rapidly diminish
in numbers. A most remarkable correspondence exists between
the Mediterranean fishes and those of the Japanese province—i. e.,
the coast of Asia between the thirtieth and thirty-seventh parallels
of latitude ; indeed, viewed from a generic standpoint, this corre-
spondence may be almost said to amount to identity. More than
one-half of all the generic types represented are fishes of the south
of Europe, and in many cases even the species are identical with

* The occurrence of Trigla cuculus on the American coast is considered
very doubtful by Jordan and Gilbert; on the other hand, Mullus barbatus,
supposed to be absent, has during late years been reported from Pensacola,
Florida, and Wood’s Holl, Massachusetts. (Smith’s ‘‘ Mise. Coll.,’’ 1883.)

DISTRIBUTION OF SHORE FISHES. 295

European forms.’ Several of the berycoid gezera inhabit the Japa-
nese and Mediterranean waters exclusively, while others, as the
red mullets, John Dorys, and trumpet-fishes (Centriscus), occurring
in these two districts and elsewhere, are wanting on both the East
and West American coasts.* How the transference of the Mediter-
ranean fauna to the East Asiatic coast, or the converse, was effected,
whether by means of a comparatively recent open water-way be-
tween the two regions, as has been supposed by some, our present
knowledge does not permit us to say.

The shore fishes of the south temperate zone, which extends
northward from the Antarctic faunal belt to about the thirtieth
parallel of south latitude, are most intimately related to those of
the north temperate, although very distinct from the forms which
occupy the intermediate or equatorial zone. Nor is this corre-
spondence restricted to generic types alone, since we find a consid-
erable number of northern species which, skipping the intermediate
tract, reappear here without having undergone even varietal modi-
fication. Such are the chimera (Chimera monstrosa), two species

of dog-fish (Acanthias vulgaris and A. Blainvillii), the monk-fish
(Rhina squatina), John Dory (Zeus faber), angler (Lophius piscato-
rius), bellows-fish (Centriscus scolopax), anchovy (Engraulis en-
crasicholus), sprat (Clupea sprattus), and conger (Conger vulgaris).
Among the marked differences separating the two regions may be
mentioned the substitution of the cottoids by the Notothenizw (fam-
ily Trachinidez) and the Discoboli by the Gobiesocide.t

Of the four south temperate provinces, that of the Cape of
Good Hope, the South Australian (with New Zealand), the Chilian,
and the Patagonian, the Australian is by far the richest, numbering
in its fauna not less than one hundred and twenty genera and two
hundred species. Two-thirds of all the genera occurring on the
coasts of Southeastern Australia and Tasmania are also represented
in the shore fauna of New Zealand, which comprises some one
hundred species. The New Zealand genera not represented in the
Australian coast are about twenty-six in number, with about an
equal number of species. The most marked difference between
the two nearly contiguous faunas is the absence of gadoids in the
Australian element, while the group is represented by not less than

* Centriscus scolopax is said to be accidental on the American coast,
+ The Gobiesocide have also northern representatives.

296 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

six genera (Gadus, Merlucius, Lotella, Motella, &c.) in the fauna of
New Zealand.—The Chilian fauna is generically closely related to
the South Australian, and contains but few types that are strictly
peculiar to it. One of its more remarkable features is the posses-
sion of a species of Polyprion (P. Kneri, from Juan Fernandez),
one of the Percidx, the only other known species of the genus (P.
cernium) being a member of the European fauna.* The number of
fishes thus far obtained from the Patagonian province is very
limited, and scarcely permits us to formulate any definite opinion
as to the characters of the entire fauna.

The equatorial shore fishes far exceed those of the temperate
zones both in number and diversity of form, agreeing in this re-
spect with the condition presented by equatorial land and fluviatile
faunas generally. It is here, too, that we find grotesqueness of
outline combined with a most varied and beautiful colouring, an
almost infinite arrangement of lively tints, scarlet, yellow, blue,
black, &c., imparting to the fishes of this tract an indescribable
brilliancy. Throughout the greater part of the equatorial or tropi-
cal belt there is manifest a strong faunal identity, rendering the
institution of ichthyic provinces practically impossible. Thus, the
greater number of the dominant types of the Atlantic Ocean are
also represented in the Pacific, and vice versa, and in many instances
even the species representing these types are identical. The fishes
of the tropical waters of the Indian and Pacific oceans are very
intimately related, the number of identical species ranging from
the Red Sea far into the Polynesian Archipelago being very great.
A limit to the eastward extension of the Indo-Pacific fauna appears
to have been set, however, by the cold current sweeping northward
along the western coast of South America, and as a consequence we
find a more or less distinct, or individualised, fauna along the east-
ern border of the great ocean. Among the more largely represented
generic or family groups of the equatorial zone are the sea-perches
(Serranus), snappers (Mesoprion), mullet-kings (Apogon), blow-
fishes (Chetodon, &c.), Scorpzenide, horse-mackerels (Caranx),
coral-fishes (Pomacentridex), Juliding, flat-fishes (Pleuronectide), —
herrings, and Murznide, several of which are more or less distine-
tive of the zone. In all of these groups the number of species in

* Obtained also in deep water by the United States Fish Commission.
(Jordan and Gilbert, ‘‘ Synopsis Fishes of North America,” 1852.)

PELAGIC FISHES. 297

the Indo-Pacific basin is very much greater than in the Atlantic.
The extensive development of reef-structures through the former
area, presenting unusually favourable conditions for existence, has,
doubtless, much to do with this comparative superabundance.

Pelagic Fishes.—Our knowledge respecting the fishes which
spend a considerable, or the greater, part of their existence on the
free surface of the oceans, borne resistlessly in the course of the
oceanic current, or inhabiting masses of floating sea-weed, although
still very meagre, is sufficient to indicate that the number of such
types is very limited. As with the other groups of fishes, they are
most numerous in the regions of high temperature, diminishing
rapidly as we proceed either north or south from the Equator.
Most of the tropical genera are also met with in the temperate
zones, and probably the converse is also true, although a number
oi exceptions have been indicated. The warm-water fishes become
rare beyond the fortieth parallel, and decline very rapidly with the
decline of the temperate fauna itself. Almost the only pelagic fish
of the Arctic Ocean is the Greenland shark (Lemargus borealis).

Among the better known bony-fishes that enter into the com-
position of the pelagic fauna are the flying-gurnards (Dactylopterus),
mackerels, tunny, bonitos, dolphins (Coryphena), skip-jacks, pilot-
fishes, sword-fishes, frog-fishes, scopelids, skippers, flying-herrings
(Exoceetus), sea-horses, porcupine-fishes, and sun-fishes (Orthago-
riscus). The cartilaginous fishes are preeminently pelagic in their
habits, and contribute largely to this fauna. The sharks are repre-
sented by a number of genera (Carcharias, Galeocerdo, Zygena,
Lamna, Notidanus, &¢c.), and by forms which are not only the
largest of their tribe, but approximately the largest of known fishes.
The basking-shark (Selache), the largest shark of the North At-
lantic, attains a length of more than thirty feet ; Carcharodon
Rondeletii, a tropical or sub-tropical species, the most formidable
of all sharks, has been known to measure forty feet, and Rhinodon
typicus, a species of the Indian Ocean, fifty to sixty feet. Rivals
to these monsters of the deep are the sea-devils or eagle-rays (My-
liobatide), many of whose forms (Dicerobatis, Ceratoptera) appear
to attain a length of twenty feet or more.

The similarity existing between the pelagic faunas of the At-
lantic and Indo-Pacific basins is very great, extending not only to

genera, but to species. A number of the forms are nocturnal in
14

298 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION,

their habits, living in a deeper zone during the day, and appearing
at the surface only at night. The majority of these are provided
with phosphorescent organs, a structure largely prevalent among
deep-sea fishes, to which these fishes effect a passage.

Deep-Sea Fishes——Much uncertainty still remains as to the
character of the abyssal ichthyic fauna, owing to the difficulty of
determining in many or most cases the depths whence specimens
caught in the net were obtained. But there can be no doubt that
many forms inhabit very nearly the greatest depths that have been
reached by the dredge. Ginther, in his ‘Introduction to the
Study of Fishes,” enumerates upwards of fifty forms which are
supposed to have been obtained from depths exceeding 1,000
fathoms; twenty-six from depths exceeding 2,000 fathoms; and
nine from depths of 2,500 fathoms or over. Additional forms have
since been obtained in the dredgings of the ‘‘ Talisman” and ‘‘ Al-
batross.” Bathyophis ferox and Halosaurus rostratus are reported
to have been dredged by the ‘‘Challenger” in water of 2,750
fathoms (5,019 metres), and Gonostoma microdon at an extreme
limit of 2,900 fathoms. Considerable doubt, however, attaches to
the last, since the fish is abundant in water of only moderate depth,
and may have been taken down in the descent of the dredge, or
captured only in its ascent. A similar doubt attaches to many of
the other forms with a reputed very broad bathymetrical range, as
it is hardly to be supposed that animals, organised specially to meet
the conditions (pressure, &c.) of life in the oceanic abyss, should
at the same time be so constituted as to endure with impunity the
very different conditions governing life near the surface. The
‘‘Talisman” obtained Alepocephalus rostratus at depths stated to
range between 868 and 3,650 metres, Scopelus Maderensis between
1,090 and 3,655 metres, and Macrurus affinis between 590 and 2,220
metres ; similarly, it is claimed that the ‘‘ Albatross” obtained
Cyclothone (Gonostoma) lusca and Scopelus Milleri in depths vary-
ing from 560 to 5,394 metres (2,949 fathoms—latitude 37° 12’
north; longitude 69° 39’ west), or over a vertical extent of 16,000
feet. Mr. Tarlton H. Bean justly considers the deep catch as doubt-
ful. Less doubt attaches to the position of Aleposomus (?) Copei
and Mancalias uranoscopus, both of which were obtained in the
5,394 metre haul." The deepest recorded find of the ‘‘Talis-
man” was in 4,255 metres (Bythites crassus)."?

DEEP-SEA FISHES. 299

The Gadidx, Ophidiidw, Macruride, and Scopelida make up a
very large proportion of the deep-sea fauna, which has thus far
yielded some ninety to one hundred or more genera. The eels
(Mureenide) are largely represented, and have been dredged from
depths extending to 2,500 fathoms. Very few cartilaginous fishes
were obtained by the ‘‘Challenger,” and these (Scyllium, Centro-
phorus, Raja) were restricted to water not much exceeding six hun-
dred fathoms, although the same group of fishes yielded specimens
to the ‘‘ Talisman” at nearly twice this depth (coast of Portugal).

Whether or not different zones of ichthyic life can be recognised
in the oceanic abyss may perhaps still be considered an open ques-
tion. Dr. Ginther maintains, as the result of his studies, that ‘‘as
far as the observations go at present, no distinct bathymetrical
regions which would be characterised by peculiar forms can be
defined,” and that, ‘‘if the vertical range of deep-sea fishes is
actually as it appears from the ‘Challenger’ lists, then there is no
more distinct vertical than horizontal distribution of deep-sea
fishes.” Asa result of the explorations of the ‘‘ Talisman,” Filhol
arrives at the opposite conclusion, and believes that a series of
more or less distinct zones can be indicated. Although in its gen-
eral features the abyssal fauna (‘‘ Bassalian” of Gill) is closely
related to that of the superficial tracts, yet a number of distinctive
elements, arising in part from certain remarkable abnormalities of
structure, or from the presence of types not elsewhere represented,
serve in a measure to define it. Professor Gill indicates twenty-
eight families of deep-loving fishes.™°

Of the two lowest orders of fishes, the Pharyngobranchii, as rep-
resented by the Amphioxus or lancelet, and the Marsipobranchii,
lampreys and hags, no unequivocal fossil remains have as yet been
discovered. Possibly, however, some of the singular tooth-like
bodies described as conodonts from the Cambrian and Silurian de-
posits, which by many authors are referred to the dental armature
of annelids, may belong to fishes more or less nearly related to the
modern hag.

The Elasmobranchii (sharks, rays) have their oldest representa-
tives in the Upper Ludlow horizon of the Upper Silurian formation,
being preceded in time by a bucklered ganoid, Pteraspis (Scaphas-
pis) Ludensis, from the Lower Ludlow. These earliest remains,
belonging to the family of the true sharks (Squalidz), are in the

300 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

form of teeth (Thelodus) and fin-spines or ichthyodorulites (On-
chus, Ctenacanthus). The order is but very scantily represented in
the Devonian deposits, but in those of the succeeding Carboniferous
age (sub Carboniferous limestone) it acquires a profuse develop-
ment, the pavement-teeth of forms generally considered to be allied
to the modern ‘‘ Port-Jackson” shark (Cestracion) being particu-
larly abundant—Helodus, Orodus, Chomatodus, Petalodus, Cochlio-
dus, Psammodus. The relationships of these genera are, however,
still very obscure, and not impossibly they constitute a group apart
by themselves — Psammodortes. Less doubtful representatives
(Strophodus, Acrodus, Hybodus) of the type of cestraciont fishes
appear in the early and middle Mesozoic periods, Triassic and
Jurassic, and in the chalk the teeth of Ptychodus are still very
abundant. But in the latter period the more modern type of
sabre-toothed sharks and dog-fishes, largely represented by existing
genera, Notidanus, Scyllium, Lamna, Carcharias, Hemipristis, Gale-
ocerdo (Corax, Otodus—extinct), appear to have gained the ascend-
ency, which they retained throughout the subsequent Tertiary pe-
riods. The most important of the later genera, and especially
distinctive of the Miocene deposits, is Carcharodon. The earliest
unequivocal traces of rays occur in the deposits of Jurassic age,
although not impossibly some of the hypothetically placed forms
of the later Paleozoic periods may belong to this group, or, at any
rate, effect a union between it and the sharks. Of this nature
appear to be the Jurassic Thaumas and Squaloraja, both of them
nearly allied to the modern (and Cretaceous) Squatina. The true-
and sting-rays are abundantly represented, particularly by frag-
ments of their dental armatures, throughout the Tertiary deposits,
the modern genera (Trygon, Myliobatis, tobatis, Zygobatis, Raja)
predominating. The saw-fish (Pristis) and torpedo-ray date from
the Eocene, and not impossibly from the Cretaceous period.
Appearing almost simultaneously with the selachians, but at-
taining a much earlier considerable development, are the ganoids,
a class of fishes which in the earlier geological periods exhibit a
remarkable diversity of structure, but at the present day are com-
prised within a very limited number of genera, whose members,
with the exception of the partially marine sturgeon (Accipenser),
are all inhabitants of fresh water. Three or more distinct types,
based upon characters drawn from the structure of the dermal

PALEOZOIC FISHES. 301

armor, may be conveniently recognised: the osseous plated ganoids,
as represented by the sturgeon ; the enamel rhomb-plated ganoids,
typified in the American alligator-gars (Lepidosteus) end the Afri-
can Polypterus ; and the cycloid scaled gancids, exemplified in
the American Amia, which may in a measure be said to connect
these fishes with the herring among the teleosts. None of these
types appear to be represented in the Silurian pericd, unless, in-
deed, the group of the bucklered ganoids, to which the ancient
Scaphaspis Ludensis, and the greater number of the Devonian
forms (Cephalaspis, Pteraspis, Pterichthys, Coccosteus) belong, be
considered to be nearly related to the sturgeons. This relation-
ship, however, requires further demonstration before it can be
accepted as a fact; indeed, it has recently been attempted to show
that some of these most ancient ichthyoid forms—e. g., Pterichthys
—are not fishes at all, but members of what may, perhaps, be con-
sidered to be a degenerated group of the lower Vertebrata, the
tunicates.. The almost total obliteration of the bucklered type of
ganoid with the close of the Devonian period is very remarkable,
and has not yet received a satisfactory explanation. It has been
conjectured by some that these fishes early withdrew to fresh water,
and that, in the absence of fresh-water deposits of any magnitude
in the period succeeding, they have necessarily left behind but
scanty traces of their existence. It must be confessed, however,
that this explanation is more in the nature of an assumption than
anything else, and has but little positive to bear it out. In how
far the Devonian fishes were of a fresh-water habit still remains to
be determined, but it seems more than probable that they were
largely of this, or at least of a brackish-water, character. The re-
mains of the sturgeon are not known prior to the Eocene period,
although a direct forerunner (Chondrosteus), uniting this family
with the Spatularide, occurs as low down as the Lias.

The non-bucklered ganoids of the Devonian period (Holop-
tychius, Glyptolepis, Dipterus, Osteolepis, Diplopterus) belong
principally to the type of the fringe-finned or crossopterygian
Polypteri, which effect a passage to the lung-fishes (Dipnoi). This
series, which is represented by both scaled and plated forms, is
continued into the Carboniferous period (Rhizodus, Dendrodus,
Megalichthys, Ceelacanthus) ; but here, as in the succeeding Permian
period, they are already largely replaced by the lepidosteoid type

302 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

(Palzoniscus, Amblypterus), which has its forerunner in the Devo-
nian Chirolepis. The primitive heterocereal tail which characterises
the ganoid fishes of the Paleozoic era, and which is still borne by
many of the rhomb-plated fishes of the early Mesozoic period—
Paleoniscus, Ischypterus, Catopterus—is converted by gradual
modification into the higher homocereal type, which distinguishes
the more important genera of Jurassic fishes (Tetragonolepis, Dape-
dius, Lepidotus, and the teleostoid Leptolepis). In Semionotus,
which ranges from the Trias into the Lias, the tail is of a well-
marked transitional character. Very few of the Jurassic Ganoidei
survive into the Cretaceous period, which practically marks the
final collapse of this important order of animals, henceforward suc-
ceeded by the more highly constituted bony-fishes. The most im-
portant remaining group is that of the pyenodonts, or bean-toothed
ganoids, whose numerous closely related forms have been referred
to several distinct genera, which range collectively from the Car-
boniferous period (Platysomus) to the Eocene. Among the Juressic
genera are Microdon, Mesodon, Gyrodus, and Pyenodus, the last, a
remarkable example of a persistent type, surviving the close of the
Cretaceous period into the Tertiary. Of the group of the cycloid
scaled ganoids (Ganoidei cycliferi), represented at the present day
by Amia, probably the earliest unequivocal remains are those of the
genus Amia itself, which appear in the Cretaceous deposits ; by
many naturalists, however, several Paleozoic forms, as Holopty-
chius, Asterolepis, Bothriolepis, and Ccelacanthus, are referred to
this group, and with them also the celacanthine Cretaceous genus
Macropoma.

The lung-fishes (Dipnoi), which at the present day are repre-
sented by the three very isolated genera Lepidosiren (Brazil),
Protopterus (Africa), and Ceratodus (Australia), have left un-
doubted traces of their existence as far back as the Permian
period, when the genus Ceratodus itself appears (Bohemia, Texas),
presenting us with the most remarkable instance of persistence in
the whole range of vertebrate animals. Not unlikely the genus
may be found to be of still older date, and to have been nearly
contemporaneous with its formidable predecessor, the Dinichthys.
Remains of Ceratodus have been found throughout the entire series
of Mesozoic deposits, from the Trias to the Cretaceous inclusive.
Lepidosiren and Protopterus are not known in a fossil condition.

FOSSIL FISHES. 303

The osseous fishes proper appear for the first time in Cretaceous
strata, being immediately preceded by the teleostoid group of ga-
noid fishes of the family Leptolepidx, which effects a passage to
them. Indeed, by many authors the genus Leptolepis and its
Jurassic allies (Caturus, Thrissops, &c.) are classed with the for-
mer, and placed near the herring, with which they appear to have
been most nearly related. Although both the physoclist and phy-
sostome types, or those in which the swimming-bladder is closed
off from, or remains connected with, the gullet, appear very nearly
simultaneously in the same deposits, and consequently by their
occurrence give no evidence as to their respective antiquity, there
can be no question that the physostome is the more ancient type,
the severance of the bladder in the physoclists being the result of
the disuse of parts. This is further proved by the existence of a
connecting air-bladder among the recent (and, doubtless, also among
the ancient) ganoids. The Cretaceous teleosts belong largely to
existing types—Clupea (herring), Osmerus (smelt), Esox (pike),
Beryx; but it is not until the Eocene period that we find a repre-
sentative modern ichthyic fauna. To this, and the succeeding
Tertiary period, most of the more prominent existing types date
their first appearance. In addition to a very large representation
of both the arthropterous and anarthropterous forms, the Eocene
deposits contain remains of the Lophobdranchii (Syngnathus, pipe-
fish), Plectognathi (Diodon, porcupine-fish; Ostracion, trunk-tish),
and Apodes (Anguilla, eel).

The study of the distribution of fossil fishes renders evident
two important facts: First, that there has been a progressive modi-
fication and evolution from less to more highly organised types;
and, secondly, that among the almost innumerable forms of com-
paratively recent origin, our existing ichthyic fauna still holds the
wreck of a past fauna, whose period of decline belongs already to
the earlier part of the earth’s history. It, moreover, reveals an
extraordinary persistence on the part of some of the individual
types. The occurrence of the recent genus Ceratodus in deposits as
ancient as the Permian is certainly very remarkable, but it does
not argue, as some would lead us to believe, that this particular
fish has undergone no modification since the period of its first
introduction. The fact that its remains have been found fossil in
the deposits of Europe and America, whereas at the present time it

304 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

is found exclusively in Australia, would seem to imply a different
distribution of land and water masses than now exists. But there
appears to be no doubt, from their association with a marine fauna,
that the early members of the genus were of an oceanic character,
and that the fresh-water habit was obtained as the result of later
modifications. The peculiar distribution would then be readily
accounted for. It appears more than probable that from the order
of fishes represented by this genus have been descended at least
some of the earlier amphibians; if this be true, it would seem that
the lungs of the dipnoans had been developed when the animals
were still more or less strictly marine. The genetic relationship of
the two remaining genera, the South American Lepidosiren and
the African Protopterus, to Ceratodus still remains to be deter-
mined; but the development of an additional lung in these forms,
coupled with the circumstance of their broad geographical isola-
tion, would indicate an ancient differentiation of the two groups of
the Dipneumones and Monopneumones.

In tracing the phylogeny of the class of fishes as a whole we
are presented with certain difficulties which in the present state of
our knowledge prove an insuperable obstacle to the solution of the
problem. Paleontology thus far offers no positive clue as to what
might have been the direct ancestors of the animals in question,
and until it does so inferences drawn from purely zoological char-
acters will be largely in the nature of pure hypotheses. The earli-
est fishes that appear, although obviously of a much less perfect
structural type, exhibit very nearly the amount of specialisation
seen in the modern forms, and are evidently far removed from the
period of their first origination. Whether, therefore, the tunicates,
which unquestionably possess many points of structural relation-
ship with the fishes, are their true ancestors or not, or whether,
instead of representing primitive vertebrate types, they are merely
the degenerated remains of a more highly constituted ichthyic
stock, must still be considered an open question. Nor would it be
safe to affirm that the most ancient representative of the class was
a form either closely or remotely allied to amphioxus, the lancelet,
or that the latter is an ancient type at all. If the views recently set
forth by Professor Cope ™ as to the tunicate affinities of Pterichthys
and its allies be proved to be correct, then, indeed, the presumptive
evidence would be very great for concluding that what have hither-

AMPHIBIA. 305

to been generally considered to constitute an abnormal type of the
Mollusca are in reality the true progenitors of the fishes. The facts
in the case, however, require further substantiation.

The phylogenetic relationship existing between the selachians
and ganoids is equally obscure as that which exists between fishes
generally and the other classes of animals. Both types are known
to us in their oldest forms from very nearly the same horizon, and
consequently give no indication as to priority of birth. Much
more positive indication in this direction is afforded with respect
to the lung-fishes and teleosts, the former of which appear to be
clearly related to, and to have been derived from, the dipteroid
ganoids (of the type of Dipterus), and the latter to have held a
similar relationship to the rhomb-scaled ganoids, possibly of the
type of Leptolepis. From the former, apparently, have descended
the amphibians, while the latter have continued to develop as the
dominant fish-fauna of existing waters. That the fresh-water forms
are modified descendants of types originally inhabiting the seas
there can be no reasonable doubt. It is impossible to state when
the earliest differentiation of marine and fresh-water forms was
effected, but there is every reason for supposing that it dates back
far into the Paleozoic era, and that some, if not many, of the
Devonian fishes were of a strictly fresh-water habit.

AMPHIBIA,

The most salient facts that present themselves in connection
with the geographical distribution of the Amphibia are, first, their
almost complete absence from oceanic islands—the Seychelles, New |
Caledonia, and the Feejee and Solomon Islands forming island
groups exceptional to a general rule—and, secondly, the very nearly
universal limitation of the tailed forms, sirens, newts, salamanders,
&c., to the Northern Hemisphere. The nature of the first condition
has already been discussed in treating of the dispersal of animals
generally. The total number of known forms are comprised, ac-
cording to the latest researches of Boulenger, in somewhat more
than one hundred and forty genera and nine hundred species, of
which only twenty-seven genera and seventy species belong to the
urodelous or tailed division, eleven genera and thirty-one species
are ceecilians (Apoda), and the remainder, one hundred and five
genera and eight hundred species, frogs and toads (Anura).

306 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

The ceecilians are tropical forms belonging to the East Indies,
Africa (with the Seychelles—Hypogeophis rostratus), and America.
The American species, including all of the genus Ceecilia itself, are
about twenty in number, and range from Mexico to Peru and
Brazil.* Remarkable instances of divided genera are presented by
Dermophis, which possesses five American species and one from
West Africa (D. Thomensis), and Ureotyphlus, represented by two
species in Malabar and likewise one in West Africa.

The urodele amphibians are comprised in four families : The
Sirenidzx or sirens, with two or three species, inhabiting the South-
eastern United States; the Proteidz, with two genera, Proteus and
Menobranchus (or Necturus), the former confined to the subter-_
ranean waters of Carinthia, Carniola, and Dalmatia, and the latter
to the streams of Eastern and Central United States and Canada;
the Amphiumide, with three genera, two of which, Amphiuma and
Menopoma, represent North American forms, while the third, Sie-
boldia (Cryptobranchus or Megalobatrachus), which is closely re-
lated to the menopomas, is confined to Japan and China; and the
Salamandride (newts, salamanders, &c.), comprising upwards of
ninety species, very extensively distributed throughout temperate
Eurasia and North America, with some fifteen or more species in
tropical America (from Mexico southward—Amblystoma, Spelerpes),
a limited number in North Africa, and two (Tylotriton) in the
Himalayas. The North American forms belong principally to the
genera Plethodon, Desmognathus, Diemyctylus, Amblystoma (with
Axolotl), and Spelerpes, the first two of which appear to be restricted
to the Western Hemisphere.t Spelerpes has one species (S. fuscus)
in the south of Europe, and Amblystoma one (A. persimile) in
Siam, remarkable instances of separation in genera. The urodele
Amphibia of North America, north of the Mexican boundary, num-
ber about fifty species. The permanent larval forms of one or more
species of Amblystoma (A. tigrinum, A. mavortium), known as

* Boulenger gives the range of Chthonerpeton indistinctum as extending
to Buenos Ayres; but this is considered doubtful by Peters (‘t Monatsb. Berl.
Akad.,’’ 1879, p. $40).

+ American zoologists recogrise the Plethodontide (with Spelerpes), Des-
mognathide, and Amblystomide as distinct families; Diemyctylus, repre-
senting the Pleurodclide, is by Boulenzer considered to be synonymous with
the Eurasiatic Molge (Triton of Laurenti).

AMPHIBIA. 307

axolotls, occur in various parts of Mexico and the Western United
States (California, Wyoming).

The greater number of the Old World salamandroids belong to
the genus Molge (or Triton), whose range extends from Great
Britain (M. cristata; M. palmata) to China and Japan (M. pyr-
rhogastra; M. Sinensis), and south to Syria and the Mediterranean
coast of Africa. The species having the most extended range ap-
pear to be M. cristata and M. vulgaris, both of which are distrib-
uted throughout the greater part of Europe, and largely also over
temperate Asia. The most northerly point reached by any species
seems to be about 63° 30’ (M. vulgaris or aquatica, in Norway).
The Alpine triton (M. alpestris) ascends the Alps, according to
Fatio, to an elevation of about 8,000 feet (2,500 metres), while a
Mediterranean species (M. montana) inhabits the Lago d’Argento,
on Monte Cinto, in Corsica, at an altitude of 6,000 feet. The
genus Salamandra has three species, which collectively inhabit the
greater part of Central and Southern Europe, the Caucasus, Asia
Minor, and Algeria. Salamandra atra, the black or rain salaman-
der, inhabits the mountain-regions of Savoy, Switzerland, and
Austria between altitudes of 2,500 and 10,000 feet.

The anurous, or tailless, amphibians (frogs and toads), which,
as has already been seen, comprise not less than eight hundred
species, enjoy a much broader distribution than the tailed forms,
being absent only from the regions of high northern and south-
ern latitudes, and the remote oceanic islands. The genera Rana
and Hyla are each represented by a single species in the Solo-
mon Islands, and Cornufer (Ranidee) by three species (C. dor-
salis, C. Vitianus, C. unilineatus) in the Feejee Islands. The only
family that is entitled to be considered in any way cosmopolitan is
that of the toads (Bufonide), which are only absent, apart from
local areas and the strictly oceanic islands, from Madagascar, New
Guinea, and New Zealand. The genus Bufo, which in itself com-
prises nearly eighty out of a total of some ninety species belonging
to the family, covers the entire range, with the exception of Aus-
tralia, where it is replaced by the genera Pseudophryne, Notaden,
and Myiobatrachus. The most broadly distributed species of the
genus is the common European toad or paddock (B. vulgaris),
whose range comprises practically the whole of Europe, Asia as
far east as Japan, and Northern Africa; in Switzerland it ascends

308 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

the Alps to a height of nearly 7,000 feet. Bufo calamita and B,
viridis are likewise distributed throughout the greater part of
Europe, the latter extending its range eastward to Turkestan.— The
greater number of the American species occurring north of the
Mexican boundary belong to the Sonoran transition-tract, where
some six or seven species are met with. The common form of the
Eastern and Southern United States is the Carolina toad (Bufo
lentiginosus), of which several distinct varieties are recognised. A
number of bufonine species are found in the West Indies, and Bufo
(Chilophryne) dialophus is said to inhabit the Sandwich Islands.

Next to the toads the most broadly distributed family is that
of the true frogs (Ranidz), which are most abundantly developed
in the Oriental and Ethiopian tracts, but are almost entirely absent
from Australia. Of some two hundred species (representing eighteen
genera), recognised as belonging to this group, somewhat more than
half belong to the genus Rana itself, whose distribution is practi-
cally that of the family. The genus is absent from the southern
parts of South America—in the whole of which continent there
have been determined thus far only three or four species—and from
New Zealand, but is represented by a single species (Rana Papva)
in North Australia. <A solitary species (Rana Krefftii) is also found
in the Solomon Islands. The most broadly diffused Old World
form is the green or edible frog (Rana esculenta), whose habitat
extends from England and Scandinavia to North Africa, and east-
ward through Central Asia to China an@ Japan; the species is
wanting in the island of Sardinia.* Somewhat less broadly dis-
tributed through Eurasia is the common freg (R. temporaria), which
is the most northerly of known species, ranging in Norway (var.
platyrhina) to beyond the seventieth parallel of latitude. In the
Alps it still frequents the waters at an elevation of 8,000 feet.

The two commonest species of Eurasian frog have their American
representatives in the shad- or leopard-frog (R. halecina) and wood-
frog (R. sylvatica)—the latter by some authors considered to be
identical with R. temporaria—both of which are widely distributed
in the United States. The largest American species of the genus,
which alone represents the family north of the Mexican frontier,

* Schreiber affirms that the species is also wanting in Great Britain; but

the British Muscum is in possession of a specimen from Cambridgeshire
(Boulenger, ‘‘ British Museum Catalogue,’’ 1882).

AMPHIBIA. 309

is the common bull-frog (R. Catesbiana). Among the more im-
portant remaining genera of Ranid are Rhacophorus (with Polype-
dates, according to Boulengerx), whose thirty or more species inhabit
Japan, the Philippines, Southeast Asia, India (with Ceylon), and
Madagascar; 'xalus, with about twenty-five species, restricted to
the East Indies; and Rappia, with a nearly equal number of species,
inhabiting tropical Africa.

The tree-frogs (Hylide), with upwards of one hundred and sixty
species, find their greatest development in the Neotropical region,
which contains somewhat more than one hundred species. The
genus Hyla itself is represented by nearly ninety species, or by
nearly three-fourths of all the known forms. The species of the
North American fauna are comprised in the genera Hyla, Acris,
and Chorophilus. Temperate Eurasia has but a solitary representa-
tive of the family, the common tree-frog (Hyla arborea), which, in
its several varietal forms, is distributed from Great Britain and the
Canary Islands to Japan. Hyla Chinensis and H. annectens, the
latter from North India, are the only other Asiatic species. The
genus Hyla is wanting in the Ethiopian realm, but is represented
by several species on the continent of Australia, whose amphibian
fauna is made up almost exclusively of the families Cystignathide
(about twenty species), Bufonidie (six species), and Hylide (eleven
species—Hyla and Hylella).

Scarcely inferior in point of specific development to the tree-
frogs are the Cystignathidz, whose one hundred and fifty or more
species are almost entirely restricted to Australia (with Tasmania)
and South America, a few species penetrating northward into Mexico
and the West Indies, and three or four into the Southern and Western
United States (Florida, Texas, California). The family may, there-
fore, be said to be distinctive of the Southern Hemisphere. The
most abundantly represented of its numerous genera is Hylodes
(forty-five species, tropical America), peeping-frogs, many of whose
species partake of the habit of the common tree-frogs. Collectively
the species are very broadly distributed, and penetrate far beyond the
region of elevated temperatures. Hylodes leptopus, about the most
southerly of all known species of frog, descends to the Strait of
Magellan, while H. Whymperi was obtained by Mr. Whymper on
the slopes of Chimborazo at an altitude of 18,200 feet. Paludicola
marmorata (Leiuperus viridis), a member of the same family, was

310 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

found by Tschudi in the Peruvian Andes at an elevation of nearly
16,000 feet. Among the more distinctive forms of Cystignathide
are the horned frogs (Ceratophrys), which inhabit tropical America
from Guiana to Uruguay.

A remarkable instance of a divided family among the Anura is
furnished by the Dendrobatide, which comprise two genera and
ten species, one genus, Mantella, being confined to Madagascar and
Nossi Bé, and the other, Dendrobates, to tropical South America.
The intermediate tracts are entirely devoid of representatives of the
family. The number of families restricted to a single zoogeographi-
cal region is five, of which four characterise the Neotropical realm
—Dendrophryniscidx, Amphignathodontide, Hemiphractide, and
Pipida—and one, the Dactylethride, the Ethiopian. The most
limited of all the families is the Pipide, which is restricted to a
single species, the Surinam toad (Pipa Americana), an inhabitant
of Guiana and Brazil.

Of the four primary groups to which the animals of this class
are referable, the Stegocephala (corresponding to the Labyrintho-
dontia of most authors), Gymnophiona (ceecilians), Urodela (sala-
manders, tritons), and Anura (frogs and toads), the first acquires
special geological importance from the fact that all, or very nearly
all, of the older forms are comprised within it. Remains of Urodela
are only doubtfully known from the Paleozoic deposits, while the
anurous type does not appear before the Tertiary epoch; no fossil
ceecilian has as yet been discovered.

The now wholly extinct order Stegocephala, which comprises
salamandroid and ophidian forms more or less covered with a pro-
tecting armour of bony (ganoid) plates, dates from the Carbon-
iferous period (Hylerpeton, Batrachiderpeton, Pelion, Dolichosoma,
Ophiderpeton), when, or at a still considerably earlier era, they
appear to have become differentiated from the type of lung-fishes
(Dipnoi) or of the dipteroid ganoids. A further development of
types, with a partial persistence of Carboniferous genera, is mani-
fest in the Permian deposits, where, as in the older strata, the
forms are principally referable to the division Ganocephala (Archee-
gosaurus, Dendrerpeton, Branchiosaurus, Protriton,* Hylonomus,

* Protriton Petrolei is by Dcichmiiller considered to be identical with
Branchiosaurus gracilis.

AMPHIBIA. oli

Limnerpeton, Melanerpeton), in which the peculiar labyrinthine in-
folding of the teeth, distinctive of the true labyrinthodonts, is
largely absent. The apodal and cecilian-like division Aistopoda
is represented among other forms by the Carboniferous genera
Dolichosoma and Ophiderpeton, and by Palzosiren and the Ameri-
can Molgophis. Contemporaneously with these types we have also
the true labyrinthodonts, whose earliest member appears to be
Baphetes, from the Carboniferous deposits of Pictou, Nova Scotia.
The full development of this group does not obtain, however, be-
fore the Triassic period, at the close of which the entire order of
animals seems to have become extinct in most regions.* Among
the more distinctive genera of this period are Labyrinthodon, Mas-
todonsaurus, Trematosaurus, and Metopias, to one or several of
which probably belong the foot-prints of the fanciful animal desig-
nated Cheirotherium.

Of the perennibranchiate division of the Urodela, in which ex-
ternal gills are retained throughout the entire existence of the
animal (Siren, Proteus), we have as yet no positive indications in
any of tne rock-formations. The Cryptobranchia, which retain a
gill-opening after the absorption of the gills—the American Am-
phiuma and Menopoma, and the giant salamander of Japan, Cryp-
tobranchus Japonicus—seem to have one or more fossil representa-
tives in the genus Andrias (Cryptobranchus of some authors), from
the Miocene deposits of Oeningen, Germany, to which are referred
the remains presumed by Scheuchzer to be those of earliest man
(Homo diluvii testis). It is certainly a very remarkable fact in dis-
tribution that the only link uniting the so widely separated, but
closely related, genera Menopoma and Cryptobranchus, should be
this extraordinary form from the middle Tertiary period. Its ex-
istence would seem to indicate a former much broader diffusion of
this particular group of animals, and a very different distribution
of land and water areas than now obtains.—The caducibranchiate
urodeles (salamanders, tritons), which in their transformation to lung-

* Brachyops, from the Damuda beds of India, and one or two other genera
of labyrinthodonts have been indicated as belonging to the Jurassic period,
but it may be questioned whether the age of the deposits in which these
remains occur has been as yet satisfactorily determined. Excepting these
somewhat doubtfully placed forms, no amphibians are known from Jurassic
strata.

$12 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

breathers pass one stage beyond the cryptobranchs in the oblitera-
tion of the gill-aperture, date from the Eocene period, when forms
more or less nearly allied to recent types appear. Both Triton and
Salamandra are represented. Remains of tailless amphibians (Anu-
ra), more or less nearly allied to modern forms, have been obtained
from the Tertiary lignitic and fresh-water strata (Oligocene, Mio-
cene) of Western and Central Europe. Paleobatrachus diluvianus,
one of the oldest known forms, is from the lignitic strata of Orsberg,
near Bonn, Germany. The lacustrine deposits of Oeningen have
yielded several extinct genera, among which are Latonia (related to
the Brazilian horned toad, Ceratophrys), Paleophrynus (a bufonine
type), and Pelophilus, the last not impossibly a true Bombinator.
Among recent genera, Rana, Bufo, and Pipa have also Tertiary
representatives.

The paucity of remains of existing types of amphibians, com-
bined with the circumstance of their very late appearance, renders
impracticable the determination of the phylogenetic relationships
which bind together the various groups. Equally uncertain are
the stages which mark the differentiation of the modern fauna
from that of the Paleozoic and the early Mesozoic periods, nor is
it likely that any progress towards the sclution of this problem
will be effected until the void which is caused by the almost total
absence of amphibian remains from the deposits of Jurassic and
Cretaceous age will have been in great part filled.

That the animals in question are derived either in whole or in
part from the cipnoan type of fishes there is very little doubt, but
the immediate connecting link or links between their ichthyic pro-
genitors, whatever these may have been, and the earliest stego-
cephalic forms are still wanting. The apparently sudden disap-
pearance with the Triassic period of the largely represented order
which contained all, or very nearly all, the earlier forms of amphib-
ians, without leaving in the modern fauna any positive indications
of its former existence, is not a little surprising, but it appears not
unlikely that the ceecilians, which in many points of structure
resemble the ophidian labyrinthodonts, represent at least a part of
this ancient stock. Again, by many geologists the crocodiles are
assumed to be the modified descendants of the true labyrintho-
donts.

TURTLES. 313

REPTILES.

Chelonia.—The total number of known species of chelonians is
estimated by Hoffmann (1880) to be somewhat more than two hun-
dred and fifty. Of these only five are marine forms, the rest being
inhabitants of the land and its fresh waters. The former, com-
prised in the genera Dermatochelys (or Sphargis), Chelone, and
Thalassochelys, are very broadly distributed throughout the tropi-
cal and sub-tropical or temperate waters of both the Old and the
New World, most of the species being cosmopolitan, or nearly so.
Dermatochelys coriacea, the leathery turtle, is found along the
American border from Brazil to South Carolina and Massachusetts,
exceptionally on the European coast, and in the Indian and Pacific
oceans, from Africa to Chili. The green turtle (Chelone viridis),
which is held in such high estimation as an article of food, has an
equally extended range, although it is but very rarely found on the
European coast (England to the Mediterranean). Of still rarer oc-
currence in the European seas is Chelone imbricata, the hawk’s
bill, which yields the tortoise-shell of commerce, and whose habitat
embraces nearly the whole circumference of the globe. The log-
gerhead (Thalassochelys corticata) is abundant on both sides of the
Atlantic, and in the Mediterranean, and is at rarer intervals also
met with in the Indo-Pacific basin.

The land and fresh-water chelonians have a very unequal dis-
tribution, being most abundant in the region of the tropics, and
rapidly diminishing as we pass either north or south into the tem-
perate zones, The greatest number of forms belong to tropical and
sub-tropical America, and the smallest number to Australia and
temperate Eurasia, each of which possesses some fifteen species.
The northern limit reached by these animals in the Western Hemi-
sphere is about the fiftieth parallel of north latitude (Chelydra
serpentina), and not improbably the same parallel marks the cor-
responding general limit in the Eastern Hemisphere, although in
Europe Cistudo lutaria or Europa, the most wide-spread spccies
of the continent, is found as far north as the fifty-fourth parallel
(Mecklenburg), and possibly still farther. The total number of
European species is five, most of which more properly belong to
the region about the Mediterranean. No species is known from
Great Britain, the Scandinavian Peninsula, Denmark, Holland, or

314 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Belgium. Cistudo lutaria and Testudo Greca, the latter intro-
duced, inhabit the waters of Southern France; the first of these
also inhabits Switzerland, but it is only doubtfully indigenous to
that country. The number of species occurring in North America
north of the Mexican boundary is about forty, nearly one-half
of which properly belong to the Southern United States. Among
the commoner or better known forms are the box-turtles (Cistudo,
Cinosternum), wood-turtles (Chelopus), painted-turtles (Chrysemys),
marsh-turtles (Malacoclemmys), terrapins (Pseudemys), musk-turtles
(Aromochelys), snappers (Chelydra), and soft-shells (Aspidonectes),
all of which are very broadly distributed, especially in the Eastern
and Southern United States. The species having the most ex-
tended range is the common snapper (Chelydra serpentina), which
is found from Canada to Ecuador. Two other species, the common
wood-turtle (Chelopus insculptus) and the painted-turtle (Chrysemys
picta), range as far north as Canada.

Most of the species of Chelonia are restricted to a single faunal
region, and where identical species are found in more than one
continent, the range of the species on the continent not properly its
home is, as a rule, very limited. Two species are known to be
common to Europe and (North) Africa—Testudo nemoralis and
Cistudo lutaria (C. Europza); one species, Pyxis arachnoides, is
common to the continent of Africa (with Madagascar, and some of
the neighbouring islands) and India; and likewise one, Manauria
fusca, common to the East Indies (Java, &c.) and Australia. Tur-
tles are wanting in the true oceanic islands, but they are sufficiently
abundant in many of the continental islands, even where these are
distant several hundred miles from the nearest mainland. Two of
the most ponderous representatives of the order belong to such isl-
and groups: the Galapagos turtle (Testudo nigra) and the elephant
turtle (T. elephantina), the latter, whose weight is known to reach
five hundred pounds, inhabiting the Seychelles and some of minor
island groups of the Mozambique Channel.

Of the four more generally recognised families of land and
fresh-water turtles, the Testudinide, Emyd, Chelyde, and Triony-
chide, only the first has representatives in all the major divisions
of the earth’s surface. Australia is lacking in both the Emydex and
Trionychid, the latter being also absent from South America,
while the three southern continents are almost the sole possessors

LIZARDS. 315

of the Chelydz. Remarkable instances of discontinuous genera
are seen in Hydromedusa, one species of which inhabits the Oriental
realm and the remainder the continent of South America, and in
Podocnemis, whose species are divided between South America
and Australia.

The earliest chelonian remains occur in deposits of Jurassic age
(Switzerland, Germany, France), in which a well-marked differentia-
tion of the modern families Emyde (as seen in the genera Thalas-
semys, Eurysternum, Tropidemys, Helemys, the last supposed to
have been closely related to the American snapper) ‘and Chelyds
(Plesiochelys, Idiochelys, Craspedochelys) already appears. The
number of forms is materially increased in the succeeding Creta-
ceous deposits, where, in addition to the representatives of the two
families already indicated (e. g., Platemys, Pleurosternum, Adocus,
Euclastes, Osteopygis), we have those of the Trionychide and
Cheloniidss (Trionyx, New Jersey; Chelone, Maestricht chalk, and
greensand of New Jersey). Protostega gigas, a marine turtle from
the deposits of this age of Kansas, attained a length of upwards of
twelve feet. Many of the recent genera, as Testudo, Chelydra,
Emys, Cistudo, &c., appear as fossils in the early or middle Tertiary
deposits. The most extraordinary of all extinct forms is the giant
land-tortoise of the Siwalik Hills of India, Colossochelys atlas,
which measured apparently not less than fifteen to twenty feet in
length. Of somewhat less than one-half these dimensions was the
Macrochelys mira, from the molasse of Southern Germany (Ober-
kirchberg, near Ulm), whose modern representative is the Missis-
sippi snapper (Macrochelys lacertina).

Lacertilia.—The number of known species of lizard is esti-
mated by Giinther to be about seventeen hundred, of which by far
the largest part is confined to the warmer regions of the earth’s
surface. But comparatively few forms are found to pass beyond
the fortieth parallel of latitude, and at about the sixtieth parallel
(north) the order practically disappears. The most northerly spe-
cies is Lacerta vivipara, whose range comprises nearly the whole of
Europe, and extends northward to the seventieth parallel (in Nor-
way); it is accompanied as far as Lapland by the no less broadly
distributed blind-worm (Anguis fragilis). In the Western Hemi-
sphere the northward extension of the order is much more limited
than in the Eastern, and it would appear that only one species, a

316 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Gerrhonotus, passes beyond the fiftieth parallel; in the Middle
United States the northern skink (Eumeces septentrionalis) pene-
trates into Minnesota, and along the Atlantic border Eumeces fas-
ciatus, a species, singularly enough, also found in Japan, forms
part of the Massachusetts fauna. The most southerly range of any
species is that of Liolemus Magellanicus, which reaches the Strait
of Magellan.

In the whole of Europe north of the forty-fifth parallel of lati-
tude, or what might be considered to be Central and Northern
Europe, theré are scarcely more than a dozen species of lizard, of
which nearly one-half belong to the genus Lacerta, or common
lizard. Scandinavia, Great Britain, and Denmark have each three
(and the same) species: Lacerta vivipara, L. agilis, and Anguis
fragilis. An additional species, the wall-lizard (L. muralis), be-
longs to Belgium and Holland, and a fifth one, the green lizard
(L. viridis), which has also found a congenial home on the island
of Guernsey, to Germany. All of these species form part of the
southern or Mediterranean fauna, which in Europe comprises some
thirty-five or more species, many, or most of them, of a distinctively
African type. The affinities with the tropical faunas are seen in
the development of the geckotine type (Hemidactylus verruculatus,
the common gecko of the houses of Southern Europe ; Gymno-
dactylus, Phyllodactylus, Platydactylus) and the agamas (Agama,
Stellio—South Russia and the Balkan Peninsula), the Old World
representatives of the American iguanas. One species of chameleon
(Chameleo vulgaris) is found in Andalusia.

In temperate North America lizards are even more scarce than
in the equivalent region of the Old World. Indeed, in the whole
of the continent north of a line that might be considered to unite
San Francisco with Galveston in Texas there are probably less than
twenty species, of which more than one-half belong to the Old
World genus of skinks, Eumeces. A distinctive feature separating
the saurian fauna of this tract from the European is the absence of
the group to which all the commoner European forms (Lacerta)
belong, although the genus Xantusia, from the Pacific coast, is by
some authors doubtfully referred to the Lacertide. On the other
hand, a distinct Old World relationship is established in the glass-
snake (Ophiosaurus—from Tennessee southward and westward), a
near ally of which is the glass-snake (Pseudopus) of Southern Eu-

LIZARDS. 317

rope (Dalmatia, Hungary, Russia) and West-Central Asia.* In the
region lying south of the San Francisco-Galveston line, which is
largely in the form of parched or desert tracts, the prevalence of a
considerable number of tropical or South American types imparts a
distinct individuality, or non-North American character, to the
fauna, which is best expressed in the family of iguanas (Iguanide).
This group is represented by not less than forty species, the greater
number of which belong to the genera Sceloporus and Phrynosoma
(‘‘horned-toad ”), one species of the latter genus penetrating as far
north as Dakota.¢+ Inhabiting the same tracts, but extending its
range to Tehuantepec, is the venomous Heloderma. A single spe-
cies of amphisbeenian, the ‘‘ thunder-worm” (Rhineura Floridana),
is known from Florida. The so-called chameleon of the Southern
United States is the green goitred lizard Anolis.

The more distinctive or most largely represented tropical fami-
lies of lizards are the iguanas, agamas, monitors, geckos, amphis-
beenians, and chameleons. The first of these is almost exclusively
American, and is represented by probably not less than three hun-
dred species, of which nearly, or fully, one-third belong to the
genus Anolis, whose members especially abound in the West India
islands. The genus Iguana is more properly South American, al-
though also found in some of the West Indies, and penetrating
northward into Mexico. Basiliscus, the basilisk, likewise ranges
into Mexico. In addition to the forms that have already been in-
dicated as belonging to the United States, may be mentioned Uta,
Callisaurus, and Holbrookia, the last of which is sufficiently abun-
dant in certain parts of Texas and the transition-region to the
northwest. The most remarkable member of the family is the
Galapagos leguan (Amblyrhynchus), which is partially marine in
its habits. Brachylophus inhabits the Feejee Islands. No iguanian

* A variety of this species also occurs in Morocco. M. Boulenger has re-
cently attempted to show (‘‘ Ann. and Mag. Nat. Hist.,”? Aug., 1885) that
the North and South American lacertiiian faunas are, strictly speaking, one,
the Neogean, a conclusion which is not borne out by the facts of distribu-
tion. The misconception arises from the incorporation of the tract lying
south of the line indicated above with the North American faunal region
proper, while in reality it is a transition-tract more nearly Neotropical in
character than ‘‘ Nearctic.’’

+ Phrynosoma orbiculare was found by Mr. Geddes on the plateau of
Mexico at an altitude of 7,500 feet.

318 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

is found on any of the continental divisions of the Old World, but
two genera of terrestrial habits, Hoplurus and Chalarodon, appear
in Madagascar.

The true Old World representatives of the iguanas are the
agamas (Agamidz), which might be said to present a parallel series
of forms to the iguanian types of the New World. Their distribu-
tion covers the greater part of the continent of Africa, the warmer
tracts of Asia, especially the islands of the East Indian Archipelago,
and much of Australia. No species has thus far been obtained
from New Zealand. A limited number of species is found in Asia
north of the Himalayas (Trapelus, Phrynocephalus— Tartary to
Afghanistan), and their occurrence in Southern Europe (Agama,
Stellio *) has already been noted. Several genera have representa-
tives in the Andaman and Feejee Islands groups. Among the more
remarkable forms of the family are the flying-lizards (Draco)—in-
habitants of the East Indies (except Ceylon)—which are provided
with a tegumentary expansion specially adapted for sailing through
the air; the frilled lizard of Queensland, Australia (Chlamydosaurus
Kingii), which is ornamented with a broad fan-like collar nearly
encircling the head and neck; and the spine-covered Moloch hor-
ridus of Southern and Western Australia. The agamas proper range
throughout Africa, and eastward to India.

The geckos (Geckotide), which, with the exception of the
cosmopolitan skinks, have the broadest distribution of all the
lacertilian families, number about two hundred species. They
occur in the hotter parts of all the continental regions, and are
largely represented even in the more distant oceanic islands—Ma-
deira, Ascension, the Seychelles, New Zealand; the Solomon, An-
daman, and Sandwich Islands groups, &c.—evidently possessing
some special means for dispersion which is wanting in other rep-
tiles. Several of the more largely represented genera, as Gymno-
dactylus, Phyllodactylus, and Hemidactylus, have practically the
range of the entire family; Gonatodes is found in tropical America
and East India, but is wanting in Africa. The genus Gecko, as
restricted, has about seven species, which are confined to China,
Japan, the Papuan Islands, and the islands of the East Indian
Archipelago. Most of the geckos are nocturnal in their habits,

* Boulenger (‘‘ Catalogue of Lizards,’ British Museum, 1885) considers
Trapelus and Stellio as synonyms of Agama.

LIZARDS. 319

and it would appear that the different species intentionally keep
apart from each other. Colonel Tytler observes that ‘although
several species of geckos may inhabit the same locality, yet, as a
general rule, they keep separate and aloof from each other; for in-
stance, in a house the dark cellars may be the resort of one species,
the roof of another, and crevices in the walls may be exclusively
occupied by a third species. However, at night they issue forth in
quest of insects, and may be found mixed up together in the same
spot; but on the slightest disturbance, or when they have done
feeding, they return hurriedly to their particular hiding-places.” "5
Remarkable instances of broad specific range are presented by Hemi-
dactylus mabouia, which inhabits Brazil, San Domingo, Eastern
Africa, and Madagascar, and Gehyra mutilata, whose range extends
from the Mascarene Islands through India, the Malay Peninsula,
and New Guinea to Mexico. With the exception of the common
chameleon (Chamzleo vulgaris), whose range extends from Anda-
lusia through North Africa eastward to India and Ceylon, all the
species of the family are restricted to the African continent and
the neighbouring islands (Madagascar, Bourbon, and Fernando
Po, the first with nearly one-half the total number of species).
The monitors, or water-lizards (Varanide), which range over the
greater part of Africa, East India, Australia, and the Austro-Malay-
an islands, comprise the largest Old World members of the class,
some of the species measuring, or exceeding, six feet in length.
The common monitor of the Nile (Monitor Niloticus) is found in
the neighbourhood of all the more important streams of tropical
Africa. Psammosaurus scincus, a North African species, is strictly
terrestrial in its habits.

The amphisbeenians, or footless lizards, which by Dr. Gray are
elevated to the rank of a distinct order, are principally tropical
American forms, although a considerable number of species are
known from the African continent, and a few, of the genus Blanus,
from the Mediterranean districts of Europe and Asia. In America
the species range from the Argentine Republic through the West
Indies to Florida (Rhineura [Lepidosternon] Floridana). Chirotes
lumbricoides, which is provided with the anterior pair of appen-
dages, is a Mexican species. A distinctively American family of
lizards is the Teiidw, or teguexins, which may be said to replace
the Old World Lacertidz, and whose range extends from Patagonia

320 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

to Montana and Virginia. Upwards of a hundred species have
been described.

New Zealand (or rather the small islands off the northeast coast)
possesses a remarkable lizard in the genus Hatteria or Sphenodon,
which in many points of structure departs from the type of true
lizards, and approximates it to an ancient lost form from the Trias,
the genus Hyperodapedon.

The earliest known representative of the Lacertilia is Protero-
saurus, from the Permian deposits of Germany and England, which
appears to be most nearly related to the monitors, from which,
however, it differs in its thecodont dentition.* Hyperodapedon
(which, with the contemporaneous Rhynchosaurus, and the recent
Hatteria, is by some authors constituted into a distinct order,
Rhynchocephala) and the acrodont genus Telerpeton (Elgin lime-
stones of Scotland) appear in the Trias, and are succeeded in the
deposits of Jurassic age by a number of more or less obscurely
defined genera (Geosaurus, Homeeosaurus, Acrosaurus, Anguisau-
rus), whose relationships with modern forms are in most cases not
clearly indicated. Lacertilian remains are not abundant in the Cre-
taceous deposits, and such as have been preserved are mainly in a
fragmentary condition; the recent genus Hydrosaurus, one of the
monitors, is indicated. In Tertiary strata the remains become nu-
merous, and belong in considerable part to modern types. Frag-
mentary skeletons from the European Miocene deposits have been
referred to Iguana and Lacerta, and, doubtfully, also to Scincus
and Anguis.—No true lacertilians are known from American de-
posits older than the Eocene. The western lake-basins of this age
have yielded numerous remains, which are referable to a number
of distinct genera—Glyptosaurus, Iguanavus, Oreosaurus, Tino-
saurus, Saniva—and some of which appear to have survived into
the Miocene. Among the very limited number of forms of this
period may be mentioned Peltosaurus, doubtfully referred to the
Gerrhonotide, and Cremastosaurus, the latter of about the size of
the horned-toad.

Ophidia.—The distribution of the Ophidia is very similar to
that of the Lacertilia, the order being most numerously represented

* Professor Seeley believes it probable that Protcrosaurus is a dinosaur.
(Phillips, ‘* Manual of Geology,” edited by Etheridge and Seeley, 1885.)

SERPENTS. 321

in the tropical regions of the earth’s surface, and rapidly diminish-
ing toward either pole. Excepting, however, members of the
family of water-snakes (Hydrophide), which are especially abun-
dant in the Australian and Indian seas—ranging westward to Mada-
gascar, and eastward to Panama—the order is only exceptionally
represented in the strictly oceanic islands, in this respect differing
from the lizards and agreeing with the amphibians. Evidently,
the animals of this class, like the Amphibia, possess no facilities
for traversing broad arms of the sea.

With our deficient knowledge of many of the more favoured
regions of the globe it is impossible to arrive at any estimate of
the numerical extent of the order, but it may be safely assumed
that there are considerably more than one thousand clearly defined
species known to naturalists, of which very nearly one-half are
found in British and Farther India, and the East Indian Archi-
pelago. Mr. Blanford places the number of species from British
India and its dependencies alone at two hundred and seventy-four.*
In Europe, north (and inclusive) of the Alps, there are some fifteen
or more species, of which three, the common viper or adder (Vipera
[Pelias] berus), the grass or ringed snake (Tropidonotus natrix),
and the Coronella Austriaca (levis), penetrate beyond the fifty-fifth
parallel of latitude. These are the only species found in Scandi-
navia, the British Isles, Denmark, Holland, and Belgium. The
most northerly of all serpents is the common viper, whose range
embraces the whole of Europe and Northern Asia, and which in
Scandinavia extends to the Arctic circle; in the Alps it is occa-
sionally met with at an altitude of nine thousand feet. The north-
ern limit of the ringed snake appears to be the sixty-fifth parallel.
Germany has in all six or seven species,"* the three above men-
tioned, and Tropidonotus tessellatus, Elaphis flavescens (Esculapii),
Zamenis viridiflavus (doubtful), and Vipera aspis (the asp), the last
very largely distributed throughout the whole of France and Switz-
erland, and the commonest of the venomous serpents of Italy. — It
does not appear to ascend the Alps to elevations much exceeding

* The census of the other Reptilia ig as follows: Chelonia fifty-four, Cro-
codilia four, Lacertilia one hundred and eighty-two. The Amphibia com-
prise about one hundred species, of which one only belongs to the tailed
division, and five to the Pseudophidia (Cecilia). ‘Journ. Asiatio Soe.
Bengal,’’ Dec., 1881.

322 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

five thousand feet. The species, like many of the other Mediter-
ranean forms, is found also in Algeria, but seems to be absent from
Morocco."7 All of the German species occur in Switzerland, which,
however, numbers one additional form, Tropidonotus viperrinus.

The Mediterranean fauna, or what might be considered to be
the fauna of Southern Europe, comprises about thirty species, in
which are included probably all the forms that occur elsewhere in
Europe; the Iberian Peninsula numbers twelve species, ™* Italy about
fifteen, and Greece fourteen."’ In the western half of this region
the similarity existing between the ophidian faunas of the several
countries amounts almost to identity, but eastward, from the Balkan
Peninsula to the Crimea, a gradual exchange of species is effected,
so that in both Turkey and Russia nearly, or fully, one-half of the
species (about fifteen in each country) are distinct. Somewhat more
than one-half of the Italian and Iberian species are also found in
the region south of the Mediterranean—Algeria and Morocco.

The North American serpents, or those found north of the
Mexican boundary, belong in the main to two families, the colubers
(Colubridz) and pit-vipers or rattlesnakes (Crotalide), the former
numbering some one hundred and ten or more species, and the
latter about twenty. In addition to these there are a limited num-
ber of representatives of three or four other families. Thus, the
worm or burrowing snakes (Typhlopide), whose species are abun-
dantly distributed over the tropical regions of both hemispheres,
occur sparingly in California and Texas (Stenostoma); the Erycide,
a limited family of Old and New World serpents allied to the boas,
are represented on the west coast by two species of Charina (Cali-
fornia to Puget Sound); and the venomous Elapida, to which very
nearly two-thirds of all the Australian snakes, and the deadly cobra
(Naja), Bungarus, and Ophiophagus of India belong, are repre-
sented by the harlequin-snake (Elaps fulvius) in the Southern United
States (east of the Mississippi), and by Elaps euryxanthus in Ari-
zona. The greater number of these forms can scarcely be said to
constitute a part of the North American ophidian fauna proper,
inasmuch as they occur principally in a border tract whose gen-
eral faunal relationship is more nearly with the region lying to the
south than the north.

The North American colubrine snakes are comprised principally
in five or six groups or genera: 1. Tropidonotus, water-snakes, whose

SERPENTS. 323

range is coextensive with the whole United States, and whose best
known exponents are the ribbon-snake (T. [Euteenia] saurita), water-
snake or adder (T. sipedon), and garter (T. [Eutzenia] sirtalis), the
first two abundant in the region east of the Mississippi, and the last
found almost everywhere from Canada and Nova Scotia to Mexico
and Panama. 2. Coluber, whose range is no less extensive than
that of the water-snakes, and which embraces among other forms
the most broadly distributed black-snake or constrictor (C. [Basca-
nium] constrictor) and the coachwhip-snake (C. flagelliformis) of
the Southern States. 3. Pityophis, pine-snakes. 4. Elaphis, to
which the spotted racer (E. [Scotophis] guttatus), chicken-snake (E.
quadrivittatus), and pilot (E. obsoletus) belong, the first two prin-
cipally from the Southern States, and the last generally distributed
over the Atlantic border, from New England to Alabama. 5. Ophi-
bolus, king-snakes, whose species are widely diffused throughout
the United States, and whose best known representatives are the
southern chain-snake (O. getulus)—with a western variety known
as the king-snake (O, Sayi)—the red-snake (O. doliatus), and the
very common milk-snake or spotted adder (O. triangulus), whose
range extends from the Atlantic border to the Mississippi, and
northward to Canada; and, 6. Diadophis, ring-necked snakes, rang-
ing nearly through the entire continent south of the Canadian line,
The genus Cyclophis comprises two common species of green-
or grass-snake, the summer-snake (C. wstivus) and spring-snake
(C. vernalis), both of which have a very extensive distribution.
Two species of hog-nose snake (Heterodon) occupy a considerable
part of the United States, and are locally known as blowing-vipers
or adders.

The remaining colubrine forms are embraced in genera largely
limited as to the number of species, and which in many cases, as in
Contia, Tantilla, Sonora, &c., are confined to the transition-tract
which unites with the Neotropical realm. The North American
crotaloids are comprised in three or more genera: Crotalus, the
rattlesnakes proper, Sistrurus (or Crotalophorus), the prairie or
grass rattlesnakes, which are confined principally to the Central
and Southern United States, and Ancistrodon, the copperheads and
moccasins. Of the last there are three species: A. contortrix, the
copperhead, whose habitat is the greater part of the region east of
the Mississippi; A. piscivorus, the true or water moccasin, which

824 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

inhabits the waters of the Southern States from South Carolina to
Texas; and A. atrofuscus, the highland moccasin, found in the
mountain-region south of Virginia, and by many authors considered
to be only a variety of the last. The rattlesnakes proper are repre-
sented by some ten or more species, most of which are found in
the region of the Southwestern United States. Five species (or
varieties) are known east of the Mississippi, of which the common
or banded rattlesnake (C. horridus), which is still abundantly dis-
tributed between Texas and New England, has the most extended
range. The diamond-rattlesnake (C. adamanteus) inhabits the
Southern States.

Although the greater number of species of North American non-
venomous Ophidia belong to genera or groups which are also largely
developed in, and are equally characteristic of, the Old World, as
Tropidonotus (Eutenia), Coluber (Bascanium), and Elaphis (Scoto-
phis), types but barely represented in the Neotropical realm—thus
clearly indicating the Old World affinities of the so-called ‘‘ Nearc-
tic” fauna, it appears that all the species are distinct.* This is not
very surprising in view of the limited northern range, especially in
the Western Hemisphere,t of the majority of the species, which are
incapable, and have been incapable for a long period past, of tra-
versing the chilled northern tracts by which at one time, doubtless,
a union was effected between the two hemispheres. As a result of
this isolation new species have been formed. It is more remarkable
that the most northern of all ophidian genera, Viperus, the viper,
whose appearance on the American continent might have been con-
fidently looked for as a result of its extended range, is completely
wanting. Other anomalies of distribution are presented by the
distinctively American genera Heterodon and Dromicus, both of
which have representatives in the island of Madagascar, and the
family of pit-vipers (Crotalids), which is largely developed in the
Oriental realm, but is wanting in Africa.

Of the more important families of tropical and sub-tropical

* By most American herpetologists Eutenia, Bascanium, and Scotophis
are considered to be distinct from the Old World genera with which they
have been united by the greater number of European naturalists.

+ Several species are found in British Columbia along the Canadian bound-
ary-line, but it is doubtful whether any penetrate much beyond the fiftieth
parallel of latitude.

SERPENTS. 325

snakes—indeed, of all snakes—the colubers take first rank, num-
bering probably fully one-fourth of all known species of Ophiilia.
They are, strictly speaking, the most cosmopolitan of all the vari-
ous groups, and are represented, in addition to genera whose dis-
tribution embraces several of the zoogeographical regions, by a
number of distinct genera in each of the great zoogeographical
regions except Australia, where the family is but feebly developed
(Tropidonotus, Coronella). Next in importance, and more strictly
tropical, are the venomous colubrine snakes (Elapidz), with probably
upwards of one hundred species, about one-half of which are con-
fined to Australia and the neighbouring islands. The family, which
is almost wholly wanting in the north temperate region—repre-
sented by the genus Callophis in Japan and by the harlequin-snakes
(Elaps) in the United States—comprises many of the most deadly
of the Thanatophidia, as the cobra (Naja tripudians), Bungarus,
and Ophiophagus of India and some of the eastern islands. Callo-
phis bilineatus appears to be the only poisonous snake of the Philip-
pines. The genus Elaps embraces all or most of the American
species of the family, including the much-dreaded Brazilian coral-
snake (Elaps corallinus).*

Partaking very nearly of the distribution of the last family are
the burrowing-snakes (Typhlopid), whose numerous members,
belongirg chiefly to the genus Typhlops, are found in nearly all
the warmer regions of the earth’s surface. One species of the
genus, Typhlops lumbricalis, is found in Greece and on some of
the Grecian islands. The tree-snakes proper (Dendrophide) are
found in all the tropical regions; the nocturnal tree-snakes (Dip-
sadid) and the arboreal whip-snakes (Dryiophide) are also essen-
tially tropical, but they are either wholly, or almost wholly, wanting
in Australia.

The boas or pythons (Boide; Pythonide) are one of the most
distinctively tropical families, comprising some fifty or more species.
The pythons proper (genus Python) are distributed throughout
ntarly the whole of the Oriental region—the islands as well as the

* Many travellers and naturalists, and notably Maximilian, Prince of Wied,
have denied the venomous nature ot this animal. The researches of Ihering,
however, conclusively demonstrate this nature in Elaps Maregravii, and would
seem, consequently, to uphold the common notion concerning E, corallinus
(‘‘ Zoologischer Anzeiger,’? August, 1881).

326 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

mainland—and over the greater part of the continent of Africa,
although by some naturalists the Ethiopian species are placed in a
distinct genus, Hortulia. The netted python (P. reticuldtus) in-
habits nearly all the islands of the Malay Archipelago, besides
portions of the mainland (Farther India), where it shares in part
the habitat of the common Indian species, P. molurus. Among
the African species are the royal python of the western forests
(P. regia), Seba’s python, or the fetich-snake (P. Seb), whose
distribution is much more general, and the Natal rock-snake (P.
[Hortuiia] Natalensis). The Australian Pythonide are included in
the genera Morelia, Aspidiotes, Liasis (islands of the Arafura Sea),
and Nardoa, to the first of which belong the diamond-snake (M.
spilotes) and the carpet-snake (M. variegata) of the colonists. In
the New World the pythons are replaced by the boas and anacon-
das, which by many naturalists have been constituted into a distinct
family, Boidse, and whose habitat is principally the warmer parts
of the South American continent. Boa constrictor, whose home is
more properly the equatorial forest region, is represented by several
closely allied forms in Central America and Mexico, as B. isthmica,
B. imperator, and B. Mexicana, which are by some autnorities con-
sidered to be mere varieties of the common southern constrictor,
and by others as distinct species. A fourth species, the yellow
boa (Chilabothrus inornatus), whose home is the West Indies, is
doubtfully said to inhabit Central America and Mexico as well.*
The anaconda (Eunectes murinus) is found in the tropical waters.
The most remarkable instance of a localised family of any ex-
tent is presented by the earth-snakes, or rough-tailed burrowing-
snakes, as they are sometimes called, the Uropeltid, whose thirty-
five or more species are confined almost entirely to Ceylon and the
southern part of the Indian Peninsula, or to the tract constituting
the Cingalese sub-region of the Oriental realm. Their headquarters
on the peninsula are the western mountain-ranges between Canara
and Cape Comorin, only one species, according to Beddome,® be-
ing found in the mountains of the east coast, and but three on the
west, whose range extends northward beyond Kudra Mukh in South
Canara. Several species of Silybura ascend the Neilgherrics to an
* The naturalists of the United States Fish Commission steamer ‘ Alba-

tross’? found a species of boeform serpent on the island of New Providence,
Bahamas (‘‘Science,’’ June, 1886).

CROCODILES. BY

elevation of seven thousand feet, and Plectrurus Perrotetii is found
between five thousand and eight thousand feet.

Fossil remains of serpents are not numerous, and only one spe-
cies, the Simoliophis Rochebruni, from the Upper Cretaceous de-
posits of the Charente, France, is known to antedate the Tertiary
period. Several species of Palzophis, considered by some authors
to have been closely related to the boas, which they rivalled in size,
and by others to constitute the type of a distinct family, have been
found in the Lower Eocene deposits (Londonian) of England, France,
and Italy; two or three species have been likewise described from
the nearly equivalent deposits of the State of New Jersey.* Bow-
form serpents appear to be indicated by the Python Eubaicus,
from Kumi, in the island of Eubea, and by the remains from the
Eocene fresh-water deposits of the Western United States which
have been referred to the genera Boavus, Lithophis, and Limno-
phis. The genus Coluber is represented by several species from
the Miocene fresh-water deposits of the continent of Europe (Oen-
ingen, &c.). Fossil Toxicophidia, or venomous serpents, appear
to be still less abundantly represented than the non-venomous
types. A form supposed to be related to the rattlesnakes has been
described from Salonica as Laophis crotaloides, and one, related to
the cobra, from Steinheim, as Naja Suevica. The most ancient
remains of Ophidia in the New World appear to be those of Hela-
gras prisciformis, from the Puerco Eocene, which was of about the
size of the black constrictor (Coluber constrictor).

The paucity of ophidian remains leaves very uncertain any specu-
lations as to the origin or evolution of this order of animals.
Whether or not they are in part the modified descendants of the
lacertilian pythonomorphs, which they seem to approximate in cer-
tain points of structure, still remains to be determined.

Crocodilia,—Of the four orders of existing reptiles the Croco-
dilia are numerically the least important, and at the same time the
most restricted in their distribution. Some twenty-five more or
less well-defined species, inhabiting the tropical and sub-tropical
regions of the earth’s surface, are known to naturalists, by whom
three distinct groups or families are recognised: the gavials, croco-
diles proper, and alligators. The gavials are exclusively Old World
forms, and the alligators forms belonging to the New World. The

* Paleophis littoralis, P. Halidanus, P. (Dinophis) grandis.

328 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

former, as understood by most systematists, are comprised in two
genera, Gavialis (with a single species, G. Gangeticus), restricted
to the waters of the Indian Peninsula, and Tomistoma, a Bornean
form, whose range probably extends to North Australia.

The true crocodiles, of which some authors recognise two gen-
era, Crocodilus and Mecistops,* inhabit nearly all the larger streams
(and many of the lakes) of Africa, India, and the north coast of
Australia. Although for a long time supposed to be entirely want-
ing in the New World, they are now known to inhabit the waters
of tropical America on both sides of the Andes (Ecuador, Colombia,
the Orinoco, &c.), extending their range to Mexico and the West
India Islands (Cuba, San Domingo, Jamaica). Crocodilus Ameri-
canus enters some of the streams of Florida. The species having
the broadest distribution appear to be Crocodilus porosus, whose
range embraces the area included between the North Australian
coast, the Indian Peninsula, and China, and C. vulgaris, the com-
mon African form, which is found throughout the greater part of
the continent, and which has been reported, although doubtfully,
also from Palestine. Two species of crocodile, C. robustus and C,
Madagascariensis, the one related to the common Indian form and
the other to the African, are found on the island of Madagascar.

The alligators (Alligator), also known as caymans and jacarés,
and comprising, according to some authors, not less than ten dis-
tinct species, are confined to the waters of tropical and sub-tropical
America, ranging from the Argentine Republic to Tennessee. The
single species of the United States is the Alligator Mississippiensis.
It is not a little surprising, seeing the presence there of crocodiles,
that alligators should be almost wholly absent from the West In-
dies; one species (A. latirostris) is said to inhabit the island of
Guadeloupe.

Geologically the crocodiles represent an ancient group, dating
their first appearance, as far as is yet known, from the Triassic pe-
riod. Three genera of this age are recognised: Stagonolepis, from
the Elgin sandstones of Scotland, Belodon, from Wirtemberg, the

* Dr. Gray, in his “‘ Catalogue of the Shield Reptiles of the British Mu-
scum”? (1872), makes seven genera, of which Oopholis is Asiatic and Austra-
lian, Bombifrons Asiatic, Palinia and Molinia American, and the remainder,
Crocodilus, Halerosia, and Mecistops, African. It is questionable whether
any of these forms is entitled to generic distinction.

CROCODILES. 829

Eastern United States, and India, and Parasuchus, from India. In
the deposits of the succeeding Jurassic age the number of distinct
types and species is very largely increased. No less than forty
species, beionging in the main to the genera Mystriosaurus, Teleo-
saurus, Steneosaurus, Metriorhynchus, and Dakosaurus, are known
from British strata alone.’ Many of these are also found in the
deposits of the continent of Europe, which comprise a considerable
number of additional types. The amphiccelous, or biconcave, type
of vertebra, distinctive of the Triassic and Jurassic crocodilians, is
retained in a measure by the Cretaceous forms, as in Goniopholis
and the American Hyposaurus,* but we now also meet, and for the
first time, with the type of the modern proceelian crocodile. Gavialis
and Crocodilus, abundantly developed as Tertiary forms, both oc-
cur in the Upper Cretaceous beds of Europe, and are represented
in the nearly equivalent American deposits by the gavialine genera
Holops and Thoracosaurus. Tomistoma is found in the Miocene
of Malta and Lower Austria. Alligator does not appear before the
Tertiary (Eocene) period (Europe and America). A gavialine form
from the Siwalik deposits of India, Rhamphosuchus crassidens, is
supposed to have attained a length of from fifty to sixty feet.

The origin of the crocodilian line is involved in much obscurity.
Whether or not the animals of this group stand in direct genetic
relation with some of the earlier labyrinthodonts, as is maintained
by some paleontologists, our present knowledge does not permit us
to determine. Among themselves, however, the different croco-
dilian types exhibit a remarkable gradational series of structural
peculiarities, which connect the most ancient and the modern forms,
and place them in an almost unbroken sequence. Professor Huxley
has indicated the line of succession as passing from the Parasuchia
—the Triassic forms, in which neither the palatine nor pterygoid
bones enter into the formation of secondary posterior nares—through
the Jurassic and Cretaceous Mesosuchia, in which the palatines
alone are produced to form these nares, to the modern and Upper
Cretaceous (proccelian) Eusuchia, in which both bones are similarly
produced. M. Dollo recognises in Bernissartia, a recently discov-

* Hyposaurus Rogersi, from the ‘‘ greensands”’ of the Eastern United
States, was until recently the only known species of the genus; a second

species, H. Derbianus, has been described by Professor Cope trom the Province
of Pernambuco, Brazil (‘‘ Trans. Am. Phil. Soe.,” Jan., 1886).

830 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

ered form from the Cretaceous deposits of Belgium, the ancestral
type of the short nosed modern crocodilians—z. e., the crocodile
and alligator.

BIRDS.

The principal features connected with the geographical distribu-
tion of birds having been discussed in the early part of this work,
only the geological distribution of the class will be considered here.

The earliest known birds are the Archeopteryx, whose remains
have thus far been found only in the Solenhofen limestone (Up-
per Oolite) of Bavaria, and the Laopteryx priscus, from a nearly
equivalent horizon of the Western United States (Wyoming Terri-
tory). The latter, which was of about the size of the great blue
heron (Ardea Herodias), is apparently a member of the hetero-
geneous group designated by Marsh the Odontornithes, or toothed-
birds, to which the more remarkable of the American (Middle)
Cretaceous birds, Ichthyornis, Hesperornis, and Apatornis, belong.
Ornithic remains, with somewhat doubtful relationships, and re-
ferred to the genera Graculavus, Laornis, Paleotringa, and Tel-
matornis, have also been obtained from a somewhat higher horizon
(Upper Cretaceous) in the Eastern United States (New Jersey).
Almost the only clearly determined bird-remains of this period
occurring in Europe are those of Enaliornis (Pelagornis; Upper
Greensand of Cambridge), which appears to have had some resem-
blance to a penguin.

In the Tertiary deposits remains of this class are very much
more numerous, and there is a close approximation to modern type-
structures. Thus, in the Eocene deposits of the Paris Basin and
elsewhere in France (Auvergne, Provence, Languedoc) we find the
remains of the true quail (Coturnix), grouse (Tetrao), cormorant,
godwit, rail, sandpiper, nuthatch, and falcon, associated with which
are a number of forms whose relationships have not in all cases
as yet been absolutely determined. The most remarkable of these
is probably Gastornis Parisiensis, a bird of about the stature of the
African ostrich, but possessing so many well-marked anatine char-
acters as to have induced some naturalists to class it with the
ducks and geese.* Agnopterus and Elornis appear to have repre-

* Gastornis Klaasseni, a bird apparently exceeding the ostrich in size, has

recently been described by Mr. Newton from the Lower Eocene strata of
Croydon, England (‘* Proc. Geol. Assoc.,’’ Feb., 1886).

BIRDS. ook

sented the flamingoes, and Paleocircus and Palzortyx, as is indi-
cated in their names, the raptorial and gallinaceous birds respec-
tively. It is not a little remarkable that Leptosomus, the type of
a small family now absolutely restricted to the island of Madagascar,
should constitute a part of thisfauna, The deposits of the Swabian
Alps have yielded a limited number of bird-remains (harrier, cor-
morant), and so have those of Glarus, Switzerland, whence was
obtained the nearly perfect skeleton of the passerine form known
as Protornis or Osteornis.

The equivalent, or nearly equivalent, deposits of the London
Basin, the island of Sheppey, and of Hempstead, in the Isle of
Wight, have also yielded a number of avian forms, some of which
appear to have been most intimately related to types now living,
such as the herons, gulls, and kingfishers (Halcyon or Halcyornis).
But here, as in the Paris Basin, there occur several distinct types
whose position among living forms it is very difficult or impossible
to establish. Such are the Megalornis, a bird somewhat smaller in
size than the emu; Dasornis, which apparently combines true
struthious characters with those of the recently exterminated moas
of New Zealand; Macrornis, also with struthious characters; and
the very singular anatine Odontopteryx toliapicus, recalling in its
dental armature the Cretaceous toothed-birds of America. All the
older Tertiary bird-remains that have thus far been described
from the American continent are from the Western United States,
and belong in principal part to the gruiform genus Aletornis (Wy-
oming), some of whose species appear to have attained to nearly
the stature of the sand-hill crane. A true owl (Bubo leptosteus),
about two-thirds as large as the great horned-owl (B. Virginianus),
represents the birds of prey, and the passerine Paleospiza bella the
songsters; the former is from Wyoming (Eocene), and the latter
from the insect-bearing shales of Florissant, Colorado (Oligocene ?).
A giant struthious bird, combining some of the characters of the
extinct moas, has been described by Professor Cope from the Eocene
deposits of New Mexico, as Diatryma gigantea, a form not un-
likely generically identical with the European Gastornis.

Ornithic remains are much more abundant in the Miocene de-
posits than in the Eocene, and there is a corresponding further
approximation to modern type-structures. From the lacustrine
deposits of Central and Southern France, whence the greatest

332 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

number of distinct types has been obtained, upwards of fifty spe-
cies have been described, the greater number of which are referable
to the modern genera Aquila (eagle), Haliaetus (fishing-eagle),
Milvus (kite), Bubo (owl), Picus (woodpecker), Corvus (crow),
Motacilla (wagtail), Passer (sparrow), Columba (pigeon), Rallus
(rail), Phoenicopterus (flamingo), Grus (crane), Ardea (heron), Ibis,
Totanus (tattler), Numenius (curlew), Tringa (sandpiper), Larus
(gull), Phalacrocorax (cormorant), Sula (gannet), Pelecanus, and
Anas (duck). The occurrence of a parrot (Psittacus) and of sey-
eral species of pheasant (Phasianus; also in Greece) is rather re-
markable, since the former is no longer an inhabitant of the
European continent, or of any adjoining tract, and the latter is
generally conceived to have been a modern introduction from
Asia. Several of the generic types found in France have also been
recognised in the deposits of South Germany (Steinheim, &c.).
The Siwalik Hills formation of India has yielded the remains of
two species of pelican, a cormorant, stork (Leptoptilus), merganser,
ostrich (Struthio Asiaticus) and emu (Dromeus? Sivalensis). With
reference to the occurrence in India of the last named bird, whose
relationship with its living Australian congener, Dromeus Nove-
Hollandie, is very intimate, Mr. Lydekker says: ‘‘The former
occurrence in India of a large struthioid closely allied to the emu
is one more instance of the originally wide distribution of the
struthioid birds; and it not improbably indicates that the home of
the group of which the cassowaries, emus, and moas are diverging
branches, was originally somewhere in the neighbourhood of the
Indian region, whence a migration took place during some part
of the Tertiary period towards the southeast, where the group, in
regions more or less completely free from the larger mammals, sub-
sequently attained its greatest development.” * The American
Miocene birds are limited to some four or five species, a turkey
(Meleagris antiquus ; Colorado), nearly as large as the common
wild species (M. gallopavo), gannet, shearwater, and guillemot.
The Pliocene and Post-Pliocene birds of the continent of Europe
are much less numerous than the Miocene, and in the greater num-
ber of cases do not admit of absolute determination. Several
species of waders, swimmers, and gallinaceous birds (Gallus, Scolo-
pax, Anas, Anser), more or less intimately related to existing forms,
have been described from England, France, and Germany. The

MONOTREMES. 333

mallard (Anas boschas) and grey lag-goose (Anser cinereus) both
appear to be represented in the later deposits. Among the cave
deposits of France have been discovered the remains of the snowy-
owl (Nyctea Scandiaca) and willow-grouse (Lagopus albus), north-
ern forms which appear to have followed the southward migration
of the reindeer, and of a large extinct species of crane (Grus primi-
genia). Two or more species of swan have been found in the os-
siferous cavern of Zebbug, in the island of Malta, one of which,
Cygnus Falconeri, an extinct form, exceeded by about one-third
the dimensions of the common C. olor.

Of the group of sub-fossil birds, or those whose remains belong
to a comparatively very recent period, are the giant struthious
birds of New Zealand, known as ‘‘moas” (Dinornis and Mionornis,
with some seven or more species), and the palapteryxes (Palapteryx
and Euryapteryx); the 4!pyornis maximus of Madagascar; and the
Australian Dromeornis australis, the precursor of the modern emu.
A giant goose (Cnemiornis), associated with which are the remains
of several remarkable ralline forms (Aptornis and Notornis—the
latter surviving up to our own period), and a number of other
birds, also occur in the newer deposits of New Zealand. In this
connection may be mentioned, although not strictly falling under
the category of fossils or sub-fossils, the recently exterminated
didine birds of the Mascarene Islands—the dodo (Didus ineptus)
of Mauritius, and the solitaire (Pezophaps solitarius) of Rodriguez;
the crested parrot of Mauritius (Lophopsittacus Mauritianus), and
the Aphanapteryx, an abnormal ralline species, from the same isl-
ands.

MAMMALIA,

Monotremata,—This, the most limited, order of terrestrial
Mammalia, forming the sub-class Ornithodelphia of most natural-
ists, comprises two families, the Ornithorhynchide, or duck-bills,
and Echidnide, or Australian hedgehogs, the former of which is
restricted to the continent of Australia and Tasmania, and the lat-
ter to the same region with the addition of New Guinea. The
duck-bills are represented by a single species, the platypus or water-
mole of the colonists (Ornithorhynchus paradoxus or anatinus).
No fossil remains referable to this genus have as yet been dis-
covered.

The Echidnide comprise two recent genera: Echidna, with

334 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

three or four more or less clearly defined species (E. hystrix or
aculeata, E. cetosa, E. acanthion*) inhabiting Australia and Tas-
mania, and a single one (E. Lawesii) New Guinea; and Acantho-
glossus, represented by A. Bruijnii, from Northern New Guinea.
Fossil remains of this family are not numerous, and belong exclu-
sively to the Post-Pliocene deposits of the Australian continent.
Echidna Oweni is founded upon a portion of a humerus from Darling
Downs, and indicates an animal considerably larger than the com-
mon recent species. E. Ramsayi, from a breccia cave in Wellington
Valley, is likewise founded upon a humerus.

Marsupialia,.—All the existing members of this order, if we
except the single family of American opossums (Didelphide), are
restricted to the Old World, and are in the main confined to the
Australian continent and New Guinea, a limited number of forms
finding a habitat in the debatable tract between the Australian and
Oriental realms. The general features of their distribution are
discussed in the chapter treating of the Australian realm. The
order. is not represented in either of the continents of Eurasia or
Africa.

The opossums comprise a considerable number of species, the
majority of which are confined to South and Central America;
two species, Didelphys Virginiana and D. Californica, are found in
the United States, the former, the common American species, rang-
ing from the Gulf border to the State of New York. An aberrant
web-footed form, the yapock (Chironectes), inhabits South and
“Central America.

Marsupial remains in deposits older than the Tertiary are not
abundant, and are in the main comprised in a number of genera
whose exact relationships have not as yet been absolutely deter-
mined. Indeed, it is not a little doubtful whether the earliest
forms usually referred to this order—those from the Trias—actually
belong here, or represent an even more primitive type of mammal.
To this category of uncertain forms may be referred the Microlestes
antiquus, from the Keuper of Germany, M. Moorei and Hypsiprym-

* Described by Collett from North Queensland (‘‘ Forh. Selsk. Christiania,”
1884). Liitken indicates the possible existence of a fourth Australian species
(‘* Proc. Zool. Soc.,’? London, 1884, p. 150), while Dubois defines a supposed
new species, named Proechidna villosissima, from New Guinea (‘‘ Bull. Mus.
Belg.,”’ iii., p. 109).

MARSUPIALS. 335

nopsis Rheeticus, from the Rhetic deposits of Somersetshire, Eng-
land, and Dromatherium sylvestre, from the Chatham coal-fields of
North Carolina. Of less doubtful affinity are Tritylodon, from the
Triassic deposits of ‘South Africa, and the numerous forms whose
fragments have been obtained from the British Oolites and the
island of Purbeck—Amphitherium, Phascolotherium, Stereogna-
thus, Spalacotherium, Amblotherium, Stylodon, Triconodon, Tria-
canthodon, Plagiaulax—and from the nearly equivalent deposits of
the Western United States (Diplocynodon, Stylacodon, Tinodon,
Triconodon, Dryolestes, Ctenacodon). Many, or most, of these
forms appear to depart to a certain extent from the normal type of
marsupial structure—approximating the Insectivora— hence, by
some naturalists, as Professor Marsh, they are relegated to distinct
groups—Pantotheria and Allotheria—supposed to have no living
representatives.* The Marsupialia are not represented in the Creta-
ceous deposits ; Meniscoessus, a form whose closest relationship
appears to be with the Jurassic Stereognathus, occurs (in associa-
tion with dinosaurian remains) in the Laramie formation of the
Western United States, the position of which in the geological
scale, as has already been intimated, is more properly with the
Cainozoic than with the Mesozoic series.

The Tertiary marsupial remains of the Northern Hemisphere
belong principally to the earlier periods, beginning with the oldest
Eocene; in Europe they have not been recognised higher than the
middle Miocene, and in North America, if we except the pygmy
opossum (Didelphys pygmea) from the Miocene of Chalk Bluffs,
Colorado, no representative is known from deposits newer than the
Oligocene (White River beds). Barring the opossums,t whose
earliest remains have been found in the Eocene deposits of both

* According to Professor Seeley, Hypsiprymnopsis, which appears to be
most intimately related to the modern kangaroo-rat (Hypsiprymnus), is founded
on the premolar teeth of Microlestes. The same authority recognises in Am-
phitherium and Phascolotherium a strong combination of marsupial and in-
sectivore characters, and the indications of a ‘‘ generalised insectivorous type,
modified from a monotreme stock in the direction of the marsupial plan”?
(Phillips’s ‘‘ Manual of Geology,” i., p. 520, 1885).

+ Separated by some authors from the genus Didelphys as Peratherium
and Amphiperatherium ; Peratherium, whose range extends into the Miocene,
is represented by five or more species in the White River deposits of Colorado,
the largest of which about equals in size the mole (Scalops aquaticus).

336 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

France and England, none of the recent families are indicated.
The herbivorous type seems to be entirely wanting in the European
deposits, but in America, the forms that have been described from
the Puerco formation of New Mexico as Polymastodon are re-
ferred to this type by Professor Cope. Neoplagiaulax, from the
basal Eocene beds of France and New Mexico, and its near ally
Ptilodus, represent the Jurassic Plagiaulacide, and appear to effect
a partial transition from these to the Pliocene or Post-Pliocene
Thylacoleo of Australia.

The remains of true kangaroos (Macropodidz), some of them,
as Palorchestes, considerably exceeding in size the largest of the
modern representatives of the family, occur in the newer Pliocene
or Post-Pliocene deposits of the Australian continent. Associated
with these are a number of remarkable forms whose precise affini-
ties still remain to be determined, although in the general character
of their dentition they approximate the kangaroos and phalangers.
Diprotodon australis, with less disproportionate limbs than in the
kangaroos, appears to have exceeded the rhinoceros in size. Of
somewhat smaller dimensions are the species of Nototherium.
Thylacoleo carnifex, described as ‘‘one of the fellest and most
destructive of predatory beasts,” is held by many naturalists to
have been an herbivore.

Edentata.—The animals of this order are at the present day
confined almost wholly to the southern continents—indeed, it might
be said principally to the continent of South America (with Central
America), which possesses more than three-fourths of all the known
species. Of the five recognised families, the sloths (Bradypodide),
ant-eaters (Myrmecophagid), and armadillos (Dasypodide), are
exclusively American; the aard-varks (with two or three species—
Orycteropus Capensis, the Cape ant-eater, O. &thiopicus, from
Northeast Africa, and a possible third species from Senegal) are
African; and the scaly ant-eaters or pangolins (Manidide), both
African and Asiatic. The species of the last, some eight or more,
are properly referable to a single genus, Manis, although several
sections, by some authors considered to be of generic value, have
been constituted to receive certain well-marked, but unimportant,
peculiarities of structure. The common pangolin (Manis penta-
dactyla) inhabits the Indian peninsula and the island of Ceylon,
sharing in part the distributional area of the Chinese species (M.

ANT-EATERS, ARMADILLOS. 337

aurita), whose range extends from North India to the island of
Formosa. The Javan pangolin is a native of Burmah, the Malay
Peninsula, and the larger islands—Java, Borneo, Sumatra—of the
Eastern Archipelago. A limited number of species are known from
Western Africa, one of which, M. (Pholidotus) gigantea, measures
about five feet in length to the tip of the tail. The most aberrant
form of the family is M. (Smutsia) Temminckii, from the southern
and eastern portions of the African continent.

Of the American groups the most restricted in point of numbers
are the ant-eaters, whose range, collectively, embraces the greater
portion of the Neotropical realm included between Mexico and
Paraguay, east of the Cordilleras. The better known species—in-
deed, the only species admitted by most authors—are the great ant-
eater (Myrmecophaga jubata), the tamandua (Tamandua tetradac-
tyla), and the little or two-toed ant-eater (Cycloturus didactylus),
whose individual ranges coincide largely with the range of the en-
tire family. The sloths, of which some authors recognise not less
than a dozen fairly well-marked species or varieties, occupy much
the same area as the ant-eaters, although they do not appear to
enter Paraguay. They are inhabitants of the forest region, which
limits their distribution. Two genera, founded upon the number
of toes on the fore-feet, are generally admitted : Bradypus, the
three-toed sloths, and Cholepus, two-toed’sloths, both of which
are very extensively distributed.*

The armadillos (Dasypodide), which comprise nearly twenty
clearly defined species, are the most broadly distributed of the
American edentates, their range extending from the most northern
limits of the Neotropical realm to the fiftieth parallel in Patagonia.
A single species, the peba or seven-banded armadillo (Tatusia
septemcincta), which is found in South America as far south as
Paraguay, enters the United States in Texas. Among the better
known species are the six-banded armadillo or encoubert (Dasypus
sexcinctus), an inhabitant of Brazil and Paraguay; the tatouay or
cabassou (Xenurus unicinctus), with much the same range as the
last, but extending into Guiana; the three-banded armadillo or

* Arctopithecus appears to have no distinctive generic characters. A
specimen of Bradypus tridactylus in the museum of the Royal College of
Surgeons, of London, corresponds, according to Professor Flower, with Gray’s
Arctopithecus gularis.

338 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

apar (Tolypeutes tricinctus), which, with the remaining members
of the generic group to which it belongs, has the power of rolling
itself into a complete ball; and the great armadillo (Priodon gigas),
an inhabitant of the forests of Brazil and Guiana, the largest living
representative of the family, measuring upwards of three feet from
the tip of the nose to the root of the tail.

Fossil remains of edentate animals are not numerous, and are in
the main confined to the Pliocene and Post-Pliocene deposits of the
New World, especially South America (Pampean formation of the
Argentine Republic; bone-caves of Brazil). The oldest known form
is Ancylotherium priscum, from the phosphorites of Quercy, France
(Oligocene), a generalised type of animal, considered by some au-
thors to stand intermediate between the Edentata and Ungulata; the
same genus (A. Pentelici) occurs in the Miocene deposits of Pikermi,
Greece. An apparently allied form, Macrotherium, whose remains
indicate a possible climber of gigantic proportions, with compara-
tively feebly developed hinder extremities, is represented by several
species in the Miocene deposits of both France and Germany. No
New World forms are known to antedate the middle Tertiary period.
Moropus, from the Miocene and Pliocene deposits of the Western
United States, comprises animals ranging in size between the tapir
and rhinoceros, but with uncertain affinities; equally uncertain is
the position to be assigned to the Pliocene Morotherium, whose re-
mains have been found at various localities in Idaho and California.

The South American edentate fauna (Pliocene and Post-Pliocene)
comprises, according to Gervais and Ameghino, some eighty or
more species, the greater number of which belong to genera now
no longer living. The better known forms are referable to the
families Megatheriide and Glyptodontide or Hoplophoride, the
former of which appear to hold an intermediate position between
the modern sloths and ant-eaters—combining the head and denti-
tion of the one with the trunk and appendages of the other—while
the latter, in the presence of a carapace, approach the armadillos.
Included in the family Megatheriidz, besides other forms, are the
genera Megatherium, with animals of the size of the rhinoceros,*

* Megatherium Americanum, from the Argentine Republic and Paraguay,
was only inferior in size to the elephant, far surpassing all other land animals.
A mounted skeleton measures eightcen feet in length from the fore part of the
head to the tip of the tail.

SEA—COWS. 339

Ceelodon, Mylodon, Lestodon, Scelidotherium, Plationyx, and Me-
galonyx, the majority of which embrace species of very robust
dimensions. The species are mainly found in the bone-caves of
Brazil, and in the Pampean and diluvial deposits of the Argentine
Republic and Patagonia. Megalochnus rodens, a diminutive spe-
cies, is from the island of Cuba. Nothropus priscus, from the
Argentine Republic, appears to have possessed arboreal habits, in
this respect agreeing more closely with the modern sloths than any
of the other forms. Of the North American members of this
family the best known species are Megatherium mirabile, a some-
what smaller form than the M. Americanum, from the superficial
deposits of the Southern United States ; Megalonyx Jeffersoni,
originally described from a cave in Virginia; and Mylodon Harlani,
from the Western and Southern United States. A peculiar genus
from the deposits of Natchez, on the Mississippi, has been described
as Ereptodon.

The glyptodons embrace a considerable number of Pampean
species, which by Burmeister and other authors are referred to sev-
eral distinct genera—Hoplophorus, Panochthus, Deedicurus, Eury-
urus, Glyptodon, and Schistopleurum. The best known species are
Glyptodon typus and clavipes.

Sirenia (Sea-cows).—This order is at the present day limited to
some half-dozen species, referable to two genera: Manatus, the ma-
natees, and Halicore, the dugongs, the former of which is common
to both the Eastern and Western Hemispheres, while the latter is
strictly confined to the Old World. Of the two American species
of Manatus the West Indian sea-cow (Manatus latirostris) inhabits
the creeks, lagoons, and estuaries of the north of South America,
the West Indies, and Florida, and the Brazilian sea-cow (M.
Americanus or inunguis) the South American coast-line to about
the twentieth parallel of south latitude, and the more important
Brazilian rivers, very nearly to their sources.* The only Old
World form (M. Senegalensis) inhabits the West African coast for
about ten degrees on either side of the Equator, and the interior as
far as, or farther than, Lake Tchad.

Of the three species of Halicore, one (Halicore tabernaculi) is

* The identity of the coast species and that of the Upper Amazon and Ori-
noco Rivers has not yet been absolutely established, but is considered highly
probable by Hartlaub (Spengel’s ‘‘ Zool. Jahrb.,’’ 1886).

340 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION,

restricted to the East African coast and the Red Sea, another (Hali-
core dugong) inhabits the Indian and Pacific oceans, eastward from
the home of the last to the Philippines, and the third (Halicore
australis) the waters of Eastern and Northern Australia.

Fossil remains of sirenians, although not very numerous, occur
throughout all the Tertiary formations, from the Eocene to the
Pliocene, inclusive. The earliest forms are the Eotherium Zgyptia-
cum and Manatus Coulombi, from the Mokattam limestone of Egypt,
Hemicaulodon effodiens, from the basal Tertiary beds of Shark
River, New Jersey, and the somewhat doubtful Halitherium du-
bium, from the deposits of the Gironde, France. In the last-named
genus are included a considerable number of species from the Mio-
cene deposits of Germany, France, Belgium, and Italy, and a single
undetermined (?) form from the Isthmus of Suez. Felsinotherium
and Chirotherium are Pliocene forms from Central and Northern
Italy, and Rhytiodus Capgrandi a species from the nearly equivalent
deposits of the Garonne, France. The American fossil sirenians
comprise, in addition to the Eocene Hemicaulodon, two or more
species from the Miocene deposits of South Carolina, Manatus an-
tiquus, M. inornatus, and Dioplotherium Manigaulti; the first also
occurs in New Jersey and Virginia. Of the Post-Pliocene forms .
the best known is the Rhytina gigas or Stelleri, ‘‘ Steller’s sea-
cow,” an animal which appears to have been fairly abundant about
Behring and Copper Islands as late as the second half of the last
century, but which is now apparently entirely extinct. The im-
bedded remains occur principally in the raised beaches and peat-
mosses of Behring Island.

Woodward calls attention to the significant fact that, if we
‘“‘take the belt of the tropics, that is, 284° N. and 234° §. of the
Equator (or, better'still, say 30° N. and 8. of the Equator), we shall
cover the geographical distribution of all the living sirenians. If
we take another belt of 30° north beyond the Tropic of Cancer, we
shall embrace the whole geographical area in which fossil remains
of sirenians have been met with. Assuming, as I think we may,
that the Sirenia at the present day belong exclusively to the tropi-
cal regions of the earth, and that Rhytina, in its boreal home, was
simply a surviving relic from the past (a sort of geological ‘ out-
lier,’ as of a stratum elsewhere entirely denuded away), we must
conclude that the presence of about twelve genera and twenty-

WIITALES. 341

seven species of fossil Sirenia, as widely distributed then as the
recent forms are at the present day, but with a range from the
Tropic of Cancer up to 60° of north latitude, affords a most valua-
ble piece of evidence (if such were needed) attesting the former
northern extension of subtropical conditions of climate which must
have prevailed over Europe, Asia, and North America, in Eocene
and Miocene times, and in the older Pliocene also.” '**

Cetacea (Whales, &c.).—The animals of this order are distrib-
uted throughout almost the entire oceanic expanse, and a limited
number of forms, the members of the family Platanistide, and
some delphinoids, are also found in fresh or estuarine waters.
Platanista Gangetica, an ighabitant of the waters of Northern India
—Ganges, Brahmaputra, and Indus, and their tributaries—is en-
tirely fluviatile, never being known to pass out to sea The only
absolutely fluviatile form occurring in America is Inia Geoffrensis,
from the Upper Amazonian water system; Pontoporia Blainvillii
inhabits the estuary of the Rio de la Plata, but is not positively
known to ascend that stream into fresh water.

Of the marine cetaceans two distinct types are usually recog-
nised by naturalists: the whalebone or toothless whales (Mystaco-
ceti), as represented by the right-whales (Balena), rorquals, or fin-
whales (Balznoptera), and the humpbacks (Megaptera), and the
toothed-whales (Odontoceti), which comprise the sperm-whales,
dolphin, porpoise, grampus, &c. The right-whales, which are
confined principally to the northern and southern seas, have been
divided into some half-dozen ‘species, which, however, so closely
resemble one another that not improbably they represent only vari-
etal forms of one and the same species. The best known is the
Greenland right-whale (Balena mysticetus) of the Arctic seas ;
other northern forms are B. Biscayensis and B. Japonica. The
southern species or varieties are B. australis, of the South Atlantic,
and B. antipodarum and B. Nove-Zelandia, of the South Pacific.
A nearly equal uncertainty attaches to the different varieties or
species of rorquals and humpbacks, especially the latter, some
forms of which are found in almost every sea. Four or more ap-
parently distinct types of rorqual inhabit the northern seas, but
whether these are absolutely separable from their antipodal con-
geners still remains to be determined. Much confusion exists as to
the synonymy of the species ; hence, the great difficulty of their iden-

342 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

tification. The members of this genus are probably the largest of
all living animals, some of the forms, as Baleenoptera Sibbaldii
and B. sulfurea, attaining a length of eighty or perhaps even a hun-
dred feet. The smallest of the known species of whalebone whales
is the rare Neobalwna marginata, from the Australian and New
Zealand seas, which attains a greatest length of about twenty feet.

Of the toothed-whales, other than the members of the family
Delphinidw (dolphins, porpoises, &c.), the best known and prob-
ably most widely distributed species is the cachalot or sperm-whale
(Physeter macrocephalus), a giant form measuring upwards of sixty
feet in length, whose habitat is more properly the tropical and sub-
tropical seas, the animal but rarely appearing in the polar waters.
More or less closely related forms of the same family (Physeteride)
are Kogia, Ziphius, and Mesoplodon, the species in each group of
which have either individually or collectively a very broad exten-
sion.* Two species of bottle-nose whale (Hyperoodon rostratus
and H. latifrons) inhabit the North Atlantic.

Of the delphinoid type of cetaceans the most numerously repre-
sented genus is Delphinus, the dolphin, or, as it is frequently mis-
called, porpoise, the numerous species of which are distributed
throughout most seas, a limited number even habitually ascending
some of the larger streams, as the Amazon. The type-form of the
genus is the common or Mediterranean dolphin, the hieros ichthys
or sacred fish of the ancients (D. delphis), which is also abundant
in the Atlantic, and of which closely allied, if not identical, forms
are found in the Australian seas (D. Forsteri) and in the North
Pacific (D. Bairdii).’** One of the most northerly species of dolphin
is the tursio, or nesarnak of the Greenlanders (D. tursio), which
inhabits the Atlantic between Greenland and the European shores.
Modifications of the ordinary delphinoid type are seen in the long-
beaked forms of the group Steno, and in a South Sea species, Leu-
corhamphus (Delphinapterus) Peronii, in which there is no dorsal
fin. The bottle-heads (Globicephalus) are inhabitants of nearly all

* Much diversity of opinion exists as to the number of species belonging to
the different genera. Thus, while Gray recognised not less than six species
of Kogia, founded upon about as many individual specimens, only one (Kogia
breviceps, found in the South and North Pacific oceans) is admitted by
Flower (“‘ Eneyel. Brit.,’’ 9th ed., xv., p. 396). The same authority likewise

considers the species of the other genera as being in great part founded upon
insufficient characters,

DOLPHINS, PORPOISES. 343

seas, especially the north and south temperate, and exhibit a marked
specific identity between the most widely removed forms (Australia
and North Atlantic). The type of the genus is the pilot-whale (G.
melas; Delphinus globiceps), the grindhval of the Faroe-Islanders,
whose distribution is practically coextensive with the northern seas.
Related to the preceding are the so-called grampuses of the genus
Grampus, of which only one species (G. griseus), remarkable for the
variability of its colouring, has been thus far clearly determined; it
inhabits the northern ocean, more rarely descending into the Medi-
terranean. A second form, from the Cape of Good Hope, has been
described as G. Richardsoni.

The true grampuses, also known as “killers,” from their preda-
cious habits, constitute the genus Orca, and are more nearly related
to the true porpoises than to the dolphins proper. They are dis-
tributed over the greater portion of the oceanic expanse, from Green-
land to Tasmania; but neither the relationships of the different so-
called species, nor the limitations of their respective habitats, have
as yet been determined. Orca gladiator, the common grampus, is
more properly a northern form, and is fairly abundant in the polar
seas. Pseudorca crassidens, a much rarer form of grampus, found
on the Danish coast, appears to be identical with a species from the
Australian waters. The genus Orcella is represented by two species,
one of which (O. brevirostris) inhabits the Bay of Bengal, and the
other (O. fluminalis), a fluviatile form, the Irrawaddy River, at a
distance of several hundreds of miles from its mouth.

Of the true porpoises of the genus Phoczna, whose limited
species are confined principally to the waters of the Northern
Hemisphere,* the best known and probably most widely distributed
form is P. communis, the common porpoise, which inhabits in
shoals or schools the North Atlantic, from Britain to Greenland
and the American coast, frequently ascending the outflowing
streams for a considerable distance above their mouths. They
have been observed on the Thames, at London, and appear to
have occasionally penetrated up the Seine as far as Paris. The
animal does not seem to enter the Mediterranean. By some natu-
ralists the common -porpoise of the Atlantic coast of the United
States is considered to be a distinct species, to which the name P.

* Phocena spinipennis has been described from the mouth of the Rio de
la Plata.

344 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Americana has been applied. <A peculiar form of porpoise, from
the Indian Ocean (?) and the Japanese coast, destitute of the dorsal
fin, has been described as Neomeris phoceniformis.

Of the remaining delphinoids the narwhal, or sea-unicorn (Mo-
nodon monoceros), inhabits the Arctic Ocean, rarely passing south
of the sixty-fifth parallel; the beluga, or white whale (Delphinap-
terus leucas), closely related to the last, is also an inhabitant of the
Arctic Ocean, descending on the American coast to the St. Lawrence
River, and more rarely, in European waters, to the shores of Scot-
land.

Excepting the Paleocetus Sedgwicki, from the boulder clay of
Roswell Pit, Ely, England, whose remains were encased in a matrix
supposed to be Upper Jurassic (Kimmeridgian), the earliest ceta-
ceans of whose organisation we know anything are the zeuglodons,
which apparently represent a type intermediate between the toothed
and toothless forms of the present day. They occur in the Upper
Eocene deposits (Jacksonian) of the Southern United States; one
species (Zeuglodon Wanklyni) has also been discovered in the
equivalent Barton sands of England, and two, corresponding to the
American forms—Z. macrospondylus and Z. brachyspondylus—in
the deposits (Eocene or Oligocene) of Birket-el-Keroun, Egypt.*
Closely related in dental characters to the zeuglodons, but differing
in well-marked cranial features, are the squalodons, whose remains
are abundantly scattered throughout the Miocene and Pliocene de-
posits of many parts of continental and insular Europe (Vienna
Basin, France, Antwerp and Suffolk Crags, &c.). They have also
been noted from nearly contemporaneous strata in North America
(Squalodon Atlanticus, from Shiloh, New Jersey t) and Australia.

The oldest known form of modern-type cetacean is Baleenoptera
Juddi, from the Oligocene (Headon) beds of the Hampshire basin,
England; no other representative of an existing genus has thus far
been found to antedate the Miocene period. Both the toothed and

* Dames suggests that the two forms of Miller may only represent the
male and female of a single species, which would then be the Zeuglodon
cetoides of Owen (‘‘ Sitzungsb. Berl. Ak.,”’ 1883).

+ The forms described from the Eocene deposits of the Ashley River, South
Carolina, are considered by Van Beneden and Gervais to be only doubtfully
referable to this genus.

INSECTIVORA. 345

toothless whales are represented in the deposits of this age (Mio-
cene), the latter, however, apparently only by the rorquals or their
immediate allies (Balenopters); Cetotherium seems to have occu-
pied a position intermediate between the Mystacoceti and Odonto-
ceti. Of the latter the earliest representatives appear to have been
the genera Ziphius and Mesoplodon, although not improbably the
true dolphin was an immediate contemporary. The baleen whales
proper are not known before the Pliocene, when, in addition to
Balena, and possibly Neobalzna, we meet with a number of extinct
types more or less closely related to these—Balenula, Idiocetus,
Plesiocetus. Balwnotus, from the Antwerp Crag, is a connecting
form between the baleen whales and the rorquals, and Bartinop-
sis between the rorquals and humpbacks. Cetacean remains are
abundant in the Post-Pliocene deposits, and comprise a variety of
recent types; the narwhal has been indicated from the deposits of
England and Siberia. The Miocene deposits of the Eastern United
States have yielded a number of delphinoid remains to which the
generic names Priscodelphinus, Tretosphys, Zarachis, Lophocetus,
Rhabdosteus, and Ixacanthus have been applied.
Insectivora,—The animals of this order, which comprises barely
more than one hundred and thirty to one hundred and forty living
species, of which about one-half are true shrews (Soricidz), are
distributed over the greater part of the earth’s surface, but are
absent from both South America and Australia. The greater num-
ber of the nine generally recognised families are limited to com-
paratively narrowly circumscribed distributional areas, which in
some cases are only co-extensive with the sub-regions or provinces
of the main zoogeographical divisions. The Guleopithecide, or
flying-lemurs, which were formerly referred to the true lemurs,
and by some naturalists to the bats, are the most aberrant forms of
the order, and constitute the type of a distinct sub-order, Insecti-
vora dermoptera. But two species are known, Galeopithecus volans
and G. Philippinensis—the former an inhabitant of the forests of
the Malay Peninsula, Sumatra, and Borneo, and the latter of the
similar districts of the Philippine Islands. The squirrel- or tree-
shrews (Tupaiide), small arboreal insectivores resembling squirrels
in outline and habits, are restricted to the Oriental region, where
they range from the Khasia Hills, in India, to Java and Borneo.

Of the two genera, Tupaia and Ptilocercus, the latter contains but
16

346 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

a single species, the very interesting Bornean pentail (P. Lowii),
remarkable for its long quill-shaped tail.—The elephant-shrews
(Macroscelidx), small leaping animals furnished with a trunk-like
snout, are confined principally to South Africa; a single svecies of
Macroscelides, to which genus the greater number of species belong,
is found north of the Atlas Mountains. Several fossil forms, appar-
ently referable to genera belonging to this family (Oxygomphus,
Parasorex, Echinogale), have been described from the Miocene de-
posits of France and Germany. Likewise restricted to the African
continent are the potamogales and golden-moles (Chrysochloridz)
—the former, represented by a single species (Potamogale velox),
inhabiting the territory about the Gaboon River, and the latter the
region south of the Equator, but more particularly the Cape of
Good Hope districts. Neither family is known by fossil repre-
sentatives. The Centetide occupy two widely separated regions
of the earth’s surface, namely, Madagascar, with the adjoining isl-
ands (possibly introduced into Mauritius and Réunion) and the two
larger islands of the Antilles, Cuba and Hayti. Most of the forms,
with the genus Centetes itself, the Madagascar hedge-hog, occupy
the former region; the American species (two) belong to the genus
Solenodon, which in certain anatomical points differs so essentially
from its nearest allies as to constitute in the opinions of some sys-
tematists"* the type of a distinct family, Solenodontide.

Of the three remaining families of insectivores, the shrews
(Soricid), moles (Talpide), and hedge-hogs (Erinaceid), the
first, which, as has already been stated, comprise about one-half
of all the species of the order, have the broadest distribution,
embracing, in fact, the entire tract covered by the Insectivora gen-
erally. By some naturalists but a single genus (Sorex), apart from
the very remarkable web-footed Nectogale from Thibet, is recog-
nised, which is differentiated into a number of more or less well-
marked sub-genera, founded upon the number and colour of the
teeth, and the bristles on the tail—Crocidura (Old World), Sorex
(the entire range), Blarina (Canada to Costa Rica), Neosorex, and
Crossopus, the last two amphibious forms of the New and the Old
World respectively. Several species referable to the genus Sorex
(and Crocidura) have been described from the Miocene formations
of France, and similar remains occur in the Quaternary cavern de-
posits and breccias of both Europe and Asia. One or two extinct

- HEDGE-HOGS, MOLES. 347

genera or sub-genera, Mysarachne and Plesiosorex,* have also been
incicated (Miocene).

The hedge-hogs comprise two genera, Gymnura and Erinaceus
(the hedge-hog proper)—the former of which inhabits the Malay
Feninsula and some of the islands of the Indian Archipelago, and
the latter, with about nineteen species, the greater part of Europe,
Asia, and Africa, although wanting in Madagascar, Ceylon, Bur-
mah, Siam, the Malay Peninsula, and the Archipelago. The range
of the common European species, Erinaceus Europeus, extends
from Ireland and the Shetland Isles (possibly introduced) to East-
ern China, and from the sixty-third parallel of latitude in the
Scandinavian Peninsula to Southern Italy, Asia Minor, and Syria,
ascending the Alps and Caucasus to elevations of 6,000 and
8,000 feet respectively. In view of this very remarkable range,
its absence from the New World is not a little surprising. Re-
mains of several species of hedge-hog have been found in the
Miocene deposits of France and Germany, but none of the recent
species, except E. Europzeus, which forms part of the Quaternary
cave fauna, are known as fossils. The genus Neurogymnurus,
which is probably closely related to Gymnura, is represented by a
single species (G. Cayluxi) in the French Eocene.

The moles are generically the most numerous of the Insectivora,
although the number of species is comparatively limited. The
greater number of the ten or twelve recognised genera are repre-
sented by but one or two species. The family belongs almost ex-
clusively to the Holarctic region, through which it is very generally
distributed, only a very limited number of species passing beyond
the confines of that region into the Oriental tract. The moles
proper (Talpa), with about four species, are found throughout
nearly the whole of the Eurasiatic tract, the range of the common
species, Talpa Europea, extending from Britain to Japan, and
from Scandinavia and Siberia to Italy and the southern slopes of the
Himalayas. The-water-moles (Myogale) are comprised in two spe-
cies, one of which, M. Pyrenaica, inhabits the northern valleys of
the Pyrenees, and the other, M. Muscovitica, the region of the
Don and Volga rivers. The American moles belong in principal
part to three genera: Condylura (the star-nosed mole, which in-

* Referred by Trouessart to the Talpide (‘‘Catalorue Mamm. Viv. et
Foss.,’? 1881).

348 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

habits the Atlantic slope from Nova Scotia to South Carolina, and
westward to Oregon), Scapanus, and Scalops, the last (Scalops
aquaticus) the common American form, whose range covers the
greater part of the North American continent east of the Rocky
Mountains. A somewhat aberrant form, Neurotrichus Gibbsii,
found in the Western United States (Cascade Mountains to Texas),
has its analogue in the Urotrichus of Japan, to which genus it has
generally been referred, and from which it differs mainly in the
dental formula.—Fossil remains of Talpide date back to the Eo-
cene period (Prototalpa, Quercy, France ; Talpavus, Wyoming),
but the genus Talpa itself is not known prior to the Miocene; the
common European species is found in the Quaternary deposits.
Myogale (with Paleospalax and Galeospalax) occurs in the Miocene
and Pliocene deposits of France and England respectively. None
of the existing American genera have as yet been found in a fossil
state. Other insectivorous forms, however, known principally in
a fragmentary condition, and not impossibly referable, at least in
part, to the type of insectivorous Marsupialia, have been described
from the Eocene of Wyoming and New Mexico (Passalacodon,
Centetodon, Entomodon, Entomacodon, Triacodon, Esthonyx), and,
together with a number of Miocene forms from Dakota and Colo-
rado (Leptictis, Isacis, Ictops), constitute a distinct family, Lep-
tictide.

Insectivorous Forms of Doubtful Position.—Numerous insec-
tivorous animals, known largely by portions of their dental armature
alone, are found in the older (principally Eocene) Tertiary deposits
of France and the western territory of the United States (Wyoming,
New Mexico). They are not improbably, as Professor Cope sug-
gests, referable in part to the lemurs, although from their imperfect
state of preservation it is in many or most cases impossible to de-
termine their true relationship, whether with the class of animals
just mentioned or with the true insectivores. By Trouessart they
are all ranged with the Insectivora as the group of the protolemurs.
Among the better known of these forms are Microsyops, Palseaco-
don, Hyopsodus, Sarcolemur, Tomitherium, Notharctus, Necro-
lemur (supposed by Filhol to have its nearest ally in the galago of
Africa), Adapis (Paleolemur), and Protoadapis, the last three from
the Eocene of France, and representing distinctively lemuroid types.
Galerix is from the Miocene deposits of the same country. In the

BATS. 349

North American lower Eocene genus Anaptomorphus (A. zemulus
and A. homunculus), which comprises animals of about the size of
the ground-squirrel (Tamias), and whose dentition approximates
that of the higher apes and man, Professor Cope recognises the
most simian type of lemur yet discovered, and believes that it
‘represents the family from which the anthropoid monkeys and
men were derived. Its discovery is an important addition to our
knowledge of the phylogeny of man.” ”*

Cheiroptera (Bats).—Bats are practically of world-wide dis-
tribution, being found almost everywhere over the continental
tracts where there is a sufficient supply of insect food. The number
of species is very much- greater in the region of the tropics than in
the temperate zone—probably three times as great—the specific and
individual diminution corresponding to a marked elevation of lati-
tude being very rapid. Vesperugo noctivagans alone among the
American bats appears to reach the fifty-fifth parallel, but in Eu-
rasia one or more forms (Vesperugo borealis) penetrate to the
Arctic circle. Most of the species inhabiting the region of ele-
vated mountain-chains do not seem to ascend to any very great
altitude, preferring to remain in the basal zone of from 4,000 to
6,000 feet; a few instances are noted of habitation at nearly twice
this height. Vesperugo montanus and Molossus rufus have been
observed on the Peruvian Andes (Huasampilla) at an elevation of
9,000 feet; Vespertilio muricola on the Himalayas at 8,000 feet;
and Vespertilio oxyotus on the slopes of Chimborazo at nearly
10,000 feet. Vesperugo maurus is in Europe found chiefly in the
region of the higher Alps.

Bats, differing from all other mammals, are found in most of
the oceanic islands, but none have so far been observed in either
Iceland, St. Helena, the Galapagos, Kerguelen Land, or the islands
of the Low Archipelago.”’ Three species inhabit the Bermudas—
Vesperugo noctivagans, Atalapha cinerea, and Trachyops cirrhosus
(the last a vampyre *)—but only a single one the Azores—Vesperugo
Leisleri. It would thus appear that the members of this order of
animals were specially endowed with the power of crossing broad
arms of the sea, standing, in this respect, next to the birds. It is
more than probable, however, that, in the case of the species in-

* An individual of Molossus rufus, var. obscurus, is catalogued by Dob-
son as coming from Bermuda,

300 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

habiting the last two named island groups, their appearance there
is an accidental circumstance, depending upon the prevalence of
certain storm-winds by means of which an unlooked-for transport
has been effected; and even in the case of the species found in the
Pacific islands, it is not exactly unlikely that the broad distribu-
tion has been brought about in a manner not necessarily indicating
sustained flight, or at a period when the physical configuration
of that portion of the earth’s surface—the relation of land to water
—was different from what it is at the present day. For, as Mr.
Dobson suggestively points out, if the ‘t Cheiroptera possess great
powers of dispersal, it is certain that quite nine-tenths of the spe-
cies avail themselves of them in a very limited degree indeed,
and it is significant that the distribution of the species is limited
by barriers similar to those which govern it in the case of other spe-
cies of mammals.” * Thus, it is shown that out of a total of some-
what more than four hundred recognised species only about twenty-
five pass beyond the confines of the regions to which they properly
belong—i. e., about ninety-five per cent. are characteristic regional
forms; and of this number more than two-thirds belong to the pre-
eminently wandering family Vespertilionide, which has by far the
broadest geographical distribution of any family of the order. If,
however, it be urged that this restriction is not so much due to any
inability on the part of the animals to migrate, but to considerations
connected with altered conditions of food and climate—the influence
of which must be very marked—we have the still more salient fact
presented that of the numerous flying-foxes (Pteropus) which in-
habit Madagascar and the Comoro Islands, not a single species is
found on the east coast of Africa, the narrow channel of one hun-
dred and eighty to two hundred miles which intervenes between
the continent and Great Comoro Island seemingly being sufficient
to form an effectual barrier to a westward migration. Still, in this
special instance we are, perhaps, not presented with a just criterion
of the actual powers of dispersion possessed by this class of ani-
mals, since the slow and laboured flight of the large flying-foxes
can scarcely be compared with that of the smaller insectivorous
species; indeed, there is a striking similarity between the insectivo-
rous bat fauna of Africa and Madagascar.

Instances of very broad specific distribution among the Cheirop-

* ** Rept. Brit, Assoc.,’? 1878.

BATS. 351

tera are numerous, and perhaps most notably so in the case of the
genus Vesperugo, of the family Vespertilionide. Vesperugo noc-
tula, the noctule, is distributed throughout the greater part of the
Old World, from England to Japan, and from the Scandinavian
peninsula to Southern Africa; it extends through India to Ceylon
and the islands of the Malay Archipelago. Vesperugo abramus,
whose home is primarily the Oriental region, extending from Japan
to Northern Australia, is found during the summer months through-
out Middle Europe, and even as far north as Sweden; the species
furnishes us with a remarkable example of a true migrant. The
range of V. maurus extends from the Canary Islands (Palma, Tene-
riffe) through Central Europe (Switzerland, the Tyrol) to China and
Java, and that of Miniopterus Schreibersii from Southern Europe
(Spain, Italy) to Japan and the Philippine Islands, and throughout
the whole of Africa (with Madagascar) eastward to Australia. The
last is probably the most widely distributed of all known species
of bats, with the exception of the little serotine (Vesperugo sero-
tinus), whose distributional area covers nearly the whole of Eurasia,
Northern and Central Africa, and, in the New World, the American
continent from Lake Winnipeg to Central America, and the West
Indian islands. This is the only species that has been thus far
positively identified as being common to both the Eastern and
Western Hemispheres.* Of the strictly American species Atalapha
Noveboracensis, in its several varietal forms, appears to be the
most widely distributed, ranging from the Aleutian Islands to
Chili.

Of the six families into which the Cheiroptera have been divided
only two, the Vespertilionide and the Emballonuride, are common
to both the Eastern and Western Hemispheres; the former com-
prise some one hundred and sixty or more species, fully three-
quarters of which are confined to the Old World, over which they
are very extensively distributed. This is the most broadly dis-
tributed of all the families, and is that which has the most north-
erly range. Of its sixteen or more genera, at least five of which
—Antrozous, Nycticejus, Atalapha, Natalus, and Thryoptera—are
peculiar to America, only two, Vesperugo and Vespertilio, the

* Vesperugo abramus is thought by Dobson to be possibly identical with

a species (Scotophilus hesperus of Allen) from Vancouver’s Island (‘ Cat.
Cheir. Brit. Mus.,’’ p. 229).

352 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

former with about fifty species, and the latter with about forty,
approach cosmopolitanism. Of the Emballonurid but a single
genus, Nyctinomus, is common to both hemispheres, and its early
differentiation is shown in the fact that, while all the American
forms are closely related to one another, they depart widely from
their European representatives.

The Phyllostomide, or simple leaf-nosed bats, which comprise
the vampyres, number upwards of fifty species, all of them very
closely related, and, with one exception—Trachyops cirrhosus, which
has been noted from the Bermudas (and also doubtfully recorded
from South Carolina)—confined to the Neotropical realm, over the
forest-covered tracts of which they range from Mexico to about the
thirtieth parallel of south latitude.* Vampyrus spectrum, the best
known species of vampyre — whose habits appear to be mainly
frugivorous—and the largest of all the American bats, is distributed
over the greater portion of the tract covered by the entire family.

Of the strictly Old World families of bats the Pteropodide,
fruit-eating bats or flying-foxes, are specifically the most numerous,
comprising about seventy species, distributed between the Aus-
tralian, Oriental, and Ethiopian realms, and some of the intervening
tracts, with a preponderance of species in the first-named region.
They are restricted almost wholly to the region of the tropics,
where a continuous supply of tree-fruits might be obtained; no
species has thus far been noted from either New Zealand or Tas-
mania. Cynonycteris, alone of the genera, has the distribution of
the entire family. The most largely represented genus is Pteropus,
which includes more than one-half of all the recognised species be-
longing to the family; its range extends from the Comoro Islands
on the west to the Navigators’ Islands, in the Pacific, on the east,
and through much the greater portion of the Oriental and Aus-
tralian regions ; but few of the island groups of the Pacific—
Sandwich Islands, Low Archipelago, Gilbert’s and Ellice’s groups
—are deficient in the members of this genus, to which the largest
known forms of bats belong. Pteropus edulis, which inhabits the
islands of the Malay Archipelago, measures five feet in expanse of
wing. Only one species, Pteropus medius, the common flying-fox,

* Macrotus Californicus or Waterhousii just enters the United States (Fort

Yuma, California), but at a point which more properly belongs to the Neo-
tropical than to the Holarctic tract.

BATS. 353

has thus far been obtained from the Indian peninsula, and this, sin-
gularly enough, is more nearly related to the Madagascan P. Ed-
wardsii than to any of the more eastern species, although separated
from its habitat by a continuous water-way of upwards of one
thousand miles. The rarity of species in the Indian peninsula is
not readily accounted for, seeing how numerous are the individuals
belonging to the single species of the genus. *

Of the two remaining families of bats, the Nycteride and Rhino-
lophide, the former, comprising some twelve species, are almost
wholly restricted to the Oriental and Ethiopian realms, while the
latter, numbering about fifty species, are spread over the greater
portion of the Old World, from Ireland eastward to Japan and
New Ireland, and southward to the Cape of Good Hope. No spe-
cies appears to have been thus far positively identified from any of
the Polynesian islands. Nearly all the species are included in the
genera Rhinolophus and Phyllorhina, the former of which has prac-
tically the range of the whole family ; Rhinolophus ferrum-equi-
num, the common horseshoe bat, is distributed over almost the
entire tract included between the south of England, Japan, and
the Cape of Good Hope. The species of Phyllorhina are confined
principally to the tropical and sub-tropical parts of the Old World;
Phyllorhina armigera, the most northerly species, has been found
at Amoy, China, and at Mussoree, on the Himalayas, at an eleva-
tion of five thousand feet.

* Dr. J. Anderson thus describes the appearance of these animals (‘‘ Cat.
Mamm. Ind. Mus.,’’ 1881, p. 101, Part I): ‘‘ This species has been flying for
the last few days from the north to the south of the city [Calcutta] in im-
mense numbers, immediately after sunset. The sky, from cast to west, has
been covered with them as far as the eye could reach, and all were flying
with an evident purpose, and making for some common feeding-ground. Over
a transverse area of two hundred and fifty yards as many as seventy bats
passed overhead in one minute; and as they were spread over an arca of
great breadth and could be detected in the sky on both sides as far as could
be seen, their numbers were very great, but yet they continued to pass over-
head for about half an hour. This is not the first time I have observed this
habit in this species; indeed, it was more markedly secn in August, 1864,
while I was residing in the Botanical Gardens, Calcutta. The sky, imme-
diately after sunset. was covered with this bat, travelling in a steady manner
from west to east, and spread over a great expanse, all evidently making
for one goal, and travelling, as it were, like birds of passage, with a steady
purpose.”’

854 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Fossil remains of Cheiroptera, although of rare occurrence, are
found as far back as the upper Eocene, from the deposits of which
period a limited number of forms, representing in the main modern
genera, have been described. The oldest known forms are Ves-
perugo Parisiensis, much resembling the broadly distributed sero-
tine, from the gypsum of Montmartre, Vespertilio Morloti from the
nearly equivalent deposits of Switzerland, and Vespcrugo velox,
V. priscus, and Nyctilestes serotinus from the United States. In
this family of placental mammals alone do representatives of exist-
ing genera extend to such an ancient epoch as the Eocene. A
species of Rhinolophus, R. antiquus, has been described from the
phosphorites of Quercy, France—usually referred to the Oligocene
period—while a generically related form, Palwonycteris, occurs in
the Miocene. The Miocene deposits of both France and Germany
also contain several species of the genus Vespertilio, Post-Pliocene
or late Pliocene cave-remains closely approximate the forms now
living in the equivalent or adjoining region. The early specialisa-
tion of this class of animals, concerning whose differentiation prac-
tically nothing is known, indicates a most ancient line of ancestry,
which must be traced far into the Mesozoic era.

Rodentia.—With the exception of the bats the rodents are the
only order of terrestrial mammals which can be said to have a
nearly universal distribution, being found in all the primary zoo-
geographical regions but the Polynesian. On the continent of
Australia, however, only a single family, that of the mice (Muridz),
is represented, and that by a comparatively limited number of spe-
cies; the squirrels have a few representatives in the Austro-Malay-
sian transition-tract.

Of the four great divisions into which the rodents are divided,
the myomoryhs, or mouse-forms, are numerically much the most
important, the family of mice alone comprising considerably more
than one-third of the total number of species—some eight hundred
or more—belonging to the order. The geographical distribution
of this family is practically coextensive with that of the order.
The mice proper (Mus), of which there are upwards of one hundred
species known, are restricted exclusively to the Old World, over
which they are very extensively distributed; they are almost wholly
wanting in the Pacific and the greater number of the Austro-Malay-
sian islands, but are found sparingly in both Australia and New

RATS, MICE. 355

Guinea. Tasmania has several species, and one or more forms (M.
Novze-Zelandiz, M. Maorium) appear also to be indigenous to New
Zealand; M. Salamonis inhabits the island of Ugi, in the Solomon
group. The better known members of the group, the Norway or
brown rat (Mus decumanus), and black rat (Mus rattus), whose origi-
nal home seems to have been Southern or Central Asia, and the com-
mon mouse (Mus musculus), probably a native of India, have been
spread through man’s intervention over the greater portion of the
inhabited globe, rapidly displacing in many quarters the indigenous
races of similar or allied forms that originally occupied the con-
quered territory. The black rat, which appears to have been the
earliest intruder, is now largely supplanted by the brown species;
in England there would appear to be but a single colony left.* The
wood-mouse (Mus sylvaticus) and harvest-mouse (M. minutus), the
latter the smallest of the European species of mice, are distributed
over the greater portion of Europe and Northern Asia. The largest
member of the rat tribe is the great bandicoot or pig-rat of the
Indian penizsula (Nesokia bandicota), which frequently exceeds
one foot in length. Other distinctive rat-like forms of the Old
World are the spiny-mice (Acanthomys), which are confined prin-
cipally to Syria (Palestine), and the east coast of Africa; the jump-
ing-mice (Meriones or Gerbillus) of the continent of Africa, the
warmer tracts of Southern and Southwestern Asia, and the steppe
region about the Caspian Sea ; and the jumping-rats of Australia
(Hapalotis), which recall in general appearance the jerboas.

The Old World forms of the genus Mus are represented in the
New World by the vesper-mice (Hesperomys), which very closely
resemble them in general character, but differ in certain peculiari-
ties of dental structure, which likewise serve to distinguish most
of the American rats; some seventy or more species and varieties
have been described, ranging collectively from the Arctic regions
to the Strait of Magellan. Hesperomys leucopus, the white-footed
or deer mouse, inhabits the greater portion of the North American

é * While in most regions where the black and the brown rat have been in-

troduced the latter has been rapidly driving out or exterminating the for-
mer, it would appear that in some parts of Central Germany the reverse phe-
nomenon is presented—that is to say, the black rat is regaining its ascendancy
over the brown species (Magnus, “‘ Sitzungsber, d. Gesell. naturf, Freunde,”
1883, p. 47).

856 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

continent. The wood-rats, constituting the genus Neotoma, are
the largest of the American murine forms, and inhabit the greater
portion of the region included between Guatemala and Canada.
The cotton-rat (Sigmodon hispidus) is confined principally to the
Southern United States, Mexico, and Central America, occasionally,
it appears, wandering into the northern portions of South America.
In the genus Reithrodon are included a limited number of remarka-
ble leporine forms, which, though differing very essentially in gen-
eral appearance, do not seem to be distantly removed from the
North American harvest-mice of the genus Ochetodon; they are
confined principally to the extremity of the South American con-
tinent and to Tierra del Fuego.—Interesting modifications of struct-
ure or habit are seen in some of the murine forms, as in the par-
tially web-footed water-rats of the Australian region (Hydromys),
and in their Brazilian analogues of the genus Holocheilus; again,
in the arboreal dormouse-like forms that have been referred to the
genera Dendromys (Ethiopian) and Rhipidomys (American).

Of the less murine or rat-like forms of the mouse family the
voles or meadow-mice (Arvicolx), which in a measure replace the
true mice in the far north, and on elevated mountain-summits, and
whose distribution embraces nearly the whole of temperate and
Arctic Eurasia and North America, are probably the most nu-
merous specifically, while in point of individual numbers they far
exceed any other mammal, with the possible exception of the
closely related lemming. Many of the species enjoy a very broad
distribution, but none are known to be common to both the Eastern
and Western Hemispheres. Arvicola arvalis or agrestis, the com-
mon meadow-mouse, which ascends the Alps to a height of 7,000
feet, is distributed over nearly the whole of Europe (including
Italy) and Siberia, its range corresponding approximately with that
of A. amphibia (water-vole); A. alpina or nivalis inhabits the re-
gion of the higher Alps, between 5,000 and 12,000 feet elevation;
on the Finster-Aarhorn it has been observed at an altitude of 4,000
metres. The most broadly distributed of the American species is
the common meadow-mouse (A. riparia), whose range extends from -
the Atlantic to the Pacific, and from the Carolinas to the Hudson
Bay territory. A single species, A. quasiater, is known from Mex-
ico, Evotomys rutilus, a form very closely related to the arvicoles,
inhabits the circumpolar regions of both hemispheres.

HAMSTERS, LEMMINGS, DORMICE. 357

The hamsters (Cricetus) inhabit the greater portion of Europe
and Central and Northern Asia, the range of the common species
(C. frumentarius or vulgaris) extending from the Rhine to the Obi,
and from the Obi and Irtish souchward to Persia and the Caucasus;
other species inhabit the elevated steppes of Mongolia. Pouched
rats allied to the hamsters (Cricetomys, Saccostomus) are also found
in various parts of Africa. The lemmings, which are readily dis-
tinguished from the field-mice by the hairy covering on the soles
of the feet, and their sickle-shaped claws, are the most strictly
northern forms of all Rodentia.- The better known species are the
Scandinavian or Norwegian lemming (Myodes lemmus), the Si-
berian lemming (M. Obensis), which inhabits the boreal regions of
both hemispheres, and the Hudson Bay lemming (Cuniculus tor-
quatus or Hudsonius), an inhabitant of Arctic America, Greenland,
and corresponding latitudes in the Eastern Hemisphere; it is also
found in Nova Zembla.

A strictly American genus of Muride is Fiber, of which the
only recognised species is the musk-rat (F. zibethicus), whose range
embraces practically the whole of North America. A closely re-
lated, but considerably smaller, form is the recently described Neo-
fiber Alleni, from Brevard County, Florida. Of the non-murine
families of myomorphs the dormice (Myoxide) and mole-rats
(Spalacide) belong to the Old World exclusively, the pouched
rats (Saccomyide) are American, and the true jumping-mice or
jerboas (Dipodide) both Old and New World forms. The dor-
mice are scattered over the greater portion of temperate Eurasia,
from Britain to Japan, and southward over almost the whole of
Africa; they appear to be wanting in the warmer parts of Asia
(India). The common northern species, Muscardinus avellanarius,
is more generally replaced in the south by Glis vulgaris, the ‘‘seven-
sleeper” of the Germans, whose range extends eastward to the
Volga River and Georgia. Of the mole-rats, which are confined
almost wholly to the African continent and the tracts comprised in
the Oriental region, only a very limited number of species (Spalax)
pass within the European boundaries, and these are restricted
largely to the southeastern districts (Southeast Russia, Greece,
Hungary). Bathyergus maritimus, the-‘‘ great rodent-mole,” in-
habits the sand dunes of the Cape coast of Africa. The distribu-
tion of the distinctively North American family of pouched rats

858 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

has already been adverted to in the general treatment of the North
American fauna. The jerboas or true jumping-mice are distributed
from the eastern confines of the Mediterranean to India, and south-
ward over nearly the whole of Africa. Alactaga jaculus extends
its range westward from the Altai Mountains to the Danube, and
Dipus sagitta from the far east of Mongolia to the Volga. The
largest representative of the family is the Cape jumping-hare (Pede-
tes Caffer), whose range extends from Mozambique and Angola to
the southern extremity of the African continent. Only one trans-
Atlantic species is known, the American jumping-mouse (Zapus
Hudsonius), which is distributed over almost the whole of the
North American continent between Labrador and Mexico.

Of the squirrel forms, or sciuromorphs, the family of squirrels
(Sciuride), which comprises, in addition to the ordinary and flying-
squirrels, also the marmots and prairie-dogs, embraces very nearly
all the species belonging to the group. The true squirrels (Sciurus),
of which there are probably not less than one hundred species, are
extensively distributed over all of the continental divisions of the
globe with the exception of the Australian, being limited only or
primarily by a deficiency in the forest growth. The headquarters
of the genus might be said to be the Oriental region, which holds
nearly one-half of all the recognised species; no species are known
from either Madagascar or the West Indian islands, although sev-
eral forms inhabit the larger islands of the Malay Archipelago—
Java, Borneo, Sumatra, and Celebes.

In the whole of Europe, excluding the Caucasus, there is but a
single species of squirrel, Sciurus vulgaris, whose range extends
from the extreme north to the Mediterranean, and eastward through-
out Siberia. In the Engadine it ascends the A!ps to an elevation of
7,000 feet. North America north of the Mexican boundary possesses
six species (and about an equal number of well-marked varieties de-
pending upon size and colouration), of which the most familiar form
is the common chickaree (Sciurus Hudsonius), in its several varieties
—eastern chickaree, western chickaree, Fremont’s chickaree, and
Richardson’s chickaree—whose range extends from the northern
limit of forest vegetation to the highlands of Georgia and Alabama;
on the Atlantic border its southern limit appears to be Delaware Bay.
This is the only species of squirrel found north of the Canadian
boundary. The flying-squirrels are usually separated into two dis-

SQUIRRELS, MARMOTS, 309

tinct groups—the flat-tailed forms (Sciuropterus), which are abun-
dantly distributed over the northern parts of the North American
continent, and whose range in Eurasia extends from Lapland to
China and Java; and the round-tailed forms (Pteromys), constitut-
ing a more southerly group, whose home is the wooded districts of
tropical Southeast Asia, Japan, and some of the Malaysian islands.
By some authors the separation into two generic groups is not
recognised. The spermophiles or pouched marmots (Spermophilus)
and ground-squirrels (Tamias) are spread over the greater portion
of the temperate and boreal regions of the Northern Hemisphere,
but find their greatest numerical development in the New World.
The former, which in a measure connect the true marmots with
the squirrels, although sufficiently abundant in the far north of
Siberia and on the most elevated slopes of the Caucasus (S. musi-
cus), appear to be wanting in the Alps. The American species
occupy the western portion of the continent, ranging from the
Arctic seas to the plains of Mexico; none are found east of the
central plains or prairies. Of the ground-squirrels there are some
four or five recognised species, all of which are represented in North
America; the northern ground-squirrel or chipmunk (Tamias Asi-
aticus) is common to both the Eastern and Western Hemispheres,
ranging in America from Lake Superior and Arizona to the Barren
Lands, and in Eurasia from Saghalien and Japan through Siberia
to the Dwina River. In the eastern portions of the American con-
tinent this species is replaced by the common chipmunk or striped
squirrel (Tamias striatus).

The marmots (Arctomys) are restricted to the middle and north-
ern portions of the Northern Hemisphere, and comprise some ten
or more species, three of which are American. Of the last the
best-known form is the woodchuck (A. monax), whose habitat ex-
tends from the Carolinas to the sixty-second parallel of latitude,
and from the Atlantic border to Minnesota. Of the two European
species the bobac (A. bobac) is more properly an Asiatic form,
ranging from Kamtchatka to the German frontier. The true mar-
mot, the Murmelthier of the Germans (A. marmota or Alpina),
inhabits the mountain-tracts of Southern Europe—Pyrenees, Alps,
Carpathians—between elevations of 5,000 and 10,000 feet. The
American ‘‘ prairie” or ‘‘barking dogs,” more properly marmots
(Cynomys), of which there are two species known, appear to be

360 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

restricted to the parks and plains of the Rocky Mountain plateau
region.

The remaining sciuromorphs comprise the sewellels (Haplodon),
leporine rodents, somewhat of the habit of the musk-rat, inhabit-
ing the Northwestern United States; the singular anomalures from
Western Africa, which, in the possession of a lateral cutaneous
expansion adapted to aerial sailing, recall the flying-squirrels;
and the beavers (Castorid), of which the only species (Castor
fiber or Canadensis) inhabits the northern parts of both the East-
ern and Western Hemispheres. In its American home the beaver
is still met with in tolerable abundance west of the Mississippi
in the entire tract included between Alaska and Mexico; to
what extent its range extends into the last-named country has
not yet been ascertained. East of the Mississippi it is now but
sparingly found south of the Great Lakes, a limited number being
still harboured in the Maine and Adirondack wildernesses, and a
still smaller number probably finding their way along the thinly
settled districts southward to Alabama and Mississippi. In some
portions of Virginia and Pennsylvania they appear to be still fairly
numerous. The present range of the beaver in Europe is even
more restricted than in America, the animal being almost wholly
confined to Russia (and Poland), specially the streams of the Ural
Mountains and those emptying into the Caspian Sea, and, in iso-
lated colonies, to the Rhone, Weser, Elbe, and Danube rivers.
The animal is now extinct in Great Britain, and appears, also, to
have completely disappeared from Scandinavia.

The hystricomorphs embrace a number of families whose repre-
sentatives depart widely from one another in many essential char-
acters ; their greatest development is in the Neotropical realm,
which alone possesses the chinchillas, the agoutis, and the cavies,
besides the greater number of the partially Ethiopian family of
spiny-rats (Echiomyide). The best-known representative of the
last is the coypu (Myopotamus coypu), a large beaver-like animal
found only in Chili, measuring nearly two feet in length. Of scarcely
smaller dimensions is the arboreal Capromys pilorides, indigenous
to Cuba, where it constitutes the largest native mammalian. Pla-
giodontia eedium, a member of the same family, also found in San
Domingo, appears to be the only indigenous mammal of the island of
Jamaica, except the bats and mice (the latter probably introduced).

CHINCHILLAS, AGOUTIS, PORCUPINES. 361

The chinchillas comprise a limited number of species which are
restricted to the Alpine zones of the Peruvian and Chilian Andes
(the true chinchillas, C. lanigera, 8,000 to 12,000 feet; Alpine vis-
cachas, Lagidium Peruanum, 10,000 to 16,000 feet), and the pampas
between the Rio Negro and the Uruguay (true viscachas, Lagosto-
mus trichodactylus). All the agoutis and cavies (or Guinea-pigs)
are, as has already been stated, restricted to the Neotropical realm,
over which (principally east of the Andes) they are very extensively
distributed. The range of the agoutis proper (Dasyprocta) extends
from Mexico to Paraguay, one species (D. cristata) finding its way
into some of the smaller West Indian islands—St. Vincent, Santa
Lucia, Grenada; the paca (Czlogenys paca), the largest member of
the family, inhabits the river-bottom forests over almost the entire

“tract covered by the remainder of the species. The cavies proper
(Cavia) are spread throughout nearly the whole of the South
American continent, from Guiana to the Strait of Magellan, and
from the lowlands to the plateau region of perpetual snow; one
or more doubtful species are said to occur west of the Andes.
Brazil is most favoured as to number of species, from one of which
(Cavia aperea) appears to have descended the domestic Guinea-
pig. The Patagonian cavy .(Dolichotis Patagonica), an animal
measuring nearly three feet in length, inhabits the plains between
Mendoza and the forty-ninth parallel. The capybara (Hydrocherus
capybara), the largest of all living rodents, inhabits the whole of
South America east of the Andes and north of the Rio de la Plata,
wherever water is found; its range at one time appears to have ex-
tended as far south as the Salado, or even farther.

Of the remaining hystricomorphs the porcupines, of which some
authors recognise two distinct families, the true porcupines or por-
cupines of the Old World (Hystricide) and the tree-porcupines, or
the species of the New World (Cercolabidz), comprise a consider-
able number of forms, which though closely related to one another
in point of anatomical structure, affect most diverse conditions of
habit. The American species range from the northern limits of
trees to Paraguay, but the South American forms are generically
distinct from those inhabiting North America (except Mexico).
Two well-marked varieties of a single species, the Canada porcu-
pine (Erethizon dorsatus), inhabit the forest region of North
America. The eastern porcupine, or Canada porcupine proper.

362 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

whose range formerly extended southward to Virginia (and pos-
sibly also to Kentucky), is now largely restricted to its northern
habitat, although it is still found in certain portions of the State
of Pennsylvania. According to Dr, Allen it is but rarely met with
in New England south of Central Maine and Northern New Hamp-
shire. The western variety (E. dorsatus, var. epixanthus) occupies
the western half of the continent, ranging between Alaska and the
Mexican frontier. The greater number of the South American
species are included in the genus Cercolabes, tree-porcupine, whose
combined range extends from Paraguay to Mexico; Cheetomys sub-
spinosus inhabits the warmer parts of Brazil. Of the Old World
forms the best known is the crested or common porcupine (Hystrix
cristata), whose home is the Mediterranean districts of both Europe
and Africa, with some considerable reaches of territory also in the
western part of the latter continent. In South Africa this species
is replaced by Hystrix Africze-australis, and in India by the hairy-
nosed porcupine (H. leucura), which is found from the Himalayas
to the extreme south of the peninsula. Other species of the genus
Hystrix and of the brush-tailed porcupines (Atherura) are distrib-
uted over the Oriental realm from Nepaul to Borneo; a species of
atherure is also found in Western Africa.

The last division of the rodents, the rabbit-forms or lagomorphs,
embraces the rabbits or hares, and the pikas (Lagomys), small
Guinea-pig-like animals which are restricted almost wholly to the
elevated mountain districts (11,000 to 15,000 feet) of Northern and
Central Asia, with a single species found in Southeastern Europe,
and another, Lagomys princeps, in the Rocky Mountain region of
the Western United States and Canada. The rabbits and hares
(Lepus) include some twenty or more species, which are almost
entirely confined to the Northern Hemisphere, where they occupy
very nearly the whole of North America and Eurasia, and also
Northern Africa. A single species (Lepus Brasiliensis) is found in
South America, while several are known from South Africa, al-
though in the vast interior of the last-named continent the genus
does not appear to be represented. The distribution of the prin-
cipal American species has already been discussed in the general
consideration of the North American fauna. Only one of these,
the polar or Arctic hare (Lepus glacialis or timidus), whose range
extends over Greenland and the Barren Grounds to the Arctic

HARES. 363

coast, is common to the Old World, where its range extends
over the greater portion of Europe, from Scotland to the Ural
Mountains and the Caucasus. Singularly enough, the species ap-
pears to be wanting in Scandinavia. The variable hare (L. vari-
abilis), which is by many authors considered to be identical with
the last, or at best only a varietal race, inhabits Eurasia (from Ire-
land to Japan) north of the fifty-fifth parallel of latitude, but reap-
pears on the more elevated mountain regions of the south where
the climatic conditions are approximately those of the northern
lowlands. Thus, we find the animal in the Swiss, Bavarian, and
Austrian Alps, in the Pyrenees, and in the Caucasus, although in
much or most of the intervening lowland it is completely wanting.
Unlike the last species, which in the Alpine region occupies prin-
cipally the basal tracts, rarely ascending above 5,500 feet,* the
variable hare more properly frequents the elevated summits, up to
10,000 feet or more, and only occasionally descends below the level
of 4,000 feet. The species is wanting in the Jura Mountains. Much
uncertainty attaches to the true home of the semi-domesticated rab-
bit (Lepus cuniculus), which is at the present time so extensively
distributed throughout Europe, and the contiguous parts of Asia
and Africa, Until recently supposed to have been introduced
from Spain, the discovery of its remains in the Quaternary depos-
its north of the Alps would seem to throw considerable doubt upon
the accuracy of this hypothesis.

The most complete analysis of the extinct rodent fauna of the
Northern Hemisphere is furnished by Schlosser (‘‘ Paleeontograph-
ica,” 1884), who recognises about seventy well-characterised species
from the Tertiary deposits of Europe alone. Of these the most
ancient, or those of the Eocene and Oligocene periods, belong in
principal part to types that are either entirely extinct or have their
nearest analogues among forms living at the present day in tropical
America, Such are the genera Nesokerodon, Theridomys, and
Protechimys, from the French phosphorites, the first of which ap-
pears to be closely related to the South American cavies, and the
last two to the spiny-rats, and more distantly to the chinchillas.
The squirrels and dormice are represented by the modern gen-

* Théobald affirms the presence of the common hare at an altitude of 7,000
feet in the Grisons (Fatio, ‘‘ Faune des Vertébrés de la Suisse,’’ p. 250).

864 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

era Sciurus and Myoxus respectively, while Plesiarctomys presents
us with an ancestral form of the true marmots. Among the extinct
genera we find some remarkable suggestions of marsupial structure ;
thus, Pseudosciurus and Sciurodon, in the character of their den-
tition, approach the Australian koala (Phascolarctos cinereus), and
Sciuroides recalls the phalangers and the kangaroo-rats (Hypsi-
prymnus).

The Miocene rodents, principally represented in France and
Germany, although still retaining a number of the older types, as
Theridomys, show a much closer approximation to the modern
fauna. Among living genera we find (in the newer deposits) repre-
sentatives of the true squirrels, dormice, porcupines, and pikas or
tailless hares (Lagomys). The rabbits or hares (Lepus) are en-
tirely wanting, as, indeed, they are from the whole of the Euro-
pean Tertiary series, and likewise the true mice (Mus), if we ex-
cept the single species, Mus (Acomys) Gaudryi, from Pikermi,
Greece. The genus Cricetodon, whose earliest appearance is in
the Oligocene deposits of France, was without doubt the near
ally of the hamsters (Cricetus). One or more species of marmot
(Arctomys) have been indicated as belonging to the Miocene de-
posits of both France and Germany, but it is a little doubtful
whether the horizons whence the remains were obtained have
been correctly identified. _Arctomys primigenia, from Eppelsheim,
is not improbably a comparatively recent species, and not impos-
sibly identical with either A. marmotta or A. bobac. The most
abundant forms of this period are Myolagus Meyeri and Steneofiber
Jiigeri, both from the Upper Miocene of Germany and France, the
last replacing the more modern true beavers (Castor), Of the
older Miocene genera Archzomys stands intermediate between the
still earlier Protechimys and the chinchillas, and Issiodoromys be-
tween Nesokerodon and the cavies. The Pliocene rodent fauna
does not differ essentially from the Upper Miocene, of which it
may be considered to be a mere amplification. The recent genera
occurring here are already in the main represented in the period
preceding, although a limited number of new types, such as the
beaver (Castor Issiodorensis, possibly identical with the recent
Castor fiber; Puy-de-Déme, France) and the Arvicolide, are for
the first time introduced. The forms related to the South Ameri-
can fauna have, on the other hand, completely disappeared from

‘ELEPHANTS. 365

the continent. The remains of the existing species of porcupine
and beaver (cave of Gailenreuth) are found in the Quaternary
deposits.

The rodent fauna of the American (western) Tertiaries is very
closely related to the European, a large number of identical, or
analogous, genera being represented. This is especially the case
with the forms belonging to the Miocene period, where, in addi-
tion to a considerable number of extinct types, we find such forms as
Steneofiber, true beavers (Castor—several species), squirrels (Sci-
urus), vesper-mice (Hesperomys), and not impossibly also the true
porcupine (Hystrix). Eumys does not appear to differ essentially
from Cricetedon, while Ischyromys represents Sciuromys. A dis-
tinctive feature separating the American from the European fauna
is the introduction of the hares, which are not only represented by
forms now no longer living (Paleolagus), but also by the modern
genus Lepus. In the Pliocene fauna there is a still further approxi-
mation to the fauna of the present day in the appearance of an
additional number of recent genera—Erethizon (Canada porcupine),
Geomys (gopher). The last genus is also found in the Quaternary
deposits, as also other members of the same family (Saccomys), and
the vole, musk-rat, wood-chuck, ground-squirrel, wood-hare (Lepus
sylvaticus), beaver, and a form of capybara (Hydrocherus sopi).
Castoroides Ohioensis, the largest of all known rodents, recent
or fossil, appears to have been of the dimensions of the black
bear.

Proboscidea (Elephants).—At the present day there are but
two living species of this order known—the one being the Asiatic
elephant, Elephas Indicus, which inhabits the forest lands of In-
dia and Southeast Asia generally, with the islands of Ceylon, Suma-
tra, and (?) Borneo, and the other the African elephant, E. (Loxodon)
Africanus, a native of the greater part of the continent of Africa
south of the Sahara. The insular Asiatic form is by some authors
considered to represent a distinct species, to which the name E.
Sumatranus has been applied. Although now restricted in a gen-
eral way to the warmer parts of the earth’s surface, there can be
no doubt that the range of the species was very much greater at an
earlier period of the earth’s history than it is at present, seeing
how very broad was the distribution of the genus. The remains
of elephants undistinguishable from the African form have been

366 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

discovered in the Post-Pliocene deposits of Algeria, Sicily, and
Spain.

The extinct species of elephants are numerous, and their re-
mains are largely distributed over the continents of North America
(Alaska to Mexico) and Eurasia. None date back in time beyond
the Pliocene period, if we except the forms from the Siwalik de-
posits of the peninsula of India and the island of Perim, whose
horizon is somewhat doubtfully placed by geologists as Mio-Plio-
cene. The best-known species is the mammoth (Elephas primi-
genius), which was very closcly related to the Indian elephant, and
whose range covered the greater part of Northern Eurasia (extend-
ing as far south as Santander in Spain and Rome in Italy) and
Northwest America. Its remains are found most abundantly along
almost the entire Arctic shore of Siberia. The species belongs ex-
clusively to the Post-Pliocene period, and was doubtless contempo-
raneous with man in many of the regions inhabited by it. Other
well-known and somewhat earlier species are the European E.
antiquus and E. meridionalis, and the American E. Americanus.
Elephas Melitensis, from the island of Malta, is the smallest known
species, barely exceeding three feet in height when adult ; by
Pohlig it is considered to represent only a diminutive variety of
E. antiquus.

The closely related genus Mastodon antedates the true elephants
by one period, appearing in Europe in the Middle Miocene (Plio-
cene in America).* Its extinction in the Old World appears to have
been effected in the Pliocene period, although in America several
species, and more particularly the commonest form, M. Ohioticus
or M. giganteus, survived into the late Post-Pliocene.

Remains of true elephants have been found in China and Japan,t
and it appears not unlikely, from a fragment of tusk recently de-
scribed by Professor Owen as Notelephas, that a proboscidean,

* The Loup Fork beds, in which several of the American species occur,
are by Professor Cope considered to be of Upper Miocene age. This author-
ity recognises nine species of North American mastodon, to which a tenth
one, M. Floridanus, has recently been added by Dr. Leidy.

+ At least two of the Indian forms—E. Cliftii and E. insignis—referred to
the group Stegodon, which in dental characters stands intermediate between
the mastodons and true elephants, have been identified by Koken as occurring

in the Pliocene deposits of China, and by Naumann in the nearly equivalent
series of Japan.

MASTODONS. 367

whether elephant or mastodon, also existed in Australia. The
mastodon is also known from South America (M. Andium, M. Hum-
boldtii).

Of the recognised true proboscideans the genus Dinotherium
may be considered to represent the earliest type, inasmuch as its
remains are thus far known only from the Miocene and Mio-Plio-
cene deposits (Europe and Asia).

Extinct Animals related to the Proboscidea. — Numerous
extinct animal forms, of both small and gigantic dimensions, ex-
hibiting more or less intimate relationship with the Proboscidea,
have been described from the Eocene deposits of both Europe and
America. Amorg the best known of these is the genus Coryphodon
(order Amblypoda of Cope), with about fourteen species, vegetable
feeders, ranging in size from the dimensions of a tapir to that of an
ox, and, judging from the skeleton, most nearly resembling among
living animals the bear in outward appearance. The structure of
the foot was largely that of the elephant. All the species are
Lower Eocene (England, France, America). Belonging to the same
order are the American Dinocerata, animals equalling or surpassing
in size the modern elephants, to which they bore many points of
structural resemblance. The upper jaw was provided with a pair
of vertically descending canine tusks. The type genus of this
group is Uintatherium, and seemingly the other forms which have
been described under Loxolophodon, Eobasileus, Dinoceras, and
Tinoceras also belong here. Some twenty-nine species are known,
all of them of the Middle Eocene period.—A form uniting the
coryphodons with the Dinocerata has recently been discovered by
Professor Scott in the Bridger (Middle Eocene) beds of Wyoming, ,
and named Elachoceras parvum.”*°

The members of the amblypod order of Mammalia, as well as
the more recent Proboscidea and Hyracoidea (conies), are traced
back by Professor Cope to a type of ungulate animals which largely
preceded these in the order of ‘their development, and which are
by that naturalist considered to represent the primitive hoofed
forms whence the modern even- and odd-toed ungulates, the Artio-
dactyla (deer, ox, camel, &c.) and Perissodactyla (horse, rhinoceros,
tapir), ultimately descended. The teeth were tuberculated (of the
bunodont or hog type), and the feet largely plantigrade, provided
with five toes, both front and rear, constituting the generalised

868 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

mammalian foot. The best-known genus of the order (Condy-
larthra), which comprised animals intermediate in size between the
opossum and tapir, is Phenacodus, from the Puerco and Wasatch
Eocene.

Ungulata Perissodactyla (Odd-toed hoofed-animals).—The
only modern representatives of the odd-toed ungulates are the
rhinoceros, horse (including the zebra and ass), and tapir. Of the
first some five or six species are known, which are generally re-
ferred to a single genus Rhinoceros, although by some authors
several distinct genera are recognised. The African species (R.
bicornis, R. keitloa(?), and R. simus, the so-called white rhinoceros),
all two-horned, occupy the greater part of the continent south of
the desert, while in Asia the species, both single- and double-
horned, range from the forest-covered foot-hills of the Himalayas
through Farther India and the Malay Peninsula to Borneo, Java,
and Sumatra. The common Indian species, R. unicornis or In-
dicus, is now restricted in its range almost wholly to the terai re-
gion of Nepaul and Bhotan, and to the upper valley of the Brah-
maputra. Many species of rhinoceros, in part referable to the
genus or genera which contain the modern forms, are found fossil
in Europe and India in deposits dating from the Upper Miocene;
Rhinoceros (Ceratorhinus) Schleiermacheri is Middle Miocene. The
hornless genus Aceratherium, which, on the American continent, is
preceded in the Upper Eocene by the somewhat rhinocerotic Amyn-
odon, and which may be considered as the first true rhinoceros, ap-
pears in the Lower Miocene deposits of both the Old and the New
World, and is looked upon by many as the ancestral type whence,
through migration and subsequent development, the existing and
Post-Pliocene (R. tichorhinus, &c.) species have been derived. The
American genus Aphelops, likewise hornless, belongs to a series of
deposits (Loup Fork) which by some authors are referred to the
Upper Miocene, and by others to the Lower Pliocene. Hyracodon,
a genus in many respects allied to the rhinoceros, but possessing
only three toes to the foot, is Lower Miocene or Oligocene (North
American). Singularly enough, no rhinocerotic form is found in
the New World above the Pliocene.—None of the existing species
of rhinoceros antedate the Post-Pliocene period, although the
African bicorn type is actually represented in the earlier deposits
of Greece (R. pachygnathus) and the Siwalik Hills of India, which

TAPIRS. 369

last also contain the remains of several forms closely allied to the
existing Indian species (R. Sivalensis, R. paleeindicus).

Of the tapirs (Tapiride) there are at present five or six recog-
nised species, one of which, the Malay tapir (Tapirus Malayanus),
inhabits the Malay Peninsula and the islands of Borneo and Suma-
tra, and the remainder the forest regions of South and Central
America, one or more of the species ascending the Andean slopes to
heights of from 10,000 to 12,000 feet. The Central American forms
(T. Bairdi, T. Dowi) have been referred by Gill to a distinct genus,

-Elasmognathus. The genus Tapirus itself, which is not known in
North America previous to the Post-Pliocene period, extends back
in Europe to the Upper or Middle Miocene, and has continued with
but slight modification of form from that time up to the present
day. Its precursor appears to have been the Listriodon (Middle
Miocene), which united it with the somewhat tapiroid group of
the lophiodons (Lophiodontide—Eocene), the earliest group of
known perissodactyls, comprising animals ranging in size from the
rabbit to the ox. It is difficult, or impossible, to determine just
whether the tapirs constitute a primarily Old World or New World
group of animals, for, despite the intimate relationship which is
established between them and the European Lophiodon through
Listriodon, an equally close connection unites them on the western
side of the Atlantic with genera—Helaletes (Tapirulus?), Desmato-
therium, and Hyrachyus—which appear to have been contempora-
neous with Lophiodon, and, indeed, may have preceded it. Nor
is it exactly impossible, as Professor Vogt has suggested, that a
parallel development on opposite sides of the Atlantic may have
evolved similar forms from slightly different ancestors. The scanty
remains of tapirs in the American Miocene formation are referred
by Professor Marsh to the genus Tapiravus ; between these and
those of Post-Pliocene age there intervenes a complete hi-
atus.

Of the horses (Equide) there are usually recognised three groups:
the horses proper, the asses, and the zebras. By most zoologists
these are all placed in the one genus Equus, the characters defining
Asinus (the asses) not being considered to be of generic value.
Until Poliakof quite recently made known the existence of a
new species of horse (E. Przevalskii) from the desert wilds of Cen-
tral Asia it was generally supposed that the domestic animal (E.

370 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

caballus) was the only living representative of the caballine section
of the family, and that no truly wild stock any longer existed on
the surface of the earth. Whether Przevalski’s horse proves to
be a good species or not, there can be little or no question as to
the normally wild state in which it occurs. The domestic animal
has been spread through the agency of man over the greater part
of the globe, where in nearly all localities it has flourished to a
remarkable degree. That America was wholly, or in great part,
deficient in horses at the time of the Spanish conquest, is proved
beyond doubt, but at the same time it is equally proved, from the
number of fossil remains that have been found between Escholz
Bay in the north and Patagonia in the south, that the animal not
only inhabited, but abounded on, the continent during a period com-
paratively recent preceding. There is, further, very little question
as to the contemporaneity of the horse and man on the American
continent, and, indeed, it would appear not exactly improbable,
from certain references contained in old narratives, that at least in
South America the animal still lingered on even after the advent of
the Europeans. What led to its general extermination, when under
apparently similar physical conditions the introduced animal has
been able to thrive to such a wonderful degree, is a problem which
still awaits solution.

The species of ass appear to be more numerous than those of
the horse, although not unlikely one or more of the forms usually
considered distinct will have to be classed as mere varietal types.
Zoologists are practically agreed that the domestic animal (E. asi-
nus) is either identical with, or only a feebly modified derivative
from, the wild ass of Abyssinia (E. teniopus), the only African
species, which it very closely resembles. Three generally recog-
nised species of ass roam over the wilds of West-Central Asia, the
Syrian ass (E. hemippus), the onager (E. onager), from Persia and
Northwest India, and the kiang or dziggetai (E. hemionus), the
most horse-like in appearance, which inhabits the high table-lands
of Thibet, at elevations of 15,000 feet and upwards. Two species
of zebra—the quagga (E. quagga) and dauw or Burchell’s zebra
(E. Burchellii)—inhabit the plains of South Africa, while a third
species, the mountain zebra (E. zebra), frequents the mountainous
districts of the same region. A fourth form (E. Grévyi) has re-
cently been described by Milne-Edwards from the land of Shoa,

HORSES. Bye!

and is probably identical with the form seen by Speke and Grant
during their journey to the lake regions.

Ot the fossil forms of Equus there have been thus far described
some twenty or more species, which date back in both hemi-
spheres to the Pliocene period. Only two of the recent species are
positively known in the fossil state—the E. asinus, or ass, which is
Post-Pliocene, and the horse (E. caballus), which appears to be
first known from the Upper Pliocene ; it is not improbable, how-
ever, that some of the Post-Pliocene equine remains of Central
Europe belong to the dziggetai. The Pliocene species seemingly
most nearly related to the modern horse are the E. major or E.
Americanus, from the deposits of North America, and the E. Ste-
nonis, from the Val d’Arno, Italy. The only other genus of
Equide besides Equus is Hippidium (Pliohippus ?), which occurs
fossil ia the Pliocene deposits of both North and South America.

Nehring, from a careful study of the numerous fossil remains of
horses found in Germany and elsewhere, arrives at the conclusion
that the present European animal—at least, as representing some
of the races—instead of being, as is commonly supposed, a recent
introduction from Asia, is in reality indigenous to the region which
it now inhabits in a domesticated state, and that it has been a con-
tinuous inhabitant of Central Europe, then largely in the form of
a steppe country, supporting a steppe fauna, ever since the early
part of the Quaternary epoch.

Extinct Animals related to the Horse and Tapir.—In no
group of mammals, probably, is the difficulty of drawing family
boundaries greater than among the perissodactyl ungulates, a cir-
cumstance due chiefly to the perfection with which many of the
lines of descent have been traced out, and to the intimate rela-
tionship which the animals of one line bear to the animals of one
or more other lines. Thus the primitive ancestors of the horse—
the four-toed and three-toed (fore and aft) Eohippus and Orohippus
(Hyracotherium) from the Eocene, the three-toed Mesohippus and
Miohippus (Anchitherium) from the Miocene, and the Pliocene
Hipparion (also Miocene) and Protohippus—which form an almost
continuous chain connecting Eohippus and the Equidi, belong to
two or three families, Lophiodontide, Palzotheride,* Anchithe-

* To the type genus of this family, the Eocene Paleotherium, many paleon-
tologists have traced the ancestral line of the European horse—Equus Stenonis,

372 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

ridx, one of which, at least, lies as much in the direct line of descent
of the tapir as it does of the horse. It will thus be seen that from
the evolutionary standpoint, or from the point which views rela-
tionship by descent as of equal importance with that which unites
forms solely through a community of general characters, family
lines could be traced among these earlier ungulates at points other
than where they have actually been drawn, and with fully as much
reason. For it can scarcely be gainsaid that the direct ancestors
of the horse, for example, would form as natural a group among
themselves as they now form three or four groups in the way they
have been scattered about.

Other tapiroid forms, more or less closely related to the lophio-
dons, are Limnohyus and Palosyops, both from the Eocene ;
Chalicotherium, whose remains have been found in Oregon, and in
Eurasia from France to China, appears in the Oligocene and Mio-
cene. Approximately contemporaneous with the last, and embrac-
ing animals of the dimensions of the elephant, or even larger,
with certain resemblances to the rhinoceros, were the Menodon-
tid, whose remains have been found in both hemispheres. Sev-
eral genera of this family—Menodus, Titanotherium, Symborodon,
Brontotherium—have been described, but it would appear that not
all of these are entitled to generic recognition.

A group of highly specialised and abnormal forms of Perisso-
dactyla, concerning which there has been much diversity of opinion
expressed, and whose position in the zoological scale has not yet
been definitely established, is that of the Macrauchenide, with the

Hipparion, Anchitherium, Paleotherium.—Dr. Max Schlosser, in an elaborate
review of the phylogenetic relationships of the Ungulata (‘* Morphologisches
Jahrbuch,”’ 1886), considers the equine line of descent to pass through Phena-
codus (as earliest form), Hyracotherium, Anchitherium, Merychippus, Hippa-
rion, and Pliohippus. Hyracotherium and Hipparion, and possibly also An-
chitherium, are assumed to be by origination American forms, which subse-
quently wandered over to Europe, but the relative appearance of these forms
on the two continents scarcely warrants this supposition. The same author-
ity identifies the American Mesohippus and Miohippus with Anchitherium,
and Protohippus with Hipparion; Eohippus is considered to be probably
identical with Hyracotherium. By Mr. Wortman, on the other hand, who
first recognised jn Phenacodus the earliest ancestor of the horse, and who
unequivocally identifies Orohippus with Iyracotherium, both Mesohippus and
Protohippus are considered to represent types of distinct generic value (‘‘ Revue
Scientifique,’’? June, 1883).

HIPPOPOTAMI, 373

two species Macrauchenia Patachonica and M. Boliviensis, remnants
of the remarkable South American Pliocene fauna. With certain
characters approximating it to the camel and horse, it is claimed
by Burmeister that the animal was provided with a proboscidiform
trunk.

Ungulata Artiodactyla (Even-toed hoofed-animals). — The
members of this sub-order, both recent and fossil, are conveniently
divided into two groups—those which, like the hog, have the
grinding surfaces of the molar teeth tuberculated (Bunodonta),
and those, in which these surfaces are crescentically ridged, as in
the sheep, ox, deer (Selenodonta). The first of these groups, the
Bunodonta, comprises but two families, the swine (Suidee) and
the hippopotami (Hippopotamide).

Of the hippopotami there are, as generally recognised, only
two species, the common form (H. amphibius), which until re-
cently inhabited most of the larger streams of the continent of
Africa, from the Congo, Senegal, and Zambesi to the Nile, but
whose domain has of late been rapidly narrowing (completely ex-
cluded from the Egyptian Nile), and the West African Cheeropsis
Liberiensis, a comparatively small animal, differing primarily from
the first in the possession of only a single pair of incisors in the lower
jaw instead of two pairs. A third species, whose remains have
been found sub-fossil in the swamp deposits of the island of Mada-
gascar (in association with the giant Apyornis), and which may
consequently be classed with the recent period, has been described
by Goldberg (1883) under the name of H. Madagascariensis. The
common species of hippopotamus represents one of the most an-
cient of the mammalian types entering into the formation of the
modern fauna, it being one of the very few forms which survived
the Pliocene period up to the present day. Its range was formerly
very much greater than it now is, and even as late as the Post-Plio-
cene it appears to have inhabited Europe as far north as Northern
Wales, where its remains have been found associated with human
implements. Seven other species of the genus have been de-
scribed from the Pliocene and Post-Pliocene deposits of Europe
and India, but none have so far been recorded from America.—The
pigmy hippopotamus of Malta (H. minutus) appears to have been
closely allied to, if not identical with, the living Liberian spe-
cies.

3874 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

The recent hogs are commonly divided into three more or less
distinct groups: the peccaries (genus Dicotyles), whose range
comprises the region included between Arkansas and Paraguay ;
the wart-hogs (khacocherus) of East and South-Central Africa;
and the true swine, under which are ranged the hog proper (Sus),
the babyrousa (Babirusa), and river-hog (Potamocherus). The
last is exclusively West African, while the babyrousa is confined
to Celebes, and some of the smaller islands of the Eastern Archipel-
ago (Bouro, &c.). Much diversity of opinion still exists as to the
number of species that are comprised in the genus Sus. Some
fifteen or more have at various times been recognised by zoolo-
gists, but by Forsyth Major,’ who has probably enjoyed better
opportunities for making a critical study of the group than any of
his predecessors, the number is restricted to four, with a probable
fifth one, concerning which we know little, but which appears to
occupy a considerable part of the Ethiopian region: Sus vittatus,
whose distributional area extends from Sardinia to New Guinea,
and from Japan to Damara-Land (Southwest Africa); 5. verrucosus,
from Java and Ceiebes; 8. barbatus, from Borneo; and §. scrofa,
the boar, or common hog, whose domain extends, or did extend
before man had greatly narrowed its limits, over the greater part
of temperate Europe and Asia. This species, which was an early
inhabitant of Britain, as is indicated by the remains found in
the forest-bed (Post-Pliocene) of Norfolk, was completely exter-
minated in that region a number of centuries ago. Several
species of the genus have been found fossil in the Miocene and
Pliocene deposits of France, Italy, Germany, and Greece, and five
are described from the Siwalik Hills of India, one of which, 8.
Titan, is considered by Lydekker to have attained in extreme
specimens a height to the shoulder of forty-nine inches or more.
None of the genera of recent bunodont Artiodactyla are found
fossil in America with the exception of Dicotyles (peccary), which,
in association with a nearly related genus, Platygonus (also Plio-
cene), occurs in the Post-Pliocene deposits. Closely related to the
last are the Miocene Thinohyus, Cheenohyus, and Hyotherium
(Palzocheerus ?), the last a genus also abundantly represented in
Eurcpe in deposits of both Upper Eocene and Miocene age. The
oldest representatives of the suilline tribe appear to be the forms
that have been described as Eohyus and Achzenodon (Parahyus 2),

CAMELS. 375

of Lower and Middle Eocene age, the former of which is stated by
Marsh to have had at least four functional toes, while the latter
united with its predominant suilline characters certain peculiar car-
nivore modifications of the skull. Some very remarkable buno-
donts of a hog-like character, found in the phosphorite deposits of
Quercy, France, and named by Filhol the Pachysimia, are consid-
ered by that author to possess some striking structural features
allying them with the Primates, and rendering it not exactly im-
probable that the last may find their earliest ancestors in these
ancient types.

Of somewhat doubtful position, but with distinctively suilline
affinities, are Choeropotamus (Eocene) and Anthracotherium and
Hyopotamus (Eocene—Miocene).

Artiodactyla Selenodonta.—Among recent forms this section com-
prises the camels (Tylopoda), chevrotains (Tragulina), and true
ruminants (Ruminantia), with such well-known forms as the ox,
goat, deer, and antelope.

The camels, constituting the family Camelide, comprise, as gen-
erally recognised, two genera—the Old World Camelus, the camel
proper, and the New World Auchenia, the llamas (guanaco, vicuia,
alpaca). Of the former there are two species, the dromedary, or
one-humped animal (C. dromedarius), a native of the deserts of
Arabia, whence it has spread eastward to India, and the Bactrian,
or two-humped camel (C. Bactrianus), which occupies the region of
Central Asia from the Black Sea to China, and from the Himalayas
to beyond the Siberian boundaries. Although the camel is gener-
ally considered to be a belonging of the hotter regions of the earth’s
surface, it is well known that the Bactrian species thrives admira-
bly in the northern districts of Mongolia, and that even as far
north as the southern extremity of Lake Baikal, on the fifty-third
paraliel of latitude, it passes the rigours of a Siberian winter with-
out apparent discomfort. That the dromedary, which is now one
of the distinctive animals of North Africa, was unknown to the
ancient Egyptians is proved by the absence of representations of it
from all monumental inscriptions. The American representatives
. of the Camelide are the llama, alpaca, guanaco, and vicufia, con-
stituting the genus Auchenia, the first two of which, inhabitants
of the Peruvian and Bolivian Andes, exist now only in a state of
domestication, while the vicufia inhabits the Andean slopes of Peru

376 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

and Chili, and the guanaco the plains of Patagonia and Tierra del
Fuego.

The Tertiary deposits of Europe have thus far yielded no traces
of the Camelide, and if we except the Camelus Sivalensis and
C. antiquus, from the Siwalik Hills of India, and C. Thomasi, from
the Quaternary deposits of Algeria, the same may be said of the
Eastern Hemisphere generally. On the other hand, animals refer-
able in part to this family, and, again, others closely related to these,
are abundant in America, where they form a connecting series or
chain almost as complete as that which has been established for the
horse. The cameline line of descent has been traced by Professor
Cope from the Oligocene or Miocene Poebrotherium, in which, as
well as in the succeeding genus, the metapodial bones were dis-
tinct, and the mouth was furnished with a complete series of in-
cisor teeth, through Protolabis, Procamelus, and Pliauchenia (Plio-
cene), the last standing in the relation of its dentition intermedi-
ately between Procamelus and the camel. Auchenia, the llama,
which may be considered to terminate the series, is late Pliocene
and Post-Pliocene ; with it occur associated several related forms,
as Protauchenia, Paleolama, &c. Professor Marsh indicates the
Eocene Parameryx as the probable most ancient ancestor of the
camels, whereas by Scott, Osborn, and Speir this place is given toa
contemporaneous genus Ithygrammodon.

It would appear, therefore, that the camels are a New World
family, but this is by no means proved to be the case ; the absence
of the true cemel in America and its occurrence in India in deposits
as ancient as the older Pliocene, render it very probable that an-
cestral cameline forms will be found in the Old World as well as
in the New. :

The chevrotains, or mouse-deer (Tragulidx), which comprise
some of the smallest of known ungulates, and which in structure
stand in a measure intermediate between the deer and hog, are
ranged under two genera, Tragulus and Hyzmoschus, the former
restricted to Southern and Southeast Asia, and the larger islands of
the Eastern Archipelago, and the latter to West Africa. The family
dates from the Miocene period, of which the genus Hyemoschus is
a belonging.

Of the true ruminants, the Camelopardalide, or giraffes, con-
stitute perhaps the most peculiar group. Only one species, Camelo-

ANTELOPES. 377

pardalis giraffa, is known, which ranges over the greater part of
the grass-covered plains of East-Central and South Africa. An
extinct species of the genus, C. Attica, which occurs in the Mio-
cene deposits of Greece, appears to have rivalled or fully equalled
the modern form in size. Other allied species have been described
from the Siwalik Hills of India. The Helladotherium, an animal
of less elevated proportions than the giraffe, but closely related to
it, roamed during the Miocene, or early Pliocene, epoch over the
south of Europe, from France to Greece, and across to India. With
the same family are possibly to be placed also the Siwalik genera
Brahmatherium, Vishnutherium, and Sivatherium, the last a huge
antelopine form, referred by most zoologists to the true antelopes.

The antelopes, whose special distribution has been considered
in connection with the several zoogeographical regions of the earth’s
surface, constitute by far the most extensive group of the Ungulata,
there being probably not less than one hundred distinct species.
The greater number of these belong to the continent of Africa,
where they inhabit as well the desert tracts as the open plains and
forests, from the Sahara to the Cape, and from Senegal to the Nile.
Among the better known of these forms are the springbok, blesbok,
bontebok, hartebeest, buschbok, waterbok, koodoo, oryx, gemsbok,
klipspringer, gnu, and eland, the last a bubaline form equalling in
size a large ox. The opposite extreme in the series is presented by
the western guevi, which barely exceeds the dimensions of a rabbit.
The fifteen (?) or more Asiatic species, whose combined range com-
prises very nearly the entire extent of the continent, with the islands
of Japan, Formosa, and Sumatra, are nearly all distinct from the
African, and even the generic types that are held in common are
limited almost exclusively to such forms, as Oryx, Addax, and
Gazella, whose domain embraces the almost contiguous desert tracts
of Northeast Africa and Arabia.

Europe has but two antelopine species, the Alpine chamois and
the saiga, or steppe antelope, the latter of which may perhaps with
more propriety be considered an Asiatic species, whose range ex-
tends over Russia to the confines of Poland. North America is
equally deficient with Europe, holding likewise but two species—
the prong-horn (Antilocapra) and Rocky Mountain goat (Aplocerus)
—while in South America the family or group is entirely wanting.

The remains of antelopes, if we except certain doubtful forms

3878 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

from the cave deposits of Brazil, which have been referred to Anti-
lope and Leptotherium, are completely absent from America. In
Southern and Western Europe they date from the Miocene period,
continuing through the Pliocene and Post-Pliocene. The richest
antelopine deposit is that of Pikermi, Greece, whence Professor
Gaudry has described the genera Gazella, Palzotragus, Tragoceros,
Paleoryx, and Palzoreas, the last two most intimately related
to the recent Oryx (gemsbok) and Oreas (koodoo) respectively.
Several, or most, of these types have also been recognised 1n the
more or less equivalent deposits of France, Spain, Italy, and the
Vienna Basin ; Antilope cristata of the Middle Miocene of Switzer-
land appears to have had its nearest ally among recent forms in
the chamois. African-type antelopes are still met with in the
late Pliocene, or Post-Pliocene, volcanic deposits of the Auvergne
(France). The only unequivocal antelopine remains from Britain
are those of Gazclla Anglica, recently described by Mr. Newton
from the newer Pliocene beds of Norwich, England ; not impossi-
bly, however, the saiga is also represented in the English fauna.
Some eight or more species of the family, principally referable to
modern genera—Oreas, Paleoryx, Portax (nylghau), Gazella, An-
tilope, and Alcelaphus—have been described from the early Plio-
cene of the Siwalik Hills.

The bubaline or bovine ruminants proper (Bovina) comprise
about thirteen recent species, which are distributed over the greater
part of Eurasia, Africa, and North America. The buffaloes are
represented by four species, two African, Bubalus Caffer (Cape
buffalo) and B. brachyceros, tlhe former of which roams over the
greater part of Southern and Central Africa, and two Asiatic, the
Buffelus Sondaicus and B. Indicus, from the last of which has
descended the domesticated variety which has been so extensive-
ly acclimatised in North Africa, Italy, Greece, and Hungary. A
form related to the buffaloes, but differing in certain important
essentials, is the dwarf wild-cow of the island of Celebes (Anoa or
Probubalus Celebensis), whose early representatives occur fossil in
the Pliocene deposits of the Siwalik Hills of India. Two species
of buffalo, referable to the genus Buffelus, likewise occur fossil in
the Indian deposits (Pliocene and Post-Pliocene), and one species,
B. Pallasii, in the Quaternary of Danzig, Germany. Associated with
the former are the bubaline forms Amphibos (Hemibos) and Lepto-

CATTLE, SHEEP, GOATS. 379

bos. The African buffalo is thus far known only from the Qua-
ternary of that continent (Bubalus antiquus, from Setif, Algeria).

The wild cattle (ghaurs) of India, including, according to some
authorities, the Thibetan yak * (Poephaga grunniens), and constitut-
ing the genus Bibos, range from Southern India through the Malay
Peninsula to Java and Borneo. The earliest representative of this
group appears to be the Etruscan bull (Bos or Bibos Etruscus),
from the Pliocene deposits of France and Italy.

The bisons (genus Bison) are at present comprised in two spe-
cies, the American (B. Americanus), which until recently inhabited
the greater part of the continent of North America, but which is
now restricted to a few hundred individuals, and the European
(B. Europzus), also known as the aurochs, which up to the pe-
riod of the Roman Empire appears to have been sufficiently abun-
dant in South-Central Europe, but which is now limited to the
imperial preserves of Lithuania and the wilds of the Ural and Cau-
casus. Its immediate precursor was the Bison priscus, whose
remains are distributed throughout the Quaternary deposits of al-
most every country in Europe and of Siberia; they have also been
found at Escholtz Bay, Alaska. The Pliocene B. Sivalensis would
seem to be a closely allied form, and, according to Ritimeyer,
nearer to it than to the living American species, or to its Post-
Pliocene predecessors, the B. latifrons and B. antiquus.

Of the taurine genus Bos, which comprises the domestic cattle,
several well-marked varieties are recognised, all of which are by
most authorities referred back in their descent to the urus (Bos
primigenius), which was abundant in Central Europe in the time
of the early Roman emperors, but is now wholly extinct. By
Wilckens, on the other hand, it is claimed that at least some of the
breeds of cattle are the descendants of the European bison.

The sheep and goats constitute an almost exclusively Old World
group of hollow-horned ruminants, of which there are but two in-
digenous representatives in the Western Hemisphere (North Amer-
ica). One of these is the Rocky Mountain sheep (Ovis montana),
which is very closely related to the argali of East-Central Asia,
and the musk-ox (Ovibos moschatus), which inhabits the region of
Arctic America north of the sixtieth parallel of latitude, or there-
abouts, but whose fossil remains are met with as well in the

* Przevalski describes a second species of yak as P. mutus.

380 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Quaternary deposits of Eurasia—England, France, Germany, Si-
beria, &c.—as in America. The range of this species, or of forms
closely allied to it (O. bombifrons, O. cavifrons), on the American
continent at one time extended to the confines of Arkansas.

The Old World Caprina, whose special distribution has already
been discussed in the zoogeographical part of this work, comprises
some twenty or more species, which, with two exceptions—a Neil-
gherry goat and an Abyssinian ibex—are confined to the Holarctic
region, or to this and the Mediterranean transition tract. It is a
somewhat surprising circumstance, in view of the broad distribu-
tion of the goats, that the sheep, which have obtained such a
firm foothold in the mountainous and intermountainous regions
of Asia, should be almost entirely wanting from the continent of
Europe—indeed, from the entire Eurafrican region, if we except
the islands of Corsica, Sardinia, and Crete, the Balkan Peninsula,
and some isolated spots on the Atlas Mountains. No unequivocal
remains of the goat or sheep, except Ovibos, have thus far been
discovered in any American formation, and in Europe such remains
are confined almost exclusively to the Quaternary cave and brec-
cia deposits (France, Italy). In India, however, they have been
traced back to an older period; Capra Sivalensis, a form closely re-
lated to the recent Iharal of the Neilgherries, has been described
from the Pliocene of the Siwalik Hills, and Capra Perimensis,
whose remains would seem to have been associated with those of
Dinotherium and Aceratherium, animals indicative of the Miocene
period, from the island of Perim. A remarkable hornless form, to
which Riitimeyer has given the name of Bucapra Daviesii, also
belongs to the Siwalik fauna.

The most important group of ungulates after the antelopes is
constituted by the deer (Cervidz), which comprises some sixty
or more species—excluding the Central Asiatic musk (Moschus)
and the giraffe which are referred here by some authors (Riti-
meyer)—distributed over the greater portion of both the Old and
the New World. Australia, as in nearly all other mammalian
groups, is entirely deficient, and Africa counts but two species,
the fallow-deer and a stag, which inhabit the Mediterrangan re-
gion. The South American forms, whose domain extends com-
pletely across the continent to Tierra del Fuego, have been placed
in the genera (or sub-genera) Pudu, Coassus, Furcifer, Blastocerus,

DEER. 3881

and Cariacus, the last of which comprises all the North American
deer north of the Mexican boundary, with the exception of the
Canada stag or wapiti (Cervus Canadensis), the moose (Alces mach-
lis) and reindeer (Rangifer tarandus), the last two of which are cir-
cumpolar, and inhabit the whole northern portion of the Eurasiatic
continent, from Norway to China. The European forms are com-
prised under the three groups Cervus, which includes the stag or
red-deer (C. elaphus), whose range embraces, or until recently em-
braced, the whole of Europe and a large part of Northern Asia;
Dama, the fallow-deer, a native of the Mediterranean districts of
Europe, Asia, and Africa; and Capreolus, the roe, which was at
on2 time extensively distributed over nearly the whole of Europe,
with the exception of the greater part of Russia. Among the bet-
ter-known Asiatic forms are Axis (peninsula of India, Ceylon, China)
and Rusa, the latter containing some of the largest of the cervine
tribe, several species of which inhabit the hotter regions of Hither
and Farther India, and the islands of the Eastern Archipelago. The
muntjacs (Cervulus), which seem to connect the true deer with the
musks, inhabit the forest tracts of the Oriental region, from India
to China, and from Formosa to the Philippines, Java, and Bor-
neo.

The earliest cervine animals, in the strict sense of the term, with
which we are acquainted, are met with in the Middle Miocene de-
posits of France and Germany, where forms showing evident rela-
tionship with the muntjacs, and possessing the simplest kind of horn
structure—a simple bifurcated stem—have been variously described
as Procervulus, Prox, Dicrocerus, Palwomeryx, and Micromeryx.
These are all united by Ratimeyer into the one genus Paleomeryx,
to which is also added the supposed differing Dremotherium from
the same, and a possibly lower (Lower Miocene), horizon. Of equiv-
alent age is the hornless Amphitragulus. The progressive devel-
opment from the simple-formed antler to the more complex has
been traced through numerous forms of Cervus from the Upper
Miocene to the Post-Pliocene, the most complex structure known
being that exhibited by C. dicranios, from the Pliocene of the Val
d’Arno, Tuscany.. Professor Boyd Dawkins thus sums up his ob-
servations on this point : ‘‘We may gather from the study of the
fossil Cervide the important fact that in the Middle Miocene age
the cervine antler consisted of a simple forked crown only. In

382 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

the Upper Miocene it becomes more complex, but is still small and
erect, like that of the roe. In the Pliocene it becomes larger and
longer, and altogether more complex and differentiated, some forms,
such as the Cervus dicranios of Nesti, being the most complicated
antlers known either in the living or fossil state. These succes-
sive changes are analogous to those which are to be observed in
the development of the antlers in the living deer, which begin
with a simple point and increase their number of tines until their
limit is reached. It is obvious, from the progressive diminution
in size and complexity of the antlers in tracing them back from
the Pliocenes into the Upper and Middle Miocenes of Europe, that
in the latter period we are approaching the zero of antler devel-
opment. In the Lower Miocenes I have failed to meet with evi-
dence that the deer possessed any antlers.” *°°

The roe, stag, elk, and reindeer occur fossil in the Quaternary
deposits, together with a giant form, the Irish stag (Cervus me-
gaceros), whose extinction appears to have been effected long after
the region inhabited by it was also inhabited by man. The stag
(wapiti), elk, and reindeer also occur fossil in the American Post-
Pliocene deposits, the last, as in Europe, in latitudes very much
lower than it now occupies. The genus Cervus dates from the
Pliocene. A Quaternary form intermediate in many points of
structure between the true deer and the elk, and originally re-
ferred to the latter, has recently been re-described by Scott as Cer-
valces (C. Americanus). Its remains have thus far been met with
only in New Jersey and Kentucky. The hornless Miocene genus
Leptomeryx, which by Leidy and Marsh is placed near the Cervida,
is by Rutimeyer considered to more nearly approach the camels.

Of undeterminable position among the Ruminantia, but more or
less closely related to each other, and showing certain analogies of
structure with the Tragulina, are the Old World Lower and Middle

ertiary genera, Anoplotherium, Xiphodon, Dichobune, and Caino-
therium. An equally aberrant type of American ruminants, the
“ruminating hogs” (Oreodontid) of Dr. Leidy, whose remains are
exceedingly abundant in the Western Territories, appears to have
been nearly related to the Anoplotheride. Thirty-five species,
with three exceptions (Merychyus—Pliocene), all belonging to the
Miocene period, are referred to this family by Professor Cope.™

CATS. 883

One of the genera of the family, Agriochcerus, seems to be also
represented in the deposits of the Siwalik Hills.

Carnivora.—The members of this order may be conveniently
classed under four primary groups, defined in their broadest sense
as the cats (4Zluroidea), dogs (Cynoidea), bears (Arctoidea), and
seals (Pinnipedia). The first of these embrace the cats proper (Fe-
lid), civets (Viverride), the South African aard-wolf (Proteles
Lalandii), and the hyenas (Hyznide).

The true cats, which by many authorities are considered to be
comprised within the single genus Felis, have an almost world-wide
distribution, but are most abundantly developed in regions of
elevated temperature. - No species occurs in either the Australian
region or Madagascar. The better-known American forms are the
jaguar (F. onca), whose range comprises the entire region included
between Patagonia and Texas; the cougar or puma (F. concolor),
with probably the most extended north and south range of any
mammalian species—Patagonia to the sixtieth parallel of north
latitude ; the ocelot (F. pardalis), which, in one or other of its
several varieties, ranges from Arkansas through Texas and Mexico
to Patagonia; the nearly equally distributed margay (F. tigrina—
Mexico to Paraguay), and several allied species of small intertropical
“‘ tiger-cats;”’ the jaguarundi (F. yaguarundi) and eyra (F. Eyra),
unspotted cats ranging from Paraguay to the northern boundary of
Mexico, the Chilian colocollo (F. colocollo), the pampas-cat (F.
pajeros), and the lynx. The last, of which several species or varie-
ties have been described, in whole or in part identical with the
common European species (F. lyncus or rufa), inhabits the greater
part of the American continent north of Mexico.

Of the Old World cats, besides the lion and tiger, whose range
has been specially considered in the zoogeographical portion of this
work, the better-known forms are the Felis pardus, leopard or pan-
ther, which may represent several distinct species, inhabiting the
greater part of Africa and the warmer regions of Asia, from Pales-
tine to Japan; the ounce or irbis (F. uncia), of about the size of,
and somewhat resembling, the leopard, a native of the elevated
mountain-tracts of Central Asia (Thibet—Siberia), where it ascends
to heights of from 15,000 to 18,000 feet; the spotted or clouded
tiger (F. macroscelis), an arboreal species, indigenous to the forest
regions of Southeast Asia and the adjoining islands of Formosa,

384 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

Sumatra, Java, and Borneo; the serval (F. serval), from the greater
part of the African continent; and the cheetah or hunting leopard
(F. or Cynzlurus jubatus), whose domain covers nearly the whole
of the African continent and a very considerable part of South-
ern and Western Asia. The lynx or lynxes range from the polar
regions to the Mediterranean, whence they are continued by an
allied form, the caracal, over a large part of both Asia and Africa.
Felis catus, the wild-cat proper, which is met with in both insular
and continenta! Europe, is not, as is frequently supposed, the an-
cestor of the domestic animal; this place is now generally conceded
to the Egyptian and West Asiatic F. maniculata.

Numerous species of the family, referable in considerable part
to the genus Felis of most authors, and differing but little from
forms still living, are found fossil in the Post-Pliocene, Pliocene,
and Miocene deposits of Europe, Asia, and America. Among the
best known of these is the cave-lion (F. speleea), a species but barely
if at all distinguishable from the F. leo, whose remains are abun-
dantly met with in the Post-Pliocene cave deposits of continental
Europe and England. During the same period the existing lion
appears to have hunted its prey as far north as Yorkshire and on
the frontiers of Poland, and the leopard or panther among the
Mendip Hills. Felide, allied to the panther and lynx, have been
discovered in the Pliocene strata of the Siwalik Hills of India.
Felis angustus, from the North American Pliocene deposits, was in-
termediate in size between the jaguar and tiger, while the later F.
atrox, which may be considered to represent in the New World the
European cave-lion, appears to have surpassed in this respect both
the lion and the tiger. In association with the modern type-forms of
Felidz there occur others which depart very widely from these, the
most remarkable of which, as representing the most highly special-
ised forms of the family, and as strictly the most carnassial of all
known Carnivora, were the so-called sabre-tooths. The animals of
this group are characterised by a prodigious development of the,
upper canines, which in some instances appear to have measured as
much as seven or nine inches in length. The best-known genus is
Machairodus (Drepanodon), whose remains have been found in both
the Miocene and Pliocene deposits of Europe (Pliocene of India),
and whose immediate American representative appears in Smilodon
(Pliocene or Post-Pliocene of Buenos Ayres and Texas), a contem-

CIVET-—CATS. 385

porary of the giant sloths and glyptodons. A supposed species of
the last (S. gracilis) has also been described from a cave deposit in
the State of Pennsylvania. Other allied forms are the American
genera Dinictis, Nimravus, Pogonodon, and Hoplophoneus, from
the Lower Miocene deposits of the Western United States, whose
members were intermediate in size between the lynx and tiger.
Eusmilus bidentatus, from the phosphorites of France (Upper
Eocene or Oligocene), although the oldest-known form, is, singu-
larly enough, in many respects also the most specialised. _Contem-
poraries with it were Pseudelurus and lurogale, the former the
representative of the group denominated by Professor Cope the
‘‘ primitive ” non-specialised cats.

The Viverride, or civet-cats, comprise some one hundred or
more species of moderate-sized Carnivora, which are in the main
restricted to the Ethiopian and Oriental regions. The better-known
types are the true civets (Viverra), from North and Tropical Africa,
India, China, and the Malay Peninsula ; the genets (Genetta), from
Africa (the entire continent), Southwest Asia, and Southern Europe
(France, Spain); and the ichneumons or mongooses (Herpestes),
which are widely distributed over the continent of Africa and Indo-
Malaysia. One species of the last is also found in Spain. Among
other genera of the family are Viverricula, the rasses, and Para-
doxurus, palm-civets (both from Indo-Malaysia), Cynogale, the
otter-civets (Borneo), and Cryptoprocta, the last sometimes con-
sidered the type of a distinct family, and the largest of the Mada-
gascan carnivores.

Numerous genera, more or less closely allied to recent forms,
carry this family back to the early Tertiary period, where (in the
phosphorites of Quercy, France) we find two or more species repre-
senting the genus Viverra itself. Others of the same genus (or
possibly Genetta) are found in the French Miocene, and in the
Pliocene of the Siwalik Hills. A remarkable viverrine form, show-
ing intermediate relationships between the civets and the hyenas,
has been described by Professor Gaudry, from the Middle Tertia-
ries of Greece and elsewhere, as Ictitherium.

Three well-differentiated species of hyena are recognised by
zoologists—the striped hyena (H. striata), from Africa generally
and Southern Asia; the spotted hyena (H. crocuta)—Africa, south
of the desert, sometimes placed in a distinct genus, Crocuta; and

386 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

the brown hyena (H. brunnea), from South Africa. Although now
restricted to the continents of Asia and Africa, the numerous re-
mains found in the European Post-Pliocene deposits indicate that
this animal, as well as the lion and other semi-tropical species, was
an abundant form in the north temperate regions at a comparatively
recent period, and that from those parts the Ethiopian realm has
drawn much of its existing distinctive fauna. The widely distrib-
-uted cave-hyena (H. spelea), whose range embraced a part of the
British Isles, was most nearly related to, if not identical with, the
H. crocuta, and was without doubt its direct ancestor. The striped
hyena may be traced back to the older (Pliocene) H. Arvernensis of
Central France, and the brown form not improbably to the Miocene
(or Pliocene) H. eximia of Pikermi, Greece. The aberrant form
Hyeenictis, described by Gaudry from Pikermi, and showing cer-
tain viverrine relationships, is considered by Lydekker to repre-
sent at most only a sub-genus of hyena. No representatives of
this family, either recent or extinct, have thus far been discovered
in America, unless, indeed, the Miocene lurodon prove to be a
distant relative.

The Cynoidea, or canine division of the Carnivora, comprises
but a single family, the dogs (Canidz), whose numerous representa-
tives enjoy a nearly world-wide distribution. Apart from the hunt-
ing or hyena dog of South Africa (Lycaon picta*), the long-eared
fox (Otocyon megalotis), from the same region, and the bush dog
(Icticyon venaticus), from Brazil, all the species—some fifty or more
—may be conveniently grouped in the single genus Canis, whose
range would then be coextensive with that of the family. If the
dingo, or wild-dog of Australia, be proved to be indigenous to that
continent, then the genus will be the most nearly cosmopolitan of
any of the terrestrial Mammalia. Two clearly defined sections of
the genus may be recognised, the lupine and the vulpine, to. the
former of which belong the wolves, jackals, dogs proper, and a
number of not readily classifiable forms which have a general canine
aspect; and to the latter the foxes and fennecs. The origin of the
various breeds or races of the domestic dog is involved in much
uncertainty, and whether their progenitors are to be sought in a

* A fragment of a jaw from the Post-Pliocene deposits of Glamorganshire,
Wales, has been referred to the genus Lycaon by Lydekker (L. Angticus).

DOGS, FOXES. 387

single one of the feral forms now living, as the wolf or jackal, or
in several such forms as are denominated wild-dogs, or in the union
of both, still remains to be determined. The researches of Nehring
seem to indicate that a race of wild-dogs, akin to the existing do-
mestic one, inhabited a considerable part of Central Europe during
prehistoric times. Various forms of wild-dog, as the dhole and
buansuah (sub-genus Cuon), range over the greater part of Asia,
from Siberia to Java and Sumatra, where they in great measure
replace the wolf of the more strictly northern regions. The last
(Canis lupus) is found throughout the whole of Europe and North-
ern Asia, from the Atlantic to the Pacific, dnd also in Nova Zembla
and Japan. There can be little question as to the identity with
this form of the corresponding American species (Canis occiden-
talis), which, in its numerous varieties, covers the entire North
American continent, from Mexico to the Arctic Ocean. The coy-
ote, or American prairie-wolf, is by some authors considered to be
intermediate between the wolf and fox. South America is wholly
deficient in wolves, as in foxes, their place being taken by the fox-
like forms which have been referred to the groups Lycalopex,
Pseudalopex, and Thous. The most broadly distributed of these
is Azara’s dog (C. Azare), which ranges over the greater part of -
Brazil, and southward to Patagonia. The most southerly species
of the family is the Antarctic dog (C. Magellanicus), which inhab-
its Chili, Patagonia, and Tierra del Fuego. Of the remaining
lupine forms the most widely distributed are the jackals, of which
several species are recognised, whose combined ranges embrace the
whole of Africa and much of Southern and Western Asia.

The vulpine section of the Canide includes the fennecs and foxes,
the former all African, the latter—with ten to fifteen species—
spread over the whole of North America and Europe, and largely
also over Asia and Africa, There can be no question (as in the
case of the wolves) that several of the forms that have generally
been recognised as distinct species are in reality only varietal types,
whose inter-relationship is made manifest when full geographical
suites are made use of for comparison. The identity between the
common European fox (C. vulpes) and the American red-fox (C.
fulvus) may be considered as established. Recognised as one
species, the habitat of the common fox of the Northern Hemisphere
may be said to embrace the whole of Europe, North Africa, North

388 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

and Central Asia, and practically the whole of the North American
continent, although it appears to be absent from the immediate
Pacific coast. A well-marked variety of this form, by many natu-
ralists considered to be a distinct species, is the broadly distributed
silver-fox (C. Virginianus), which alone of the different varieties
is represented in Central America. The burrowing-fox (C. velox)
is an inhabitant of the interior region included between the (low-
er) Missouri and Saskatchewan rivers and the Cascade Mountains.
Over a considerable part of North-Central Asia—Tartary, Mon-
golia, Siberia—the common fox 1s replaced by the corsac or steppe-
fox (C. corsac), a closely related species. The most northerly species
of fox is the Arctic fox (C. lagopus), a cireumpolar mainland form,
occurring also in Iceland and Spitzbergen.

The Canidae appear to date from the (Upper) Eocene period,
and not impossibly the genus Canis is itself represented in the form
that has been described by Cuvier as Canis Parisiensis. Less doubt
attaches to the C. Filholi, from the phosphorites of Central France,
whose position, however, still remains somewhat uncertain. Barring
these two forms, the oldest representatives of the family are scen in
the genera Galecynus and Amphicyon, which appear in Europe in
the Upper Eocene and Lower Miocene respectively. In America
Galecynus is unknown prior to the Oligocene (or Lower Miocene—
White River formation), to which period must be referred the most
ancient undoubted remains of the family in the New World. To this
genus, whose representatives appear to have been very abundant
during the Miocene epoch, the existing species of dog are referred
in their line of descent by Filhol and Cope. Canis, which in the
Miocene is associated with a number of allied generic forms—Tem-
nocyon, Oligobunis, lurodon (with feline and hyznoid relation-
ships), in addition to those above named—becomes the dominating,
if not the only, type in the Pliocene, where also we meet with the
earliest existing species, the wolf and coyote (Western Territories
of the United States). The Post-Pliocene deposits contain the re-
mains of the wolf, fox, and dog.*

* Mr. J. A. Allen has recently described a species of extinct dog (Pachy-
eyon robustus) from Ely Cave, Lee County, Virginia, which in many respects
departs widely from the type of any of the ordinary wild or domesticated
races. In its general proportions, the shortness of the legs, &c., it more
nearly approaches the badgers. Its geological horizon has not been absolutely
determined,

BEARS. 389

The Arctoidea, or ursine division of the Carnivora, includes the
bears (Urside), weasels (Mustelidie), raccoons (Procyonide), and the
singular panda (Ailurus fulgens), from the Himalaya Mountains,
whose connection with the true bears is established by the Thibetan
Ailuropus.

The bears, whose range embraces practically the whole of the
continents of North America and Eurasia, comprise some ten or
more species, most of which fall under the division Ursus proper.
Among the better known of these are the American grizzly (Ursus
horribilis), from the Western United States and British Columbia;
the circumpolar white or polar bear (U. or Thalassarctos mariti-
mus); the brown bear-(U. arctos), the common species of Europe
and Asia, which also appears to be identical with the common
American or black bear (U. Americanus), and to which the (Hima-
layan) Isabelline and Syrian bears (U. Isabellinus and U. Syriacus)
are nearly related; the Japanese bear (U. Japonicus); the Indo-
Malaysian sun-bear (U. or Helarctos Malayanus); and the sloth-
bear (Melursus labiatus), from India and Ceylon. A solitary species
(U. Crowtheri) is found on the African continent (Atlas Mountains),
and likewise but a single one in South America, the spectacled
bear (Tremarctos ornatus), from the Peruvian and Chilian Andes.
The last is, according to Giinther,*’ undistinguishable in its dental
characters from a species inhabiting the island of Formosa.

Two species of bear, the Ursus Arvernensis and U. Etruscus,
are known from the Pliocene deposits of Europe, which, with the
forms described from the Siwalik Hills, constitute the oldest mem-
bers of the genus with which we are acquainted. The complete
absence of ursine remains from the American Tertiary deposits
would seem to indicate that the existing New World representa-
tives of the family were a recent introduction, a supposition
strengthened by the discovery of the remains of the grizzly, as a
contemporary of the great cave-bear (U. speleeus), in the European
Post-Pliocene deposits. Of forms most nearly related to the true
bears are Arctotherium (Pliocene or Post-Pliocene of Buenos Ayres)
and Hyznarctos (Upper Miocene and Pliocene of Europe and India),
which last, by way of Dinocyon and Amphicyon, would seem to
effect a direct transition to the dogs. It thus appears that Amphi-
cyon lies at the converging point of both family lines.

The Procyonide are all members of the New World fauna, and

390 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

comprise the raccoons (Procyon), from most parts of North and
South America; the coatis (Nasua), Mexico to Paraguay; kinkajou
(Cercoleptes), Mexico to Peru and Brazil; and the bassarids (Bas-
saris), from the warmer regions of the United States and Mexico.
The family, as represented in the genus Procyon, dates from the
Pliocene period.

The Mustelide, whose numerous representatives are spread over
the greater part of all the continental areas with the exception of
the Australian, comprise among better-known forms: Lutra, the
otters, whose range embraces nearly the whole of the continents of
Eurasia and North America, with parts of South America and
Africa; Enhydris, the North Pacific sea-otter (California—Japan) ;
Nutria, the South American west coast sea-otter (California to
Chiloe); Meles, the true badger (North Europe to Japan and China) ;
Taxidea, American badger; Mellivora, the African and Indian
ratels; Mephitis, the skunk, whose range comprises the entire tract
included between Canada and the Strait of Magellan; Ictonyx, the
African zorilla; Mustela, the martens, boreal forms of both the
Eastern and Western Hemispheres; * Putorius, the weasels, which
are distributed over the greater part of the Northern Hemisphere,
and enter into tropical Africa and South America; and Gulo, the
wolverine or glutton, whose habitat in America extends from about
the fortieth to the seventy-fifth parallel (Melville Island), and in
Eurasia from Lithuania to Kamtchatka and the Arctic tundras.
In the martens are included the Asiatic sable (Mustela zibellina)
and the American sable (M. Americana), the range of the latter ex-
tending over the greater part of the American continent north of
the fortieth or forty-fifth parallel of latitude. Other well-known
forms are the Eurasiatic pine-marten (M. martes), and the pekan
or fisher (M. Pennanti), which is still extensively distributed over
the American continent north of the fortieth parallel of latitude.
Of the weasels proper (Putorius) the true or common weasel (P.
vulgaris) and ermine (P. erminea) are held in common by the
northern regions of Europe, Asia, and America, the true ferret or
polecat (P. feetidus) is Eurasiatic, and the mink, comprising the

two species, P. lutreola and P. vison, both Eurasiatic and American.
The total number of fossil forms referable to the Mustelide is

* Martes flavigula, the Indian marten, is distributed from the southern
slopes of the Himalayas to Ceylon and Java.

SEALS, SEA-LIONS. 391

very limited. The glutton, badger, otter, marten, and ermine oc-
cur in the Post-Pliocene deposit of Europe, while in the equivalent
American series we have species of Galictis and Mephitis. Taxidea,
Lutra, and Mustela are Pliocene in North America, and Mellivora
in India (Siwalik Hills).

The fourth group of the Carnivora, the Pinnipedia or seals,
comprise three very distinct families: 1. Otaridee, the eared or fur-
seals, sea-lions, with about nine species, whose habitat is the tem-
perate and cold waters of the southern oceans (as far north as the
Galapagos Islands) and the North Pacific (south to California). No
species is known from the North Atlantic. To this group belongs
the highly-prized northern fur-seal (Callorhinus ursinus), which was
at one time abundant along the greater part of the American coast
between Alaska and Lower California, but is now rapidly disap-
pearing, although still very abundant among the Prybilov or Fur-
Seal Islands; the species appears to be found also along the coasts
of Kamtchatka and the island of Saghalien. Of the sea-lions,
commonly so-called, the best-known species are the northern sea-
lion (Eumetopias Stelleri), whose range extends from Behring
Strait to California and Japan, and the Californian or black sea-
lion (Zalophus Californianus), the familiar animal of the harbour
of San Francisco. The common species of the west coast of South
America is the southern sea-lion (Otaria jubata). Other species of
the family, popularly known as sea-bears, whose domain covers
much of the southern seas, from South America to Africa and New
Zealand, are referred to the genus Arctocephalus. 2. The Tri-
chechide, walruses, containing a single species, the walrus or morse
(Trichecus rosmarus), whose habitat is the icy waters of the Arctic
regions of North America (from Labrador), Europe, and Asia.
The animal appears not to exist on the American coast between the
ninety-seventh and one hundred and fifty-eighth meridians of longi-
tude, nor on the Eurasiatic coast between the one hundred and
thirtieth and one hundred and sixtieth meridians. East of the
Yenisei it is very rare. The North Pacific form is by some authors
considered to be a distinct species (T. obesus). 8. Phocide, the
earless or true seals, which are almost universally distributed over
the temperate and colder portions of the globe. One species, the
monk-seal (Monachus albiventer) inhabits the Mediterranean and the

392 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

waters of the Canary Archipelago, and an allied form (M. tropicalis)
the shores of the West India islands and Florida. The species of
the Caspian Sea (Phoca Caspica) is by many authors identified with
the common harbour seal of the North Atlantic and Pacific oceans
(P. vitulina), and the seal of Lake Baikal (P. Sibirica) with the
northern ringed-seal, P. foetida. The greater number of the south-
ern forms are generically distinct from the northern, of which last
about one-half have a circumpolar distribution. It has been thus
far impossible to determine the exact range of the different species
of seal, but it appears that, of the northern forms, the harbour-seal
is the most widely distributed. On the American coast it has been
noted as far south as New Jersey and the Santa Barbara Islands,
California, and is reported to have been also observed near Beaufort,
North Carolina. Along the European coast it is not rare off the
coasts of Spain and France, and is even said to occasionally enter
the Mediterranean. The most northerly species appears to be the
ringed-seal, which has been met with considerably beyond the
eighty-second parallel of latitude. The Greenland or harp-seal
(P. Groenlandica) appears to be a permanent inhabitant of the St.
Lawrence River. The more aberrant forms of the family are the
hooded-seal (Cystophora cristata), from the colder parts of the
North Atlantic,* and the sea-elephants (Macrorhinus), of which
there are two generally recognised species, one of which (M. an-
gustirostris) appears to be confined to the coasts of California and
Western Mexico, and the other, the southern sea-elephant (M.
elephantinus or leoninus), to the waters of the southern oceans
(Patagonia, Juan Fernandez, Kerguelen Land, Macquarie Island).
The former species is now almost completely exterminated.

With the exception of some doubtful fragments described from
European museums, the only unequivocal remains of Otaride have
thus far been described from the Pliocene deposits of Victoria,
Australia, and the Post-Pliocene of New Zealand. The remains of
the walrus have been found in the Post-Pliocene deposits of various
parts of North America—south to New Jersey and South Carolina
—while in Europe its representatives appear to be traced back to
the Pliocene, or even late Miocene, period. Most of the so-called
trichecoid remains, however, have been shown by Van Beneden to

* An individual of this species was obtained in November, 18838, at Spring
Lake, New Jersey (Brown, ‘‘ Am. Naturalist,’’ xvii., p. 1191).

MONKEYS. 393

belong to animals having no close relationship with the walruses.
The only undoubted phocine fragment found in any American
formation of older date than the Quaternary belongs to a form
described from the Miocene of Virginia as Phoca Wymani. In
Europe, especially in the Antwerp Basin, remains of the family
are abundant, and in living and extinct genera (Phoca, Palxo-
phoca, Callophoca, Gryphoca, Monatherium, Prophoca) extend back
through the Pliocene to the later Miocene period. Leith Adams
has described a species of Phoca from the Miocene calcareous strata
of Gozo, near Malta.

Extinct Carnivora of Uncertain Position.—Under the order
Creodonta Professor Cope has united a number of generalised Euro-
pean and American carnivore types, which differ in many essentials—
greatly reduced cerebral hemispheres, absence of scapho-lunar bone,
ungrooved astragalus—from the true Carnivora, and whose direct
affinities are at once with these last, the marsupials and insectivores.
They are regarded as the primitive carnivores, inasmuch as from
these two at least of the great modern groups—the Ailuroidea
(cats) and Cynoidea (dogs)—are claimed to be directly derived.
Of the four extinct families that are referred here, the Miacida
(Miacis, Didymictis), Oxyenids (Oxyzna, Palzonyctis), Mesony-
chide (Mesonyx), and Hyznodontide (Hynodon), the first three
are restricted to the Eocene period (beginning with the Lower
Eocene), while Hyznodon is both Upper Eocene and Lower Mio-
cene. The Miacide and Oxyzenide are considered to be the ances-
tral forerunners of the dogs and cats respectively, a union between
the latter and the civets being seemingly effected by the genus
Proviverra. Here, perhaps, may also be referred the European Arc-
tocyon, one of the oldest forms of Tertiary mammals known.

Primates (Monkeys and Man *).—Naturalists usually recog-
nise three distinct groups of the quadrumanous section of the
Primates: the monkeys or apes of the New World (Platyrhina),
the apes of the Old World (Catarhina), and the lemurs or half-
monkeys (Lemuroidea), inhabitants of both continental and insular
Asia and Africa. In the broader aspects of their distribution the
members of this order may be said to be restricted to a zone
included between the thirtieth parallels of north and south lati-
tude, although a limited number of forms pass slightly beyond

* The consideration of man is not entered into in this work.

394 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

these boundaries ; they are, therefore, essentially tropical in habit.
To what extent, however, climate alone is efficient in determin-
ing this distribution still remains to be ascertained, as it is well
known that certain forms, most intimately related to species in-
habiting the torrid lowlands, appear to habituate themselves to
regions of opposite climatic conditions, or where a fairly rigourous
winter prevails. Semnopithecus schistaceus has been observed in
the Himalayas at an elevation of 11,000 feet, sporting among the
garlands of a winter’s snow, while a second species of the same ge-
nus, 8. Roxellane, and a macaque (Macacus Thibetanus), steadily
inhabit the snow-clad mountains of Moupin, Thibet, at a nearly
equal altitude. The most northerly apes known are the two spe-
cies last mentioned, a species from Japan (Macacus speciosus), and
the Barbary ape of the Rock of Gibraltar (Macacus inuus), but it is
a little doubtful whether the last is truly indigenous to the region
which it now inhabits. The southern limit in the Old World is
the region about the’ Cape of Good Hope, the home of the chac-
mas. In the New World no form is positively known to pass north
of the twentieth parallel of latitude in Southern Mexico (Ateles vel-
lerosus, a species of spider-monkey), but it is by no means improb-
able that a more northerly extension may be reached by some spe-
cies; * the American forms being exclusively arboreal in habit, their
southern extension will necessarily be determined by the limit of
forest growth, which, excepting along the Andean slopes, is in about
the thirtieth parallel of latitude, beyond which line no monkeys
are known.

It is a circumstance of some little importance, as bearing upon
geographical distribution in general, that certain continental isl-
ands, as the West Indies, apparently so well adapted in their natural
physical conditions to the development of the members of this group
of animals, should be entirely deficient in them ; the same holds true
with New Guinea, and, indeed, with the entire continent of Australia.
Madagascar, while largely supplied with the lemurs, or half-mon-
keys, is wholly wanting in the apes proper. Long-continued isola-
tion of the tracts under consideration is, doubtless, the primary, if

* According to a statement of M. Sallé, made some twenty-five years ago,
monkeys (probably a species of Ateles) were found as far north as the upper
Tampico, or up to about latitude 23° (Sclater, “‘ Nat. Hist. Review,’’ 1861, p.
509).

AMERICAN MONKEYS. 395

not the only, cause of this deficiency. At the same time, it is not
quite as easy to account for the present northern limitation. In
Mexico, for example, as far as we are able to judge of the general
character of the environment, or of the physical conditions govern-
ing it, a much more northerly extension might have been assumed
than is actually found; but, possibly, the matter of a particular form
of food-supply may have something to do with restriction in this
quarter. The semi-continent of Europe, again, whose only simian
inhabitant is the Barbary ape already mentioned, in view of the
fact that at one time it was the home of various forms of ape, offers
another instance of a region apparently suited to the wants of
these animals, yet practically entirely deficient in them ; but here,
doubtless, the extermination was a part of the general extermina-
tion which removed so many of the more distinctive types of Mio-
cene and Pliocene mammals into other regions, whatever the exact
cause may have been.

The New World monkeys are generally all included in two fam-
ilies : the Cebide, with several sub-families, monkeys with thirty-
six teeth, and the Hapalide, or marmosets, monkeys with thirty-
two teeth. The former comprise the sapajous (Cebus), which may
be taken as the representative genus of American monkeys, the
woolly monkeys (Lagothrix), spider-monkeys (Ateles, and the re-
lated Eriodes), howlers (Mycetes), sakis (Pithecia and Brachyurus),
night-monkeys or douroucoulis (Nyctipithecus), squirrel-monkeys
or saimiris (Chrysothrix), and the related Callithrix. The total
number of species known is between seventy and eighty, of which
about twenty are sapajous, fifteen spider-monkeys, ten howlers, and
about an equal number members of the genus Callithrix.

The extensive equatorial forests of the Amazon and Orinoco,
and their tributaries, constitute par excellence the home of the
American monkeys, but the majority of the genera have a very ex-
tended range, appearing in one or more species throughout the
greater portion of the tract covered by the entire family. This is
more particularly the case with the sapajous, spider-monkeys,
howlers, and callithrixes. The range of the species, on the other
hand, is not infrequently very sharply defined, as, for example,
when a natural barrier, offering insurmountable obstacles to fur-
ther migration, suddenly interposes itself. Examples of such
limitation, as brought about by the dominant water-courses of the

396 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

equatorial forests, have already been noticed in treating of specific
distribution in general (pp. 23, 24). The number of species found
in, and north of, the Isthmus of Panama is ten, of which only one,
the spider-monkey already referred to, extends into Mexico ; My-
cetes villosus, the Guatemalan howler, or mono, has thus far been
found only in Guatemala and Honduras. It is a little surprising
that the range of only two of the species—the black-faced spider-
monkey (Ateles ater) and one of the night-apes (Nyctipithecus vo-
ciferans) extends beyond Colombia in South America.

None of the South American monkeys appear to pass west of
the Andean chain of mountains south of Ecuador, and even north
of the Peruvian boundary the number of such transgressional forms
is very limited. Indeed, even among the wooded slopes, a habita-
tion along the basal line of the mountain axis seems to be much
preferred. The greatest altitude at which monkeys were observed
by Tschudi in Peru was 3,000 feet (Lagothrix Humboldtii) ; Ateles
ater and Cebus robustus were found at 2,500 feet. On the other
hand, Godman and Salvin state that in the district of Vera Paz, in
Guatemala, the mono or howler is most abundant at an elevation of
6,000 feet ; and on the volcano of Atitlan, in the same country, Mr.
Salvin found troops of the Mexican spider-monkey (Ateles vellero-
sus) in the forest region of 7,000 feet elevation.

The range of the marmosets and oustitis (Hapalidée) is nearly
coextensive with that of the monkeys proper, but no form is thus
far known to pass beyond the Isthmus of Panama;* Midas Geof-
froyi alone inhabits the Isthmus. The species, of which there are
some thirty or more referable to two genera (or sub-genera), Midas
and Hapale, are most numerous in the equatorial forests.

Of the Old World Quadrumana, the anthropoid apes (Simiinz),
which include the gorilla, chimpanzee, gibbon, and orang, acquire
special importance by reason of their high structural organisation.
In the sum of all their characters, the gorilla probably stands the
highest, although by many naturalists this place is conceded to the
chimpanzee. Only one species of gorilla (Troglodytes gorilla) has
thus far been positively determined, but not impossibly other
forms may inhabit the interior of the African continent. The rec-
ognised habitat of the species is the west coast of Africa a few de-

* Midas rufiventer, erroneously described as coming from Mexico, is a Bra-
zilian species (M. labiatus).

GORILLA, CHIMPANZEE, BABOONS. 397

grees on either side of the Equator, or the forest region drained by
the Gaboon, Muni, Fernand-Vaz, and Ogowai rivers. Much uncer-
tainty still remains as to the number of species of chimpanzee, but
most naturalists seem inclined to unite all the variously designated
forms, either actually found living or reported to be such, into a
single species, Troglodytes niger, whose habitat extends from the
west coast (Gambia—Benguela) through the heart of the continent
to the central lake region.

The Asiatic anthropoid apes are the gibbons (Hylobates) and
orang (Simia satyrus), the latter restricted to the forests of the
islands of Borneo and Sumatra. The gibbons, or long-armed apes,
which probably comprise a dozen or more species, are confined to
South-Eastern Asia, and some of the larger islands of the Eastern
Archipelago. On the continent they range from the Brahmaputra
River, in Assam, to the Malay Peninsula, and eastward to the region
about Canton, China (Hylobates pileatus); the Chinese species is
also found in the island of Hainan. The better-known forms are the
siamang (H. siamanga), the largest member of the genus, from Su-
matra, hoolock (H. hoolock), the most northern form (Assam, Ben-
gal), and lar (H. lar), from Siam, the Malay Peninsula, and Su-
matra.

Of the non-anthropoid Quadrumana of the Cld World the most
numerous in point of species are the dog-apes (Cynopithecine)—
green-monkeys, macaques, drills, baboons, &c. The long-tailed
forms of the genus Cercopithecus are exclusively African, and com-
prise all the more graceful monkeys of the continent that have been
variously designated guenons, green-monkeys, and white-nosed
monkeys. Collectively, they range over the greater part of the
tracts included between the Gambia and Congo Rivers on the west
and Abyssinia and the Zambezi on the east. The mangabeys, some-
times separated as a distinct genus (Cercocebus), are West African,
as is also the talapoin (Miopithecus talapoin). Almost equally dis-
tinctive of the African region are the dog-faced baboons of the
genus Cynocephalus, which have a very general distribution
throughout the continent, extending also into the adjoining tracts
of Asia (Arabia). Among the better-known members of this group
are the mandrill and drill (C. maimon or mormon, and C. leuco-
phaus), both from the west coast (Guinea) ; the baboons proper
(C. babuin), whose habitat extends from Abyssinia and Kordofan

398 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

into the wilds of the interior ; the nearly related and rock-inhabit-
ing chacma (C. porcarius) and sphinx (C. Sphinx), from the south
and west of the continent respectively ; and the hamadryas (C,
hamadryas), whose home is constituted principally by the coast
mountains of Abyssinia and Southern Nubia, and the littoral of
Western Arabia. A somewhat aberrant form, the gelada (C. gela-
da), differing from the other baboons in the non-terminal position
of the nostrils, and hence sometimes constituted into a distinct ge-
nus (Theropithecus), inhabits the highlands of Abyssinia at an
elevation, according to Schimper, of from 10,000 to 13,000 feet.

The macaques, if we exclude the Barbary ape or magot, whose
habitat in the north of Africa and on the Rock of Gibraltar has al-
ready been noted, are exclusively Asiatic, ranging on the continent
from the Himalayas to Japan, and southward to the extremity of the
Malay Peninsula. One or more species of the group are found on
nearly all the more important islands of the Malay Archipelago, from
Sumatra to Timor. The best-known form is the common macaque
(Macacus cynomolgus), whose habitat comprises nearly the whole
of Southeast Asia, and the islands of Sumatra, Banca, Java, Bor-
neo, Celebes, Bali, Lombok, Flores, Sumbawa, and Timor. In
Java, where it ascends to a height of 5,000 feet, it is one of the
commonest of animals, and has been brought into a general condi-
tion of domestication. Other well-known forms of the group are
the Rhesus-monkey (M. Rhesus), whose home is British India,
especially the wooded tracts of the lower Himalayas, and the
wanderoo (M. Silenus), from the forest region of Malabar. The
former has been observed to ascend the Himalayas to an eleva-
tion of upwards of 10,000 feet, and even during the winter it is
said to dwell habitually in the snow-clad forests about Simla. A
remarkable and somewhat aberrant form of this group, the black
macaque (M. niger), whose relationship with the African baboons
is more intimate than that of any of the other species, inhabits
Celebes (and Batchian ?); it is frequently recognised as the type
of a distinct genus, Cynopithecus.

The remaining types of Old World monkeys are usually included
in the genera Semnopithecus and Colobus, constituting the sub-
family Semnopithecine, the former of which, with probably not
less than twenty-five species, are exclusively Asiatic, and the latter,
considerably less numerous, African. Of the genus Semnopithecus,

OLD WORLD MONKEYS. 399

whose distributional area extends from Ceylon and the snow-bound
heights of Thibet (S. Roxellane) to the islands of the Malay Archi-
pelago, which properly constitute its headquarters, the better-
known species are the sacred entellus, or hoonuman (8. entellus),
from the Gangetic provinces, and the proboscis monkey (8. nasi-
cus) of Borneo. A form related to the last, characterised by an
excessively up-turned nose, is the proboscis monkey of Thibet
above mentioned (S. Roxellane).

The African Colobi are slender, long-tailed monkeys like the
Semnopitheci, from which they are barely separable, but differ in
the complete absence of the thumb. Of probably not more than a
dozen species, whose combined habitat embraces the greater part
of the African continent, from the west coast to Abyssinia and
Zanzibar, the best known, and, at the same time, probably the
most graceful and beautiful of all monkeys, is the guereza (C. gue-
reza), whose home appears to be the highlands of Abyssinia, at
elevations of from 7,000 to 10,000 feet. A closely related form is
Colobus Angolensis.

The total number of apes inhabiting the islands of the Malay
Archipelago is, according to Rosenberg,*** twenty-five, distributed
among the different islands as follows : Sumatra, twelve ; Banca,
four; Borneo, eleven; Java, five; Celebes, two; and Bali, Lombok,
Flores, Sumbawa, and Timor, each one. The rapid diminution in
the direction of the Australian continent, which is entirely deficient
in the animals of this class, is very marked. Only one form, the
common macaque, is common to all the islands; Sumatra holds
only one species in common with Java, whereas, surprisingly enough,
four of its species are represented in Borneo. The greater number
of the species are restricted to individual islands.

No unequivocal remains of true monkeys are known to antedate
the Miocene period, and in America they do not appear before the
late Pliocene or Fost-Pliocene. Several forms, referred to the
South American genera Cebus, Callithrix, and Hapale, and one
representing an extinct type, Protopithecus, probably allied to the
howlers, have been described by Lund from the cavern deposits of
Brazil. Protopithecus Boneriensis is founded upon a number of
incisor teeth obtained by Ameghino in the neighbourhood of the
city of Buenos Ayres. No quadrumanous remains other than those

400 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

referable to the lemurs, or to a type, Laopithecus (Miocene), stand-
ing intermediate between these and the Cebidz, have as yet been
discovered on the North American continent. To the extent of
our present knowledge, therefore, the type of the Old World mon-
keys appears to have had no representatives in the Western Hemi-
sphere.

Numerous remains of Quadrumana are found in the Tertiary de-
posits of France, Germany, Switzerland, Italy, and Greece, indicat-
ing for these animals a much broader distribution in past periods of
time than they now enjoy. Several of these forms are referred to
existing genera, such as the Miocene Colobus grandevus,. from
Steinheim, Wirtemberg, and the Pliocene Macacus priscus and
Semnopithecus Monspessulanus, from Montpellier, France. <A
macaque (Macacus Plioczenus) has also been cited from Essex, Eng-
land, and several forms have been described from the Val d’Arno,
Italy. But the greater number of the more ancient species still
remain with undetermined relationships. One of the most remark-
able of these is the Dryopithecus Fontani, from the Middle Miocene
deposits of St. Gaudens, France, and the Swabian Alps, which in
stature appears to have rivalled the largest of the existing anthro-
poid apes, although probably more nearly related to the gibbon
than to any other living member of this group. Two other appar-
ently anthropoid forms of somewhat smaller dimensions have been
described from the nearly equivalent deposits of Sansan, France,
and Elgg, in the Canton of Zurich, Switzerland, as Pliopithecus an-
tiquus and P. platyodon respectively ; these are by some authors
considered to be more nearly related to the group of the Semno-
pithecine, or even to the macaques, while by others, as Ritimeyer
and Lydekker, they are referred to the modern genus Hylobates.
Of still more doubtful relationship are the singular Mesopithecus
Pentelici, from the Mio-Pliocene of Pikermi, Greece, which in its
cranial and dental features most nearly approaches Semnopithecus,
while in the structure of the limbs it approximates the macaques,
and the probably still less simian Oreopithecus Bambolii, from
Monte Bamboli, Tuscany.

Several species of fossil ape have been described from the Siwa-
lik Hills (Pliocene), and are by Lydekker referred to the genera
Paleopithecus, Semnopithecus, Macacus, and Cynocephalus. If
the determination in the case of the last-named genus be cor-

LEMURS. 401

rectly made, it is interesting as proving the former much further
extension of the baboons than we find at the present time. Cyno-
cephalus Atlanticus occurs in the late Pliocene or Post-Pliccene de-
posits of Algeria.

The lemurs, or half-monkeys, constitute a well-differentiated
group of the Primates, differing, indeed, in so many essential points
of structure from the type of this order as to have induced many
naturalists to elevate them to an order apart by themselves, the
Lemuroidea or Prosimiz. Their non-simian affinities are at once
with the Insectivora and Ungulata, to which they appear to be
united by many connecting ties, both recent and fossil. Upwards
of fifty more or less clearly defined (recent) species, representing a
dozen or more genera, have been referred to this group, more than
one-half of which, embracing all the typical lemurs of the genera
Lemur (some fifteen species), Hapalemur, and Lepilemur, are abso-
lutely confined to the island of Madagascar, where they inhabit the
forest region. The indrises (Indris, Propithecus), which are like-
wise confined to the Madagascan region, comprise some of the
largest of the lemurs, Indris brevicaudatus measuring upwards of
two feet in length.

The sub-family of the galagos numbers probably not less than
twenty species, distributed under the two genera Chirogaleus and
Galago, the former of which is restricted to Madagascar, while the
latter inhabits the scattered wooded tracts of the interior of the
African continent, from Senegambia to Abyssinia, and southward
to Natal ; no species is known from Madagascar. All the Asiatic.
lemurs, if we except the very remarkable tarsier (Tarsius spectrum),
the type of a distinct family, which inhabits some of the larger isl-
ands of the Malay Archipelago (Sumatra, Borneo, Celebes) and the
Philippines, and which differs from the lemurs proper, apart from
other general characters, in the large eyes and unusual elongation of
the tarsal elements of the foot, belong to the sub-family of the lories.
They constitute a limited group of small nocturnal animals, desti- °
tute of a tail, and distinguished, as far as their habits are concerned,
by their exceedingly slow movements. Hence they are frequently
termed the ‘‘slow lemurs.” Of the two Oriental genera, Nyctice-
bus, the typical slow-lemur, is distributed over Cochin China,
Siam, the Malay Peninsula, and the larger islands of the adjoining

402 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION.

archipelagos—Sumatra, Java, Borneo. Loris, with a single spe-
cies, the graceful loris (L. gracilis), is a native of Ceylon. Two
other species of the same sub-family, resembling the last in their
habits, but provided with a rudimentary tail, and with a greatly
reduced index-finger, inhabit the west coast of Africa : the potto
(Perodicticus potto) is a native of the Gaboon region and the ter-
ritory of Sierra Leone, and the awantibo (P. [Arctocebus] Calaba-
rensis) of Old Calabar.

The most aberrant form of lemur is the Madagascan aye-aye
(Chiromys Madagascariensis), an animal of about the size of a cat,
with a rodent-like dentition, and singularly elongated fingers fur-
nished with pointed claws. Fora long time the position of this
remarkable animal was misunderstood, it having been placed alter-
nately with the lemurs, insectivores, and rodents. It constitutes
the type of a distinct family, Chiromyide.

The somewhat anomalous distribution of this group of animals,
taken as a whole—their headquarters in Madagascar, with a thin-
ning out towards the west on the African continent, and their re-
appearance in Ceylon and the mainland of Asia—has suggested to
some naturalists the notion that at a former, and fairly ancient, pe-
riod of the earth’s history direct land connection existed between
these various points, bridging over the chasms that now separate
them in the way of water, and permitting of ready migration from
one region to another. For this hypothetically assumed, now
sunken, continent, Mr. Sclater has proposed the name ‘‘ Lemuria.”
In how far such a connecting land-mass may have existed in fact,
or in how far, if it actually existed, it was directly concerned with
the present distribution of the lemurs, still remains to be deter-
mined.

The earliest lemuroid remains of the Old World are probably
those of Csnopithecus lemuroides, described by Ritimeyer from
the Eocene deposits of Egerkingen, Jura Mountains, and supposed
by their discoverer to represent an animal of intermediate relation-
ships between the true lemurs and the American monkeys. This
form is not unlikely identical with a species described from the
gypsum deposits of the Paris Basin and the phosphorites of Quercy
(Oligocene) as Adapis Parisiensis—for a long time supposed to
represent an ungulate—with which, also, the Paleolemur Betillei,

LEMURS. 403

from Béduer, France, has been identified. The animals here re-
ferred to appear to have their nearest analogues among the African
lories or galagos. From certain peculiarities in the structure of
the cranium, which are supposed to represent similar structures
seen in the Ungulata, Filhol recognises in these animals an extinct
zoological type, designated the Pachylemur, which stands inter-
mediate between the true lemurs and the pachyderms. Necrolemur
antiquus and N. Edwardsi, on the other hand, from the phespho-
rites of Quercy, are considered to be true lemurs. Lemuroid forms
do not appear to be represented in any of the Tertiary formations
newer than the Lower Miocene or Oligocene.

Numerous forms, referable to the same group of animals, have
been described from the Lower Tertiaries of the Western United
States (Lemuravus, Limnotherium, Microsyops, Hyopsodus, Mixo-
dectes, Anaptomorphus, &c.). These in part indicate a transition
to the hoofed animals, while others, again, are so closely linked
with the Insectivora that they are barely, if at all, separable from
them. <A reference to some of these forms will be found in the
section following the discussion of the Insectivora. As in Europe,
no lemuroid forms are known from either the American Miocene
or Pliocene formations.

REFERENCE NOTES.

1. On the authority of Wallace. It would appear, however, from the
observations of Taczanowski (‘‘ Ornithologie du Pérou,” vol. i, p. 321, 1884),
that the bird is less rare in the region indicated than has been generally
supposed.

2. Jeitteles, ‘‘ Verhandl. d. zool. bot. Gesell. Wien,” 1862, p. 262.

.8. To this list might also be added the chipmunk, Arctic hare, lynx, wolf,
walrus, several seals, &c.

4. Allen, “ North American Pinnipeds,” pp. 609 e¢ seq.

. Allen, “ North American Rodentia,” “ U. S. Geol. Survey,” vol. xi.

. “Monograph of the Strepomatide,” p. xli, Smithson. Mise. Pub., 253.
. “Island Life,” pp. 20-22.

. Seebohm, “ Catalogue of Birds,” British Museum, v, p. 328.

8a. Since the preparation of the text a large number of additional
species, and several genera, of paradise-birds have been described from New
Guinea by Finsch, Meyer, Forbes, and others.

9. The family comprises some thirty-five or more species (Beddome,
“Ann. Mag. Nat. History,” January, 1886).

10, Gray, “ Catalogue of Edentate Mammalia,” British Museum, 1869,
p. 389.

11. Brehm, “ Thierleben,” i, p. 391.

12. “Ceylon,” ii, p.. 287.

12a. ‘Proc. Zool. Soc.,” London, pp. 221, 222.

13. Newton, “ Encycl. Brit.,” article “ Humming-Bird,” ninth ed., xii,
p. 359.

14. Mosenthal and Harting, ‘“‘ Ostriches and Ostrich Farming,” p. 28.

15. “ Geograph. Distrib. of Animals,” ii, p. 330.

16. Lyell, “ Principles of Geology,” eleventh ed., ii, p. 369.

17. “ Encycl. Brit.,” ninth ed., iii, p. 461.

18. Lyell, “ Principles of Geology,” eleventh ed., ii, p. 366.

oar ao oH

REFERENCE NOTES. 405

19. Baird, “Am. Journ. Science,” 1866 (xli), p. 840.

20, Baird, ‘‘.Am. Journ. Science,” 1866 (xli), p. 346.

21. Sharpe, ‘“ Catalogue of Birds,” British Museum, ii, p. 238.

22. Wallace, “Island Life,” p. 296.

23. Wallace, “ Island Life,” p. 253.

24, Wallace, “ Geographical Distribution of Animals,” i, p. 32. The
occurrence was noted by Mr. Lowe, who communicated the facts to Sir
Charles Lyell.

25. Wallace, “Geograph. Distrib.,” i, p. 180.

26. Wallace, “Geograph. Distrib.,” ii, p. 13.

27. Coues, “‘ Key to North American Birds,” p. 317.

28. Gould, “ Birds of Australia,” ii, p. 1.

29. “Ibis,” 1884, p.471. Two hundred sheep are said to have been
killed in a single night by a flock of these birds, at a station on Wanaka
Lake.

80. ‘Proc. Zool. Soc.,” London, 1864, p. 456.

81. Elwes, “ Proc. Zool. Soc.,” 1873, p. 648.

32. Forsyth Major, “ Zoogeographische Ubergangsregionen,” “ Kosmos,”
1884, p. 106.

83. Forsyth Major, “ Kosmos,” 1884, p. 109. Forsyth Major is in error in
quoting from Bottger that twenty-seven out of the forty reptilian and am-
phibian species inhabiting Morocco are also found in Spain; the number
stated is twenty-two (“ Abhandl. d. Senckenb. Naturf.-Gesellsch.,” xiii, 1863,
p- 146).

34. Cope, “ Bull. U. S. National Museum,” 1875; Heilprin, “ Proc. Acad.
Nat. Sciences,” Philadelphia, 1882.

35. Moseley, ‘“‘ ‘Challenger’ Reports,” “ Zoology,” ii, pp. 188, 189.

36. Wyville Thomson, ‘“‘ Depths of the Sea,” p. 454.

87. Lyman, “ ‘Challenger’ Reports,” ‘“‘ Zoology,” v, p. 327.

38. A. Agassiz, “‘ Challenger’ Reports,” “ Zoology,” iii, p. 30.

39. A. Agassiz, op. cit.

40. Milne-Edwards, “ Contes Rendus,” December 17, 1883.

41. Wyville Thomson, “ Voyage of the ‘ Challenger,’ ” ii, p. 350.

42. “ Nature,” March 20, 1884.

43. Giinther, “ Study of Fishes,” p. 305.

44, Wyville Thomson, “ Voyage of the ‘Challenger,’ ” ii, pp. 352, 353.

45. “Annals and Magazine of Natural History,” January, 1883; ‘“ Ver-
handl. d. k. k. geol. Reichsanstalt,” 1882, No. 4.

46. “Nature,” xxvi, p. 560.

47, “ Bull. Museum Comp. Zoology,” Cambridge, vi, p. 153.

48. ‘ Nature,” September 3, 1885.

406 REFERENCE NOTES.

49. “Bull. Soc. Vaud.,” xiv, p. 211, 1876.

50. “ Rendic. R. Istit. Lomb.,” ser. 2, xii, p. 694.

50a. Asper and IIeuseher have quite recently shown, through the use of
a “pelagic” net, that the pelagic faunas of lakes are far more prolific in mi-
croscopic animal forms than has hitherto been supposed. A drop of water
from Lake Ziirich was estimated to contain ten individuals of Anurza foli-
acea, eight of Anurewa longispina, sixty of Ceratium hirundinella, and mill-
ions of Dinobryon forms and Asterionelle, besides various heliozoans, roti-
fers, and crustaceans. Identical results were obtained under all the most
varied conditions of light (darkness) and water, in the open lake and along
the shallower shore-line (“‘ Zoologischer Anzciger,” June 19, 1886).

51. “ Nature,” June 11, 1885.

52. “Am. Journ. Science,” 1871, p. 161.

53. “ Bull. Soc. Vaud.,” xiii, xiv, 1874, 1876. Dr. Henri Blanc enumer-
ates the following twelve species of Rhizopoda as entering into the compo-
sition of the deep-water fauna of Lake Geneva (seventy to one hundred and
twenty metres): Amoeba proteus, A. verrucosa, A. radiosa, Difflugia pyri-
formis, D. urceolata, D. globulosa, Ilyalosphenia cuneata, Arcella vulgaris,
Centropyxis aculeata, Pamphagus hyalinus, Actinophrys sol, and an unde-
termined large Difflugia. All or most of the above forms have been ob-
served by Leidy in the surface-waters of the United States, and it is re-
marked that the species indicated to be rare by Leidy are also rare in the
deep waters of the lake (‘ Bull. Soc. Vaud.,” ser. 2, xx, p. 287).

54, “Am. Journ. Science,” 1871.

55. “ Anniversary Address, London Geol. Soc.,” 1881.

55a. Probably the most striking and convincing evidence indicating con-
vergent modification is presented by the Australian fauna, where, among
the numerous implacental forms, we have such remarkable reproductions
of the distinctive types seen among the Placentalia, aithough based upon
an entirely different type of structure, and arising independently of the
other.

56. “ Paleontographical Soc. Reports,” 1884.

57. “Ann. Mag. Nat. Hist.,” 1874, xiii, p. 222.

58. Heilprin, “ Proc. Acad. Nat. Sci.,” Philadelphia, March 4, 1884.

59. “ Anniversary Address, London Geol. Soc.,”.18&1.

60. Medlicott and Blanford, ‘Geology of India,” part i, p. 282.

61. Seeley, “‘Q. Journ. Geol. Soc.,” London, 1883.

62. Dawson, “Am. Journ. Science,” third ser., xx, pp. 408 ef seq.

63. Anodonta Jukesii, from the Old Red Sandstone of Ireland. TPro-
fessor Hall recognises in the Cypricardites Catskillensis of Vanuxem, from
the Oneonta Sandstones of the State of New York (Middle Devonian), a

REFERENCE NOTES. 407

fresh-water mussel having the general characters of Anodonta (‘‘ Science,”
New York, December 11, 1880).

64.

“ Review of the Non-Marine Fossil Mollusca of North America,” “U.

S. Geol. Surv.,” third annual report, 1881-’82.

65.

Smith, “ Proc. Zool. Soc.,” London, 1881; Crosse, “ Journal de Con-

chyliologie,” 1881; Bourguignat, “ Mollusques Terr. et Flur. du Lac Tan-
ganyika,” August, 1885.

66.

67.

68.

69.

70.

tke

. “Paleontologia Indica,” ser. ix, 1875.

. “Paleontologia Indica,” 1865.

. “ Kreidebildungen von Texas,” 1852.

. “Zeitschr. d. deutsch. geol. Ges.,” 1870, pp. 191-251.

. “Jahrb. d. k. k. geol. Reichsanstalt,” 1871, p. 524.

. “ Paleontologia Indica,” “ Cephalopoda of Kutch,” ser. ix, p. 237.

. “Kreideb. v. Texas,” pp. 22-25.

. “Smithsonian Miscell. Pub.,”’ vii.

. “Jahrb. d. k. k. geol. Reichsanstalt,” 1878, p. 44.

. “ British Assoc. Reports,” 1884, p. 555.

82.

. Bronn’s “ Klassen und Ordnungen d. Thier-Reichs, Protozoa.”
84.

ogy,” i
85.

Marshall, “‘ Ann. Mag. Nat. History,” December, 1883.
Richthofen, “ China,” iv.

“Q. Journ. Geol. Soc.,” London, 1878, pp. 568 e¢ seq.

“ Manuel de Conchyliologie,” p. 144 (1881).

Tryon, “ Structural and Systematic Conchology,” i, p. 159.
Carpenter, on te authority of Fischer, op. cié., p. 168.

“ Anniversary Address, Geol. Soc.,” London, 1862, p. xiv.

From the data furnished by Brady, ‘“ ‘ Challenger’ Reports,” “ Zool-

From the data furnished by Brady, “ ‘ Challenger’ Reports,” “ Zool-

ogy,” ix.

86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.

“ Challenger’ Reports,” “Zoology,” vi, p. 132.

““¢ Challenger’ Reports,” “ Zoology,” ii, “‘ Corals,” pp. 132, 133.
Duncan, “ Q. Journ. Geol. Soc.,” London, xxvii, p. 437.
Duncan, “ Q. Journ. Geol. Soc.,” London, xxix, p. 561].
Duncan, “ Q. Journ. Geol. Soc.,” London, xxvi, p. 313.

“ Denkschr, d. k. k. Akad.,” Vienna, 1872, p. 199.

“Q. Journ. Geol. Soe.,” London, xxvi, p. 311.

“Q. Journ. Geol. Soc.,” London, xxxii, p. 343.

Zittel, “‘ Handbuch der Paleontologie,” i, pp. 717-720.

“‘ Manuel de Conchyliologie,” pp. 173 et seq.

Ellsworth Call, ‘‘ Bull. U. 8S. Geol. Survey,” xi (1884), p. 43.
Thesaurus Siluricus; Thesaurus Devonico-Carboniferus.

408 REFERENCE NOTES.

98. “ Handbuch der Paleontologie,” ii, p. 320.

99. “Encycl. Brit.,” ninth ed., vi, p. 663 (“ Crustacea”),

100. Bronn’s “‘ Klassen und Ordnungen des Thier-Reichs,” v, p. 1073.
101. Hall, “ Pennsylvania Second Geol. Survey,” 1884, PPP, p. 29.
102. McLachlan, in Nares’s “‘ Voyage to the Polar Sea,” ii, p. 234.
103. “Trans. Asiatic Soe. of Japan,” November, 1885.
104. “ Nature,” December 24, 1885.
105. “Mem. Boston Soc. Nat. History,” April, 1885.

106. Scudder, “ Mem. Boston Soc. Nat. History,” April, 1885, p. 355.
107. “ Nature,” January 29, 1885, p. 297.
108. “ Voyage to the Polar Sea,” ii, p. 1220.
109. “Study of Fishes,” pp. 307-3811.
110. Giinther, “ Study of Fishes,” pp. 270, 271.
111. “Science,” May 28, 1884.

112. Filhol, in “Science,” May 23, 1884.
113. “Science,” May 23, 18S4.
114. “ American Naturalist,” March, 1885, p. 289.
115. “ Journ. Asiatic Soc. Bengal,” 1864, p. 544.
116. Leydig, “ Abhandl. d. Senckenb. Naturf.-Gesell ,” xiii, 1883.
117. Boéttger, “ Abhandl. d. Senckenb, Naturf.-Gesell.,” xiii, 1883.
118. Bosea, “ Bull. Soe. Zool. de France,” 1880.
119. Bedriaga, ‘ Bull. Soc. Natural.,” Moscow, 56, 1881.
120, “ Ann. Mag. Nat. Hist.,” January, 1886.
121, Woodward, “ Geol. Magazine,” November, 1885.
122. “ Paleontologia Indica,” ser. x, iii, p. 146.
123. “Q. Journ. Geol. Soc.,” London, August, 1885.
124, “ Eneycl. Brit.,” ninth ed., xv, p. 399.
125. Dobson, “ Monograph of the Insectivora,” 1882.
126. “ American Naturalist,” May, 1885, p. 467.
127. Dobson, “ Catalogue of the Cheiroptera, British Museum,” p. xxx.
128. “Am. Journ. Science,” April, 1886.
129. “ Zoologischer Anzciger,” June, 1883.
130. “Q. Journ. Geol. Soc.,” London, 1878, p. 419.
131. “Trans. Am. Philos. Society,” January 18, 1884.

132. ‘“ Proc. Zool. Soc.,” London, p. 443.
183. “ Zoologischer Garten,” xxiii (1882), pp. 111-115.

Aard-wolf, 383.
Abyssal zone, 262.
Acanthomys, 355.
Accipenser, 68, 69.
Aceratherium, 368.
Acervularia, 249.
Achenodon, 374.
Achatinella, 261.
Acidaspis, 146.
Acomys, 364,
Acris, 309.
Acrobata, 99.
Acrodus, 300.
Acrosaurus, 320.
Acrotreta, 205.
Acteeonidee, 166.
Actinia, 240, 242.
Actinocrinus, 151.
Adapis, 348, 402.
Addax, 377.
Adder, 321.
Adoeus, 315.
ABzoceras, 166, 267.
Alurodon, 336, 388.
ffl.rogale, 385.
/Epyornis, 333.
ZEtobatis, 800.
Agama, 316, 318.
Ayaricia, 248.
Agelaius, 66.
Agnostus, 140, 276-278.
Agouti, 361.

PNA Box.

Agriocherus, 383.
Ailuropus, 389.
Ailurus, 389.
Alactaga, 358.
Alaudidee, 66.
Alea, 69.
Alcedinide, 66.
Alces, 381.
Aleyonaria, 251.
Alepocephalus, 298.
Alctornis, 331.
Alk, 69.
Alligators, distribution of, 328, 329.
Alligator-gar (Lepidosteus), 301.
Allorisma, 271.
Allosaurus, 162.
Alpaca, 375.
Alveolites, 143.
Amadine, 88.
Amaltheus, 267.
Amblypoda, 367.
Amblypterus, 302.
Amblyrhynchus, 317.
Amblystoma, 306.
Amia, 68, 301.
Amiurus, 68.
Ammodiscus, 240.
Ammonites, 137, 166, 192, 200, 222-
294, 266, 267.
Amphibia, 45, 305.
Amphibos, 378.
Amphicyon, 383, 389.

410

Amphioxus, 299,
Amphipoda, 272.
Amphisaurus, 160.
Amphisbeenia, 319.
Amphitherium, 535.
Amphitragulus, 381.
Amphiuma, 306, 311.
Amplexus, 151.
Amynodon, 368.
Ananchytes, 168.
Anaptomorphus, 849, 403.
Anatinidee, 168.
Anchitherium, 371, 372.
Anchovy (Engraulis), 295.
Ancistrodon, 323.
Ancyloceras, 168, 267.
Ancylotherium, 338.
Ancylus, 261.
Andrenidie, 284.
Anemone, 242.

Angler (Lophius), 294, 295.

Annelida (deep-sea), 109.
Anoua, 378.

Anodonta, 148, 209.
Anolis, 317.

Anomia, 211.
Anomodontia, 159.
Anoplotherium, 382.
Ant, 283.

Ant-eater, 337.
Antechinus, 99.
Antedon, 136.

Antelopes, 84, 377, 378.
Anthracomartus, 151, 286,
Anthracopupa, 150, 208.
Anthracotherium, 375.
Anthropoid apes, 396.
Antilocapra, 377.
Antipathidee, 242.
Antrozous, 351.

Anura, distribution of, 307.

Apatornis, 330.
Apes, 396.
Aphanapteryx, 333.
Aphelops, 368,

INDEX.

Apidae, 284.
Apiocrinide, 111.
Apiocrinus, 166.
Aplocerus, 377.
Aporrhaide, 166.
Apteryx, 29, 101.
Aptornis, 333.
Apus, 207, 273.
Aquila, 79.
Aracarie, 78.
Arachnactis, 242.
Arachnecthra, 102.

Arachnids (of lakes), 181; geol. dis-

tribution of, 285.
Arcade, 148, 268, 271, 272.
Arcestes, 156, 267.
Archeegosaurus, 310.
Archeocidaris, 151.
Archeomys, 364.
Archeopteryx, 330.
Archeospherina, 134.
Archipolypoda, 286,
Arctocebus, 402.
Arctocephalus, 391.
Arctogale, 92.
Arctomys, 359, 364.
Arctonyx, 97.
Arctotherium, 389.
Arechnothera, 94, 102.
Argiope, 255.
Argonauta, 20, 122, 226.
Argus, 95, 97.
Argynnis, 280, 281.
Arietites, 166.

Arius, 104.
Armadillo, 5, 24, 337.
Aromcchelys, 314,
Artamide, 104.
Artemia, 212.
Arvicola, 356, 365,
Asaphus, 146, 277.
Aspidonectes, 314.
Ass, 870.
Assiminea, 261.
Astacus, 207, 275.

Astartidee, 148, 166, 271, 272.
Asteroidea (deep-sea), 111.
Asterolepis, 302.

Astreea, 247-249.
Astreidee, 144,

Astrangia, 248.

Atalapha, 349, 351.

Atax, 126.

Ateles, 394-396.
Atherines, 104.

Atherura, 362.

Athyris, 145.

Atlanta, 120, 122.
Atlantosaurus, 161.
Atrypa, 145, 214.
Auchenia, 375, 376.
Aurelia, 122.

Aurochs, 379.

Australian fauna, anomalies of, 9.

Australian realm, 97.
Aviculide, 148, 271.

Axis, 381.

Axolotl, 306.

Aye-aye, 402.

Azores, birds of the, 7, 48.

Babbling-thrush, 72, 94, 107.
Baboon, 397.

Babyrousa, 374.

Baculites, 168, 267.

Badger, 390.

Baikal, Lake, fauna of, 212.
Bairdia, 207, 273, 274.
Balena, 341.

Balenoptera, 341, 344.
Balenotus, 345.

Baltimore bird, 66, 79.
Bandicoot, 99.

Barbary ape, 394, 395.
Barbel, 68, 291.
Barbus, 68.

Barracuda (Sphyrena), 294.
Barramunda, 103. >

Barriers affecting migration, 41.
Bascanium, 323, 324.

INDEX. 411

Basilisk, 317.

Bass (Labrax), 294.

Bassalian province, 299.

Bassaris, 390.

Bathmoceras, 192.

Bathyactis, 110, 243.

Bathycrinus, 111.

Bathyergus, 357.

Bathygnathus, 160.

Bathyophis, 298.

Bats, distribution of, 349.

Battocrinus, 151.

Bear, 4, 27, 389.

Beaver, 360, 864, 365.

Bee-eater, 87, 94, 106.

Bees, 279, 284.

Beetles, 150, 279, 280, 283, 284.

Belemnitella, 168.

Belemnites, 137, 156, 168, 268.

Belemnosepia, 138, 166.

Belideus, 99, 100.

Bell-bird, 78.

Bellinurus, 278, 279.

Bellows-fish (Centriscus), 295.

Beloteuthis, 166.

Beluga, 344.

Bermudas, birds of the, 48, 51.

Bernissartia, 329.

Beroe, 240,

Beyrichia, 272.

Beryx, 294, 303.

Bibos, 379.

Big-horn, 379.

Birds, American, common to Europe,
46; European, common to Amer-
ica, 48; dispersal of, 45; migra-
tions of, 47; oceanic journeys
of, 47; Arctic, 70; geological dis-
tribution of, 330; of the Holarctic
realm: of the Eurasiatic division,
65; of the North American, 66;
of the Neotropical realm, 77-79 ;
of the Ethiopian realm, 87, 88;
of the Oriental realm, 94, 95; of
the Australian realm, 100-102;

412

of the Polynesian realm, 104; of
the Mediterranean region, 105,
106.

Bison, 379.

Blarina, 346.

Blastocerus, 380.

Blattarie, 283.

Blenny (Blennius), 293.

Blessbok, 84.

Blind-worm (Anguis), 315, 320.

Blow-fish (Cheetodon), 296.

Blue-bird, 28, 66.

Boa, 825-327.

Boar, 374.

Boat-bill, 81.

Boavus, 327.

Bobolink, 66.

Bombinator, 312.

Bonasa, 66.

Bonito, 297.

Bos, 379.

Bothriolepis, 302.

Bower-bird, 101.

Brachiopoda, age of, 188; deep-sea,
113; distribution of, 214, 252.

Brachymetopus, 151, 277.

Brachyops, 311.

Brachypyge, 275.

Brachyura, 112, 275.

Brady pus, 337.

Brahmatherium, 377.

Branchiosaurus, 310.

Branchipus, 212.

Breaks, geological, 192.

Brisinga, 111.

Brittle-stars, 111, 166.

Broad-bill, 95.

Brontosaurus, 161.

Brontotherium, 372.

Brush-turkey, 95, 101.

Buansuah, 387.

Bubalus, 378.

Bucapra, 580.

Buccinide, 169.

Buccinum, 262.

INDEX.

Buffalo, 878.

Buffelus, 378.

Bufo, 307, 312.

Bugs, 279, 280, 284.

Bulbul, 94, 107.

Buiimus, 261.

Bull-fineh, 65, 70.

Bull-head (Cottus), 68, 287, 2938, 294.

Bungarus, 322, 325.

Bunodonta, 3738.

Bunting, 66, 70.

Buprestites, 283.

Burbot (Lota), 288.

Bushbok, 84, 89.

Bustard, 66, 72.

Butterflies, 279, 280, 284; Arctic, 51,
70; on Chimborazo, 51.

Buzzard, 66.

Cacatua, 162.
Cacatuide, 88, 102.
Cachalot, 342.
Celogenys, 361.
Ceenopithecus, 402.
Cainotherium, 382.
Calamary, 268.
Calamoichthys, 89, 291.
Calliste, 78.

Callithrix, 395, 399.
Callophoca, 393.
Callorhinus, 391.
Calostylis, 144.
Calymene, 146, 278.
Calyptorhynchus, 102.
Camarasaurus, 169.
Cambrian fauna, 135.
Camel, 15, 16, 31, 87, 875, 376.
Camelopardalis, 376, 377.
Campephagide, 104.
Camptonotus, 162.
Canace, 66.
Cancellaride, 169, 270.
Cancroma, 81.

Canis, 386-388.
Capercaillie, 66.

INDEX. 413

Capito, 81.

Capra, 380.

Capreolus, 381.

Caprina, 169.

Capromys, 360.

Caprotina, 169.

Capulus, 138, 207, 269.

Capybara, 361, 365.

Carabidze, 69, 281, 284.

Caracal, 384.

Carboniferous fauna, 150.

Carcharias, 297, 300.

Carcharodon, 297, 300.

Cardiide,, 148, 166, 271, 272.

Cariacus, 381.

Cariama, 88.

Carinaria, 122.

Carnivora, distribution of, 383.

Carp, 68, 89, 290.

Caryophyllia, 243, 244.

Cassicus, 79.

Cassididee, 270.

Cassidulina, 235.

Cassowary, 101, 332.

Castor, 360, 364, 365.

Castoroides, 365.

Cat, 27, 383.

Catarhina, 393.

Caterpillar-eater, 72, 94, 104.

Cat-fishes (Siluridee), 68, 80, 89, 288-
290.

Cathartine, 66.

Catopterus, 302.

Catostomus, 68.

Cattle, 379.

Caulaster, 136.

Cave-bear, 389.

Cave-lion, 384.

Cavy (Cavia), 361.

Cebus, 395, 399.

Centetes, 346.

Centetodon, 348,

Centipedes, 285, 286.

Centrarchide, 68.

Centrocercus, 66.

Cephalaspis, 149, 301.

Cephalopoda, deep-sea, 113 ; geologi-
cal distribution, 265. (See Mor-
LUSCA.)

Cephalophus, 89.

Cephalopterus, 78.

Ceratiocaris, 273.

Ceratites, 267.

Ceratodus, 103, 291, 302, 304.

Ceratophrys, 310, 312.

Ceratoptera, 297.

Ceratorhinus, 368.

Cercocebus, 397.

Cercolabes, 362.

Cercoleptes, 390.

Cercopithecus, 397.

Cerianthus, 242.

Ceriornis, 66.

Cerithiide, 166.

Certhiadee, 107.

Certhiola, 78.

Cervalces, 382.

Cervulus, 381.

Cervus, 380, 381.

Ceryle, 106.

Cetacea, distribution of, 341.

Cetiosaurus, 161.

Cetotherium, 345.

Chacma, 398.

Chafiinch, 70.

Chalicotherium, 372.

Chalk, nature of, 237.

Chama, 73.

Chameleon, 316, 318.

Chamide, 272.

Chamois, 21, 377.

Characinide, 80, 290.

Charina, 322.

Chasmorhynchus, 78.

Chatterer, 78.

Cheetah, 384.

Cheiroptera, distribution of, 349.

Cheirurus, 146.

Chelone, 313, 315.

Chelonia, distribution of, 313.

414 INDEX.

Chelopus, 314.
Chelydee, 314.
Chelydra, 313-315,
Chevrotain, 376.
Chilabothrus, 326.
Chimera, 293-295.
Chimpanzee, 397.
Chinchilla, 361.
Chipmunk, 359.
Chirogaleus, 401.
Chirolepis, 149.
Chiromys, 402.
Chironectes, 334.
Chironomid, 283.
Chiton, 207, 260,
Chlamydosaurus, 318.
Cheenohyus, 374.
Cheropotamus, 375.
Cheeropsis, 26.
Cheeropus, 99.
Cholepus, 337.
Chomatodus, 300.
Choristoceras, 156, 268,
Chromides, 290.
Chrysaétos, 79.
Chrysemys, 814.
Chrysochloride, 346.
Chrysothrix, 395.
Cicada, 284,
Cidaride (deep-sea), 111.
Cidaris, 157, 166, 168.
Cinosternum, 314.
Cistudo, 313-315.
Civet-cats, 385.
Cladocera (of lakes), 126.
Cladocora, 248.
Cladophyllia, 247.
Cleodora, 122.
Clepsy drops, 154.
Clepsysaurus, 160.
Clidastes, 169.
Climate, effect of, upon distribution,
35-40.
Climatic zones (geological), 222.
Cnemiornis, 333.

Clotho, 88.

Clydonites, 156.
Clymenia, 156, 267.
Clypeus, 166.

Coassus, 380.

Coati, 390.

Cobitoids, 291.

Cobitus, 68.

Cobra (Naja), 322, 825,
Coccosteus, 149, 301.
Cochliodus, 300.
Cochloceras, 156, 268.
Cockatoo, 88, 95, 101.
Cock-of-the-rock, 78.
Cockroach, 147, 282, 283.
Cod (Gadus), 287, 293, 294, 296, 299.
Ceecilia, distribution of, 306, 810.
Celacanthus, 301, 302.
Ceelodon, 339.
Ceerebide, 78.
Coleoptera, 96, 279, 280, 288, 284.
Colias, 280, 281.
Collyrites, 166.

Colobus, 399, 400.
Colocollo, 383.

Colonies, geological, 231.
Colossochelys, 315.
Colubers, 67, 322-324, 327.
Columba, 102.
Columbide, 66.
Colymbus, 69.
Compsognathus, 162.
Condor, 79, 80.

Condor, Californian, 73
Condylarthra, 368.
Condylura, 347.

Coney, 33, 867.

Conger, 294, 295.
Conide, 169, 270.
Conocephalus, 146.
Conocoryphe, 276.
Conocyathus, 246.
Conodonts, 299.

Contia, 323.

Conurus, 78, 88.

INDEX. 415

Copepoda (of lakes), 126.

Copperhead, 323.

Coral-fishes (Pomacentride), 296.

Coralline zone, 262.

Corallium, 252.

Coral-reefs, ancient, 249.

Corals, deep-sea, 110, 242; distribu-
tion of, 240.

Coral-snake, 325.

Corax, 300.

Corbicula, 211.

Corbula, 211.

Cormorant (fossil), 330-332.

Cornufer, 307. -

Coronelia, 321, 325.

Corsac, 388.

Corvidee, 65.

Corvus, 79.

Coryphodon, 367.

Corythaix, 87.

Cotingide, 78.

Cottide, 68.

Cotton-rat, 356.

Couguar, 19, 883.

Cow-bird, 66.

Coyote, 388.

Coypu, 360.

Crabs (deep-sea), 112.

Cracide, 78.

Crane (fossil), 332, 333.

Crania, 207, 255, 257.

Craspedocephalus, 79.

Creeper, 78, 107.

Cremastosaurus, 820,

Creodonta, 393.

Cretaceous fauna, 168.

Cricetodon, 865.

Cricetomys, 357.

Cricetus, 357, 364.

Cricket, 284.

Crinoidea, 185; deep-sea, 111.

Crioceras, 168, 267.

Cristellaria, 188.

Crocidura, 346.

Crocodiles, distribution of, 327, 328.

Crossbill, 65.

Crotalus, 322, 323.

Crow, 65, 79, 104; fossil, 332.

Crustacea, deep-sea, 112; pelagic,
120, 122; of lakes, 126,131; dis-
tribution of, 272.

Cryptobranchus, 306, 311.

Cryptoprocta, 385.

Ctenacanthus, 152, 300.

Cuckoo, 104.

Cuckoo, ground, 73.

Cuon, 387.

Cupido, 66.

Curassow, 78.

Curculionites, 283.

Curlew (fossil), 332.

Cusceus, 100.

Cyanea, 122.

Cyathocrinus, 151.

Cyathophyllum, 143, 151, 249,

Cyclas, 264.

Cyclolobus, 267.

Cycloclypeus, 234.

Cyclophis, 323.

Cyclophthalmus, 151.

Cycloturus, 337.

Cynocephalus, 397, 400, 401.

Cynogale, 92, 385.

Cynomys, 359.

Cynopithecus, 398.

Cypreidee, 169, 270.

Cypridina, 207, 273.

Cyprinidee, 68, 89.

Cyprinodon, 80.

Cypris, 274.

Cypsclide, 66.

Cyrtoceras, 139, 145, 190, 192, 265,
266.

Cystignathide, 309.

Cystophora, 392.

Cythere, 207, 278, 274.

Dactylethride, 310.
Dakosaurus, 162, 329.
Dalmania, 146, 199, 277, 278.

416 INDEX.

Dama, 381. Dikelocephalus, 146.
Duapedius, 302. Dimetrodon, 154,
Dasornis, 331. Dimorphodon, 164.
Dasyprocta, 361. Dinichthys, 149, 302.
Dasypus, 337. Dinictis, 385.

Dasyuride, 99. Dinoceras, 367.
Dawsonella, 150, 208. Dinocyon, 389.

Decapoda, 274. Dinornis, 333.

Decp-sea fauna, 109. Dinosauria, 160, 161, 169, 172, 203.
Deep-sea zone, 262. Dioplotherium, 340.

Deer, 27, 380. Diplograptus, 145.
Delphinapterus, 342, Diploria, 247-249.
Delphinus, 342. Dipnoi, 302.
Deltocyathus, 243-246. Diprotodon, 336.
Dendrerpeton, 310. Dipsadide, 325.
Dendrobates, 310. Diptera, 279, 280, 283, 284.
Dendrocolaptide, 78. Dipterus, 149, 301.
Dendrodus, 301. Dipus, 358.

Dendrohyrax, 33, 87. Discina, 145, 207, 255, 257.
Dendrolagus, 99. Discinisca, 253.
Dendromys, 356. Discinocaris, 273.
Dendrophide, 325. Discoidea, 168.
Dendrophiyllia, 248. Discrytus, 146, 282.
Dentalium, 207, 269. Diver, 69.

Dermatochelys, 313. Dodo (Didus), 333.
Desmatotherium, 369. Dodo-pigeon, 104.
Desmognathus, 306. Dog, 27, 386, 387.
Devonian fauna, 146. Dog-fish (Acanthias), 293-295, 300.
Dhole, 387. Dolichonyx, 66.

Diadectes, 154. Dolichosoma, 310, 311.
Diadophis, 328. Dolichotis, 361.

Diatryma, 331. Dolium, 260.

Dicxide, 94, 104. Dolphin, 342, 343.
Diceras, 272. Dolphin (Corypheena), 297.
Dichobune, 382. Dormice, 357.
Dichograptus, 145. Dorycrinus, 151.
Dicotyles, 374. Douroucouli, 395.
Dicroccrus, 381. Draco, 318.

Dictyoearis, 273. Drepanide, 104.
Dicynodon, 159. Drepanodon, 384.
Dideiphys, 334, 335. Dromeus, 101.
Didunculidx, 104. Dromeornis, 333.
Didymictis, 393. Dromatherium, 335.
Didymograptus, 145. Dromicia, 99.

Diemyctilus, 306. - Dryiophide, 325.

Dryolestes, 335.
Dryopithecus, 400.
Duck (fossil), 332, 333.
Duck-bill, 333.
Dugong, 339.
Dzizgetai, 370.

Eagle, 66, 79, 88; fossil, 332.
Echidna, 333, 334.

Echinide (deep-sea), 111.
'Echinobrissus, 166.
Echinoderms, 111, 166.
Echinogale, 346.
Echiomyide, 360. =
Edentata, distribution of, 336.
Edmondia, 271.

Edwardsia, 242.

Fels, 104, 292, 296, 303.
Eider-duck, 69.

Elachoceras, 367.

Eland, 84.

Elaphis, 321, 323, 824,
Elaphodus, 72.

Elapidee, 322, 325.
Elasmobranchii, 299.
Elasmognathus, 369.
Elateride, 284.

Electric eel (Torpedo), 80, 294.

Elephant, 18, 36, 87, 206; distribu-

tion of, 365, 366.
Elephant-shrews, 346.
Elk, 381, 382.
Emarginula, 269.
Emballonura, 351.
Emberiza, 66, 70.
Empedocles, 154.
Emu, 101; fossil, 332.
Emyde (Emys), 314, 315.
Enaliornis, 330.
Encrinus, 157.
Endoceras, 145, 190.
Enhydris, 390.
Entellus-monkey, 399.
Entomodon, 348.
Eobasileus, 367.

INDEX.

Eohippus, 371, 372.
Eohyus, 374.
Eoscorpius, 151, 286.
Eotherium, 340.
Eozoon, 134, 196.
Equus, 369-371.
Erethizon, 362.
Erinaceus, 347.
Eriodes, 395.
Ermine, 4, 390.
Erycide, 322.

Ery ops, 155.
Esocidee, 68.

Esox, 69.

Estheria, 207, 273.
Esthonyx, 348.
Estrild, 88.
Ethiopian realm, 82.
Euclastes, 315.
Eugercon, 283.
Eulabes, 94.
Eumetopias, 391.
Euomphalus, 148, 269.
Euphoberia, 151, 286.
Euphonia, 78.
Euplectella, 110.
Euplocamus, 97.
Euproops, 278.
Eupsammide, 144.
Eurasiatic region, fauna of, 60.
Euryapteryx, 333.
Eurylemide, 95.
Eurypterus, 148, 278, 279.
Eurysternum, 315.
Eusmilus, 385.
Euteenia, 328, 524.
Evotomys, 656.
Exogyra, 168.
Extracrinus, 166.

417

Falcon, 19, 66, 69, 104; fossil, 880.

Fallow-deer, 380, 381.
Families, distribution of, 29.

Faunas, variation in, 3-6; migrations
of, 13; origination of, 15, 178;

418

relation of past to present, 11,
12.

Favia, 247.

Favosites, 143, 215, 249.

Felis, 383, 384.

Felsinotherium, 340.

Ferret, 390.

Fiber, 357.

Finch, 65, 88, 100.

Fin-whale, 341.

Fisher, 390.

Fishes, distribution of, 287; shore,
293 ; pelagic, 297; deep-sea, 298 ;
phylogeny of, 305; earliest, 142;
of the Holarctic realm, 68; of
the Neotropical realm, 80; of the
Ethiopian realm, 88, 89; of the
Australian realm, 103; of the
Polynesian realm, 104.

Fish-hawk, 19.

Flabellum, 243-246.

Flamingo, 31, 106; fossil, 331, 332.

Flat-fishes, 294.

Flies, 279, 280.

Florissant, insects of, 284.

Flounder, 294.

Flower-pecker, 94, 104.

Fly-catcher, 65, 79, 88, 100.

Flying-foxes, 350, 352.

Flying-garnard (Dactylopterus), 297.

Flying-herring (Exoccetus), 297.

Flying-lemurs, 345.

Flying-lizard, 318.

Flying-opossum, 99.

Flying-squirrels, 358, 359.

Foraminifera (deep-sea), 109; dis-
tribution of, 234.

Formicide, 284.

Fowl (Gallus, fossil), 332.

Fox, 4, 387, 388.

Francolin, 88, 106.

Fringillide, 66, 88, 100.

Frog-fish, 297.

Frogs and toads, dispersal of, 45;
distribution of, 307, 312.

INDEX.

Fulgorina, 283.
Fundulus, 290.
Fungia, 247-249.
Fungiacyathus, 242.
Furciter, 380.
Fuside, 169.
Fusulina, 236.
Fusus, 262, 263, 269.

Galago, 401.

Galapagos, birds of, 6, 49.

Galaxias, 288, 292.

Galbulide, 78.

Galecyunus, 888.

Galeocerdo, 297, 300.

Galeopithecus, 345.

Galeospalax, 248.

Galerites, 168.

Galerix, 348.

Galesaurus, 159.

Galictis, 90.

Galidia, 90.

Gallus, 95.

Gannet (fossil), 332.

Ganocephala, 310.

Ganoids, 291, 299, 300.

Garden-mouse, 18.

Gasteropoda, deep-sea, 113; pelagic,
120; geological distribution of,
268. (See Mottusca.)

Gasterosteide, 68.

Gastornis, 330, 331.

Gavial, 328, 329.

Gazelle, 84, 377, 378.

Gecko, 316, 318.

Gelada, 398. -

Gemsbok, 84, 377.

Genera, distribution of, 26.

Genet, 385.

Geococecyx, 73.

Geomys, 365.

Geophaps, 102.

Geophilus, 286.

Geosaurus, 320.

Gerbillus, 355,

INDEX. 419

Gerephemera, 146, 282. Grosbeak, 65.

Ghaur, 379. Ground-pigeon, 102.
Gibbon, 387. Ground-squirrel, 359, 365.
Giraffe, 376, 377. Grouse, 66, 72; fossil, 330, 333.
Girvanella, 240. Gryphea, 168.
Glandaria, 188. Gryphoca, 393.
Glass-snake, 316. Guacharo, 18.

Glaucus, 129. Guan, 78.

Glis, 357. Guanaco, 375.
Globicephalus, 342. Guenon, 397.
Globigerina, 109, 188, 235, 236. Guereza, 399.
Globigerina ooze, 236, 237. Guevi, 84.

Glutton, 390. Guinea-fowl, 88.
Glycimeride, 168, 272, - Guinea-pig, 361.
Glyptodon, 338, 339. Gull (fossil), 331, 332.
Glyptolepis, 149, 301. Gulo, 390.
Glyptosaurus, 320. Gurnard (Trigla), 294.
Gnu, 84, 377. Guynia, 144, 240.
Goats, 28, 379, 380. Gymnodactylus, 316, 318.
Goatsucker, 104. Gymnotus, 80.
Gobiesocidee, 295. Gymuura, 347.

Goby, 104, 292. Gypactus, 71.

Godwit (tossil). 330. Gyps, 106.
Golden-mole, 346. ' Gyracanthus, 152.
Golden-pheasant, 66. Gyrichnites, 286.
Goldfinch, 65, 70. Gyroceras, 137, 266.
Gomphoceras, 145, 266. Gyrodus, 302.
Goniastrea, 247. Gyroporella, 237.
Goniatites, 137, 145, 267.

Goniobasis, 69. Hadrosaurus, 169.
Goose (fossil), 332, 333. Hag (Myxine), 294, 299.
Gopher, 365. Hake (Merlucius), 294, 296.
Gorgonella, 251. Haleampa, 242.
Gorgonia, 251. Haleyon, 106.

Gorilla, 396. Haleyornis, 331.

Goura, 102. Haliaétus, 79.
Graculavus, 330. Halicore, 340.
Grammysia, 271. Halitherium, 340.
Grampus, 343. Halobates, 120.
Granatocrinus, 151. Halysites, 143, 215, 249.
Graphularia, 251. Hamadryas, 398.
Graptolites, 144, 208, 215. Hamites, 168, 267.
Greenland, insects of, 70. Hamster, 357.
Griffithides, 151, 277. Hang-nest, 66, 79.

Grizzly-bear, 389. Hapale, 396, 399.

420 INDEX.

Hapalemur, 401.

Haplodon, 360.
Haplophlebium, 150.
Haplophorus, 339.
Haplophyllia, 144, 240.
Hares, 21-23, 70, 362, 364, 365.
Harlequin snake, 322.
Harpoceras, 166, 267.
Harpy, 79.

Harrier (fossil), 331.
Hartebeest, 84.

Hatteria, 320.

Haw-finch, 65.

Hawk, 66.

Hedgchogs, 347,

Helagras, 327.

Helaletes, 369.

Helarctos, 329.

Heliastraea, 247.

Helicide, 69.

Helicoceras, 168.

Heliolites, 143, 249.

Helix, 261, 262.
Helladotherium, 877.
Heloderma, 317.

Helodus, 800.

Hemiaspis, 278.
Hemicaulodon, 340.
Hemicidaris, 158, 166.
Hemidactylus, 316, 318.
Hemiptera, 279, 2S0, 283, 284.
Hermit-crabs (deep-sea), 112.
Heron, 104; fossil, 331, 332.
Herpestes, 385.

Herring (Clupea), 293, 294, 296, 303.

Hesperomys, 355, 365.
Hesperornis, 330.
Heterodon, 90, 323, 324.
Heterodryas, 90.
Hill-tit, 94, 107.
Hipparion, 371, 372.
Hippidium, 371.
Hippopotamus, 26, 373.
Hippurites, 169, 208.
Hirundinide, 65.

Hoazin, 81.

Hog, 874.

Holarctic realm, 57, 73.

Holbrookia, 317.

Holectypus, 166.

Hlolocystis, 144.

Holopea, 148.

Holops, 329.

Holoptychius, 149, 301.

Holothuroidea (deep-sea), 109, 112.

Homeosaurus, 320.

Homotaxis,. 227.

Homothetus, 146, 282.

Honey-guide, 87.

Honey-sucker, 72, 87, 102, 104, 106,
107.

Hoolock, 397.

Hoonuman, 399.

Hoopoe, 106.

Hoplophoneus, 385.

Horned-toad, 817.

Horse, 369; extinction of, in Ameri-
ca, 204, 206.

Horse-mackerel (Caranx), 294, 296.

Horseshoe bat, 353.

Hortulia, 326.

Hound (Mustelus), 294.

Howler, 395, 396.

Humming-birds, 17, 38, 73, 77.

Humpback, 341.

Ilyemoschus, 376.

Hyenarctos, 389.

Ilyznodon, 393.

Hyalonema, 110.

Hy bodus, 800.

Hydrobia, 209.

Hydrocheerus, 361, 365.

Hydromys, 356.

Hydrophide, 321.

Hydrophilites, 283.

Hydropotes, 72.

Hydrosaurus, 320.

Hyena, 885, 386.

Hyla, 307.

Hylerpeton, 310.

INDEX. 421

Hylobates, 397, 400.
Hylonomus, 310.
Hymenocaris, 140, 273.
Hymenoptera, 279, 280, 288, 284.
Hyopotamus, 375.
Hyopsodus, 348, 403.
Hyotherium, 374.
Hyperamina, 240.
Hyperodapedon, °320.
Hypodiadema, 158.
Hyposaurus, 329.
Hypsiprymnopsis, 334.
Hypsiprymnus, 99.
Hyrachyus, 369.
Hyracoidea, 87, 367.
liyracodon, 368.
Hyracotherium, 371, 3872.
Hyrax, 33, 87.

Hystrix, 362, 365.

lanthina, 120, 122.

Ibex, 28, 380.

Ibis (fossil), 382.

Iceland, insects of, 70.

Icelus, 293.

Ichneumon, 385.

Ichthyornis, 330.

Ichthyosauria, 162, 172.

Icteridx, 66, 79.

Icticyon, 386.

Ictitherium, 385.

Ictonyx, 390.

Idiocetus, 345.

Iguana, 317, 320.

Iguanavus, 320.

Iguanodon, 162, 169.

Impeyan, 66, 95.

Indicatoridz, 87.

Indris, 401.

Infusoria (pelagic), 124; of lakes,
127, 181.

Inia, 341.

Insectivora, distribution of, 845.

Insects, dispersal of, 51; distribution
of, 279; earliest, 146.

To, 69.

Trrisoride, 87.

Isacis, 348.

Isastreea, 157. 247.
Ischadites, 236.
Ischypterus, 302.
Ischyromys, 365.
Island faunas, 6, 7.
Isolation, effects of, on faunas, 6.
Isophyllia, 249.
Isopoda, 272.
Issiodoromys, 364.
Ithygrammodon, 376.

Jacamar, 78.

Jackal, 387.

Jaguar, 383.

Jaguarundi, 383.

Jararaca, 79.

Jays, 25, 26.

Jerboa, 358.

John Dory (Zeus), 294, 295.
Juan Fernandez, birds of, 50.
Jungle-fowl, 95.

Jurassic fauna, 161.

Kangaroo, 99, 336.
Kangaroo-rat, 99.

Keeling Islands, birds of the, 50.
Kiang, 370.

King-fisher, 66, 104, 106 ; fossil, 331.
Kinglet, 66.

Kinkajou, 390.

Kite, 66; fossil, 332
Klipspringer, 84.

Koala, 99.

Kogia, 342.

Koninckia, 257.

Koodoo, 84, 377.

Kutorgina, 255,

Labyrinthodontia, 310.
Lacerta, 315, 320.

Lacertilia, distribution of, 315.
Lachesis, 79.

422

Lagena, 236, 240.

Lagidium, 361.

Lagomys, 362, 364.

Lagopus, 66, 69, 70.

Lagostomus, 361.

Lagothrix, 395, 396.

Lake fauna, 126.

Lamellibranchiata (deep-sea), 113;
geological distribution of, 271.
(See Mo.txusca. )

Laminarian zone, 262.

Limmerveier, 71.

Lamna, 297, 300.

Lamprey, 68, 299.

Laniide, 65.

Laophis, 327.

Laopithecus, 400.

Laopteryx, 330.

Laornis, 330.

Laosaurus, 162.

Lar, 397.

Laramie formation, 2038, 210.

Lark, 66.

Lark-bunting, 65.

Lates, 288, 289.

Latimeandra, 247.

Laurentian (/) fauna, 134.

Leaf-nosed bats, 352. _

Leda, 207.

Leiodon, 169.

Leipoa, 101.

Leiotrichide, 94, 107.

Lemming (Myodes), 357.

Lemuravus, 403,

Lemuria, 87, 402.

Lemuroideca, 393.

Lemurs, distribution of, 401.

Leopard, 18, 883, 384.

Leperditia, 140, 272.

Lepidoptera, 96, 279, 280, 284.

Lepidosiren, 80, 302, 304.

Lepidosternon, 319.

Lepidosteus, 68.

Lepidotus, 302.

Lepilemur, 401.

INDEX.

Leptictis, 348,

Leptobos, 378.

Leptolepis, 302, 303.

Leptosomus (fossil), 331.

Lepus, 362, 364, 365.

Lestodon, 339.

Libe!lulidee, 283.

Light, penetration of, into water, 118,
128.

Lima, 207.

Limacina, 260.

Limide, 166, 272.

Limna, 69, 261, 264.

Limnohyus, 372.

Limnophis, 327.

Limnotherium, 403.

Limulus, 207, 278.

Ling (Molva), 69, 294.

Lingula, 137, 139, 145, 253, 255, 257.

Lingulella, 137, 189, 146.

Lingulepis, 255.

Linnet, 65, 70.

Linota, 70.

Lion, 36, 384.

Listriodon, 369.

Lithentomum, 146, 282.

Lithophis, 327.

Lithostrotion, 151, 215, 249.

Littoral fauna, 124.

Littoral zone, 262.

Lituites, 145.

Lizards, dispersal of, 45; distribu-
tion of, 315.

Llama, 375.

Loach, 288.

Lobites, 267.

Lophiodon, 369.

Lophohelia, 243, 244.

Lophophorus, 66.

Lophopsittaeus, 833.

Lophotragus, 72.

Loris, 402.

Lota, 69.

Loxodon, 865.

Loxolophodon, 367.

INDEX. 423

Loxonema, 148, 269. Mammoth, 205, 366.
Lucinidee, 166, 272. Manakin, 78.
Lump-sucker (Discobolus), 293. Manatee, 339, 340.
Lung-fish, 80, 89, 103, 291, 302. Mandrill, 397.
Luscinia, 65, 70. Mangabey, 397.
Lutra, 390. Manicina, 248.
Lycena, 280, 281. Manis, 336.
Lycalopex, 387. Manucodia, 101.
Lycaon, 386. Marmoset, 396.
Lynx, 3838, 384. Marmot, 359, 364.
Lyre-bird, 101. Marsipobranchii, 299.
Lytoceras, 166, 207. Marsupialia, distribution of, 334.
Marten, 390.
Macaque (Macacus), 394, 398, 400. Mastodon, 366.
Macaw, 78, 88. M’doqua, 84.
Machairodus, 384. Meadow-mice, 356.
Mackerel, 297. Medlicottia, 156, 267.
Macrauchenia, 378. Meduse (deep-sea), 110; pelagic, 120.
Macropetalichthys, 149. Megalichthys, 301.
Macropodide, 98, 336. Megalonyx, 339.
Macropoma, 302. Megalornis, 331.
Macropus, 99. Megalosaurus, 162, 169.
Macrorhinus, 392. Megapodius, 95, 101, 104.
Macrornis, 331. Megaptera, 341.
Macroscelides, 346. Megatherium, 338.
Macrotherium, 338. Megerlia, 255.
Macrura, 275. Melanerpeton, 311.
Mactride, 168. Melania, 166, 209.
Madrepora, 242, 247-249, Meleagris, 66.
Meeandrina, 247, 248. Meles, 390.
Magpie, 28. Meliphagide, 102, 104.
Malacoclemmys, 314. Mellivora, 390.

Mammalia, dispersal of, 43; distri- | Melonites, 151.
bution of, 333; Arctic, 70; of the | Meniscoessus, 335.
Holaretic realm : of the Eurasiatic | Menobranchus, 306.
division, 59-61, 69-72; of the Menodus, 372.
American division, 62-65, 72,73; | Menopoma, 306, 311
of the Neotropical realm, 74-77, Menuridee, 101.

80, 81; of the Ethiopian realm, Mephitis, 390.

83-87, 89, 90; of the Oriental | Merganser (fossil), 332.

realm, 91-94, 96, 97; of the Aus- Meriones, 355.

tralian realm, 98-100; of the Merops, 87, 94, 106.

Polynesian realm, A038, 104; of Merychyus, 382.

the Mediterranean region, 105. Mesohippus, 371, 872.
Mammalian descent, line of, 176. Mesonyx, 393.

424

Mesopithecus, 400.

Mesoplodon, 342, 345.

Metridium, 242.

Metriorhynchus, 329.

Miacis, 393.

Mice, 354, 355, 364.

Micraster, 168.

Microlabis, 151.

Microlestes, 334.

Micromeryx, 381.

Microsyops, 348, 403.

Midas, 396.

Migration of birds, 39, 40; of fishes,
41; of reptiles, 41; of quadru-
peds, 40, 41.

Minivet, 94.

Mink, 390.

Miohippus, 371, 372.

Mionornis, 333.

Miopithecus, 397.

Mixodectes, 403.”

Mniotiltide, 66.

Mole (Talpidee), 347.

Mole-rats, 357.

Molgophis, 311.

Mollusea, dispersal of, 53; longevity
of, 543 Arctic, 70; of lakes, 131;
fresh-water, earliest, 209; of
American coast, 216, 217; of
British coast, 216; of French
coast, 216; of Iberian coast, 216;
of Norwegian coast, 216; Japan-
ese, 216, 217; Mediterranean,
216, 218; Indo-Pacific, 217; Ant-
arctic, 219; distribution of, 258 ;
indicating climate, 224.

Molluscan provinces, 258.

Moloch, 318.

Molossus, 349.

Molothrus, 66.

Monachus, 3891.

Mongoose, 385.

Monitor, 319.

Monkeys, 75; distribution of, 393.

Monk-fish (Rhina), 295.

INDEX.

Monoceros, 344.
Monograptus, 145.
Monopleura, 169.
Monotremata, distribution of, 333.
Montlivaltia, 158.
Moose, 881.
Morelia, 326.
Mormyride, 89.
Moropus, 338.
Morosaurus, 161.
Mosasaurus, 169.
Moschus, 380.
Motacillidee, 66.
Motmot, 78.
Mound-builder, 95, 101, 104.
Mouse-deer, 376.
Mullet, 104, 292.
Mullet-king (Apogon), 296.
Muntjac, 381.
Murchisonia, 148, 269.
Muricidee, 169, 270.
Mus, 354, 355, 364.
Muscardinus, 357.
Muscicapide, 65, 79.
Musk-deer, 380.
Musk-ox, 206, 379.
Musk-rat, 357, 365.
Musophaga, 87.
Mustela, 390.
Myacites, 209, 395.
Myide, 168.
Myliobatis, 297, 300.
Mylodon, 359,
Mynah, 94.
Myodes, 357.
Myogale, 28, 347, 348.
Myolagus, 364.
Myopotamus, 360.
Myoxidee, 357, 364.
Myriapoda, geological distribution of,
285.
Myrmecobiide, 99.
Myrmecobius, 99.
Myrmecophaga, 337.
Mysarachne, 347.

INDEX. 425

Mystriosaurus, 329.
Mytilide, 148, 166, 207, 271.

Naiadites, 209.
Narica, 269.
Narwhal, 344.
Nasua, 390.
Natica, 166, 207, 262, 269.
Nautilus, 137, 145, 192, 207, 213, 265-
267.
Neera, 263.
Necrolemur, 348, 403.
Nectarinea, 87, 94, 102, 106.
Nectarophila, 94.
Necturus, 306.
Nematocarcinus, 112.
Neobalena, 345.
Neolimulus, 279.
Neophron, 106.
Neoplagiaulax, 336.
Neotropical realm, 78.
Neritina, 166, 209, 211.
Nesokerodon, 363.
Nesokia, 355,
Nestor, 102.
Neurogymnurus, 347.
Neuroptera, 279, 282, 283.
Neurotrichus, 348.
Newt, 306.
Night-ape, 395, 396.
Nightingale, 65, 70.
Nimravus, 385.
Noctiluca, 122.
Notelephas, 366.
Nothosaurus, 159.
Notidanus, 297, 300.
Notornis, 333.
Nototherium, 336.
Nuculide, 148, 207, 263, 271.
Numidine, 88.
Nummulites, 152, 173, 189.
Nuthatch (fossil), 65, 330.
Nutria, 390.
Nycticcbus, 401.
Nycticejus, 351.

Nyctiornis, 94,
Nyctipitnecus, 395, 396.
Nylghau, 378.

Obolella, 255.

Obolus, 145, 257.
Oceanic basins, permanency of, 220.
Ocelot, 383.

Oculina, 248, 249.
Odontopteryx, 331.
Odontornithes, 330.
Oeningen, insects of, 284.
Olenus, 146.

Oligobunis, 388.

Olividie, 169, 270.
Omphyma, 143.

Onager, 370.

Onchus, 142, 300.
Onychogale, 96.
Onychoteuthis, 138.
Ophibolus, 323.
Ophiderpeton, 310, 311.
Ophidia, distribution of, 320.
Ophidiidee, 299.
Ophioderma, 166.
Ophioglypha, 166.
Ophiophagus, 322, 32d.
Ophiosaurus, 316.
Ophiura, 111.
Ophiurella, 166.
Ophiuroidea (deep-sea), 111.
Opisthocomus, 81.
Opossum, 334.

Oppelia, 267.
Oracanthus, 152.
Orbicella, 248.
Orbiculina, 234.
Orbitoides, 173.
Orbitolites, 234.
Orbulina, 109, 235-237.
Orea, 343.

Orcella, 343.

Orders, distribution of, 32.
Oreodon, 382.
Oreopithecus, 400.

426 INDEX.

Oreortyx, 66.

Orcosaurus, 32).

Organist, 78.

Oriental realm, 90.

Oriole, 106.

Ornithopoda, 162.

Ornithorhynchus, 333.

Orodus, 300.

Orohippus, 371, 372.

Orthis, 145, 255.

Orthisina, 255.

Orthoceras, 137, 189, 145, 156, 190,
192, 265, 266.

Orthoptera, 279, 283, 284.

Orthotonius, 94.

Orycteropus, 336.

Oryx, 84, 377.

Oscillatoriz, 120.

Osteolepis, 149, 301.

Osteopygis, 315.

Osteornis, 331.

Ostracoda, 126, 274.

Ostrea, 166, 168, 211, 272.

Ostrich, 32, 38, 88; American, 79;
fossil, 332.

Otaria, 391.

Otis, 66.

Otocyon, 386

Otodus, 300.

Otter, 390.

Oudenodon, 159.

Ounce, 383.

Oustiti, 396.

Ovibos, 379, 380.

Owl, 19, 66, 69, 104; fossil, 331-333.

Oxyena, 393.

Oyster, earliest, 272.

Paca, 861.

Pachycyon, 388.
Pachylemur, 403.
Pachysimia, 375.

Pacific, temperature of, 116.
Palacodon, 348.
Palearctic region, 56.

Palemon, 275.
Paloblattina, 146, 282, 283.
Paleocampa, 286.
Paleocetus, 344.
Paleocherus, 374.
Paleocircus, 351.
Paleodictyoptera, 282.
Paleolagu:, 365.
Paleoluma, 376.
Paleolemur, 348, 402.
Paleomeryx, 381.
Palzoniscus, 302.
Paleonyctis, 393.
Paleopalemon, 148, 275.
Palophis, 327.
Paleophoea, 393.
Paleophoncus, 146, 285.
Paleopithecus, 400.
Paleorbis, 208.
Paloreas, 378.
Palzornis, 88.
Paleornithide, 95.
Paleortyx, 331.
Palxoryx, 378.
Paleosaurus, 155.
Paleosiren, 311.
Paleospalax, 348.
Paleospiza, 331.
Paleosyops, 372.
Paleotherium, 371.
Paleotragus, 378.
Paleotringa, 330.
Palwozoic faunas, 156.
Palamedea, 81.
Palapteryx, 333.
Palasterina, 135.
Palechinus, 151.
Palephemera, 282, 283.
Palestine, birds of, common to Eu-
rope, 106.
Palinurus, 122.
Paludestrina, 264.
Paludina, 69, 166.
Pangolin, 336, 337.
Panochthus, 339.

INDEX.

Panther, 383, 384.

Paractis, 241.

Paracyathus, 245.

Paradise-bird, 190, 107.

Paradiseine, 100, 140, 146, 276-278.

Paradoxurus, 385.

Parahyus, 374.

Parakeet, 78, 95, 101.

Parameles, 99.

Parameryx, 376.

Parasmilia, 244.

Parasorex, 346.

Paridee, 65, 107.

Parrots, 39, 88, 95, 101; fossil, 332.

Partridge, 66, 69, 72.

Pastor, 94, 106.

Pauxi, 81.

Pavo, 97.

Pavonaria, 251.

Pavonia, 247, 248.

Peachia, 242.

Peacock, 95, 97.

Peccary, 5, 374.

Pecchiolia, 263.

Pecten (Pectinide), 169, 207, 263, 272.

Pedetes, 358.

Pelagic fauna (oceanic), 119; of
lakes, 127-180.

Pelagornis, 330.

Pelecan (fossil), 332.

Pelias, 71.

Pelion, 310.

Peltocaris, 273.

Peneus, 275.

Pennatulids, 251.

Pentacrinus, 157, 166.

Pentamerus, 145.

Pentremites, 151.

Perch (Perea), 68, 69, 288.

Perdix, 66.

Pericrocotus, 94.

Permian fauna, 154.

Perodicticus, 402.

Persia, birds of, common to Europe,
106. :

427

Petalodus, 300.

Petaurista, 99.

Petrogale, 99.

Petromyzon, 68.
Phacocherus, 374.

Phacops, 146.

Phalanger, 99.
Phalangistidee, 99.
Pharyngobranchii, 299.
Phascolarctos, 99.
Phascolomyidee, 100.
Phascolotherium, 335.
Phasianidee, 95, 100.
Phasianus, 66.

Phasmide, 283.

Pheasant, 66, 95, 100; fossil, 332.
Phenacodus, 368, 372.
Phillipsia, 141, 151, 277.
Philodryas, 90.

Phoea, 392, 393.
Pholadomyide, 166, 168, 272.
Phragmoceras, 145.
Phrynosoma, 317.
Phylloceras, 166, 267.
Phyllodactylas, 316, 318.
Phylograptus, 145.
Phyllopoda, 274.
Phyllornithide, 94.
Phyllostomide, 352.

Physa, 69, 261.

Physalia, 120.

Physeter, 842.

Picide, 66, 100.

Pie, 65.

Pigeon, 66, 102, 1045 fossil, 332.
Pig-rat, 355.

Pika, 28, 362.

Pike (Esox), 68, 69, 288, 303.
Pilot-fish, 297.

Pilot-whale, 343.

Pimelodus, 89, 289.
Pinacoceras, 267.

Pinna, 207.

Pipa, 310, 312.

Pipe-tish (Syngnathus), 293, 803.

428

Pipride, 78.

Pithecia, 395.
Pityophis, 828.
Placodus, 159.
Plagiaulax, 335.
Plagiodontia, 360.
Plaice, 294.
Planorbis, 69, 166, 209, 261, 264.
Plantain-eater, 87.
Platanista, 341.
Platephemera, 146.
Platidactylus, 316.
Platyceras, 148.
Platycereus, 101.
Platyerinus, 151.
Platydia, 253, 255.
Platygonus, 374.
Platyrhina, 393.
Plectrophanes, 70.
Plesiarctomys, 364.
Plesiocetus, 345.
Plesiochelys, 164, 815.
Plesiosaurus, 159, 162.
Plesiosorex, 347.
Plethodon, 306.
Pleurosternum, 815.
Pleurotoma, 262, 263.

Pleurotomaria, 138, 148, 166, 207

269.
Pleurotomide, 169, 270.
Pliauchenia, 376.
Pliohippus, 371, 872.
Pliopithecus, 400.
Pliosaurus, 162.
Ploceus, 83, 100, 104.
Plutonia, 276.
Pocillopora, 247-249.
Poebrotherium, 376.
Poephaga, 379.
Pogonodon, 385.
Polar-bear, 389.
Polecat, 390.
Polymastodon, 836,
Polynesian realm, 103.
Polyplectron, 97.

INDEX.

Polypterus, 89, 291, 301.
Polysiphonia, 241.
Polystomella, 235.
Pompadour, 78.
Pontoporia, 841.
Porcupine, 361, 362, 365.
Porcupine-fish, 297, 303.
Porgy (Pagrus), 294.
Porites, 144, 247-249.
Porpita, 120.

Porpoise, 343.

Portax, 378.

Portuguese man-of-war, 120,
Potamocheerus, 374.
Potamogale, 26, 346.
Potoroo, 99.

Potto, 402.

Pouched-rat, 357.
Pourtalesia, 112.
Pourtales Plateau, 116.
Prieostrea, 272.
Prairie-dog, 359.
Prestwichia, 278.
Primates, distribution of, 393.
Primitia, 140.

Priodon, 338.
Prionitide, 78.
Prisciturben, 144,
Priscodelphinus, 345.
Proboscidea, distribution of, 365.
Proboscis-monkey, 399.
Procamelus, 876.
Procervulus, 381.
Preeyon, 390.
Productus, 148, 214.
Proetus, 141, 151, 277.
Prong-horn, 877.
Prophoca, 393.
Propithecus, 401.
Proscorpius, 285.
Protareea, 144,
Protechimys, 363.
Proteles, 383.
Proterosaurus, 320.
Proteus, 806, 311.

Protolabis, 376.
Protolycosa, 151, 286.
Protophasma, 150, 282.
Protopithecus, 399.

Protopterus, 89, 291, 302, 304.

Prototalpa, 348.
Protornis, 331.
Protriton, 310.
Provivera, 393.
Prox, 381.
Psammodus, 800.
Psammophis, 71.
Pseudzlurus, 385.
Pseudalopex, 387.
Pseudastacus, 275.
Pseudemys, 314.
Pseudo-Neuroptera, 282,
Pseudopus, 316.
Psophia, 81.
Psittacus, 88.
Ptarmigan, 66, 70.
Pteranodon, 169.

Pteraspis, 142, 149, 299, 301.

Pterichthys, 149, 301.
Pterocles, 71.
Pterodactyl, 163, 164, 169.
Pteromys, 359.
Pteropoda (pelagic), 120.
Pteropus, 352, 353.
Pterosauria, 163, 172.
Pterygotus, 148, 278, 279.
tilocereus, 845.
Ptilopus, 102.
Ptiloris, 101.
Ptilotis, 102.
Ptychoceras, 168.
Ptychodus, 300.
Puff-adder, 88.
Pullenia, 235, 236.
TPulmonata, 269.
Pulvinulina, 2385.
Puma, 383.
Pupa, 150, 208, 212, 264.
Purpuride, 166.
Putorins, 390.

INDEX. 429

Pycnodontide, 94,
Pyecnodus, 302.
Pycnonotide, 107.
Pyranga, 78.

Pyrocystis, 122.
Pyrosoma, 120.

Pyrrhula, 70.

Pyrula, 269.

Python, 325, 326.
Pythonomorpha, 169, 172,

Quagga, 370.

Quail, Californian, 66.
Quail (fossil), 330.
Quinqueloculina, 237,

Rabbit, 363, 364.

Raccoon, 390.

Radiolaria, 109.

Radiolites, 169.

Rail (fossil), 330, 332.

Rana, 307, 808, 312.

Rangifer, 381, 382.

Rasse, 385.

Rastrites, 145.

Rat, 198, 355, 364.

Ratel, 390.

Rattlesnakes, 67, 322, 323.

Raven, 19, 79.

Ray (Raja). 293, 294, 299, 300.

Receptaculites, 236.

Red Sea, color of, 120.

Redstart, 65.

Red-wing, 66.

Regulus, 66.

Reindeer, 37, 70, 381, 382.

Reptiles, dispersal ot, 45 ; age of, 159;
distribution of (see CuELonia,
Crocopit1a, Lacrrtitta, Oput-
pia); of the Holarctie realm, 66,
67, 70, 71; of the Neotropical
realm, 79, 80; of the Ethiopian
realm, 88, 90; of the Oriental
realm, 95, 96; of the Australian
realm, 102; of the Polynesian

430

realm, 104; of the Mediterranean
region, 106.
Requienia, 169.
Rhabdoceras, 156, 268.
Rhabdophyllia, 247.
Rhamphastide, 78.
Rhamphorhynchus, 163, 164,
Rhamphosuchus, 329.
Rhea, 80.
Rhesus-monkey, 398.
Rhinoceros, 368.
Rhinochetide, 104.
Rhinodon, 297.
Rhinolophus, 352, 354.
Rhipidomys, 356.
Rhbizocrinus, 111.
Rhizodus, 301.
Rhynehocephala, 320.
Rhynchonella, 145, 165, 188, 207, 252,
255.
Rhynchosaurus, 159.
Rhytina, 340.
Rhytiodus, 340.
Rifle-bird, 101.
Right-whale (Balena), 341.
River-hog, 374.
Robin, 65.
Rockling (Motella), 294, 296.
Rocky Mountain goat, 877.
Rodentia, distribution of, 354.
Roe, 381, 382.
Rorqual, 341, 342.
Rotalia, 237.
Rotifera (of lakes), 127, 181.
Rudiste, 169, 208, 272.
Rugose corals, 143.
Rupicola, 78.
Rusa, 381.

Sable, 390.
Saccamina, 236.
Saccomys, 365.
Saccostomus, 357.
Sageceras, 156, 267.
Saiga, 377.

INDEX.

Saki, 395.

Salamander, 306, 312.
Salenidee (deep-sea), 111.
Salmon (Salmo), 68, 69, 288.
Salpa, 120.

Sandpiper (fossil), 330, 382.
Sandwich Islands, birds of the, 50.
Sanguinolites, 271.

Saniva, 320.

Sao, 146.

Sapajou, 395.

Sarcolemur, 348.
Sarcorhamphus, 73, 79.
Sauranodon, 162.
Sauropoda, 161.

Saw-bill, 78.

Saw-fish (Pristis), 300.
Scalops, 348.

Scapanus, 348.

Scaphaspis, 299, 301.
Scaphites, 168, 267.
Seaphopoda, 263.
Scarabeide, 284.
Sceleporus, 317.
Scelidosaurus, 162.
Scelidotherium, 339.
Schizopoda (deep-sea), 112.
Scincus, 320.

Sciurodon, 364.

Sciuromys, 365.
Sciuropterus, 359.

Sciurus, 358, 364, 365.
Scopelide, 297-299.
Scorpxnide, 296.
Scorpions, 285.

Scotophis, 323, 324.
Sereamer, 81.

Sculpin, 68.

Scyllium, 294, 299, 300.
Sea-anemones, distribution of, 240.
Sea-cows, 339.

Sea-devils, 297.
Sea-elephant, 392. —
Sea-fans, 251.

Sea-horse (Hippocampus), 294, 297.

INDEX. 431

Seal, 22, 891.

Sea-lion, 391.

Sea-otter, 390.

Sea-perch (Serranus), 294, 296.

Sea-urchins, 111, 168.

Secretary-bird, 88.

Selache, 297.

Sclasphorus, 78.

Selenodonta, 373, 375.

Semele, 263.

Semioptera, 107.

Semnopithecus, 394, 398, 399.

Serpentarius, 88.

Serpents, dispersal of, 45; distribu-
tion of, 320.

Serval, 384,

Sewellel, 360.

Shark, 293, 297, 299, 300.

Sheep, 379, 380.

Shrew, 345, 346.

Shrike, 65, 100.

Sialia, 66.

Siamang, 397.

Siderastraea, 249.

Siderina, 248,

Sieboldia, 306, 311.

Sigmodon, 356.

Silurian fauna, 142.

Silurida, 68, 80, 89.

Simosaurus, 159.

Siphonia, 168.

Siren, 306, 811.

Sirenia, distribution of, 339.

Siskin, 70.

Sistrurus, 323.

Sittidz, 65, 107.

Sivatherium, 377.

Skink (Eumcces), 316.

Skip-jack, 297.

Skipper, 297.

Skunk, 4, 390.

Slimonia, 148, 278.

Sloths, 337.

Smelt (Osmerus), 294, 303.

Snapper (Mesoprion), 296.

Snipe (fossil), 332.

Snow-partridge, 66.

Solenidse, 272.

Solenodon, 346.

Soles (Rkombus, Pleuronectes, Solea),
294, 296,

Solitaire (Pezophaps), 333.

Somateria, 69.

Sonoran transition region, 106.

Sorex, 346.

Spalacide, 357.

Sparrow, 65, 1975; fossil, 332.

Species, appearance of, 190; extine-
tion of, 197; distribution of, 17-
26; ancient migrations of, 220,
229.

Spelerpes, 306.

Spermophile, 359.

Sperm-whale, 341, 342.

Spherexochus, 278,

Spherulites, 169.

Sphargis, 313.

Sphenodon, 320.

Sphenotrochus, 2438.

Spheroidina, 109, 235, 236.

Spice-bird, 78.

Spider-monkey, 394, 395.

Spiders, 285.

Spiny-mice, 355.

Spiny-rats, 360.

Spirifer, 145.

Spiriterina, 165.

Spirula, 20.

Sponges (deep-sea), 110; Cretaccous,
168.

Sprat. (Clupea), 295.

Springbok, 84, 877.

Squalodon, 344.

Squaloraja, 300.

Squatina, 300.

Squirrel, 358, 365.

Squirrel-monkey, 395.

Stag, 881, 382.

Stagonolepis, 328.

Standard-wing, 107.

432 INDEX.

Staphylinide, 69, 284.

Star-fishes, 111, 135, 166.

Star-gazer (Uranoscopus), 294.

Starling, 66, 79, 94.

Steatornis, 18.

Stegocephala, 310.

Stegodon, 366.

Stegosaurus, 162.

Stellarida, 135.

Stellio, 71, 316.

Stencofiber, 864, 365.

Steneosaurus, 329.

Stephanoceras, 166, 267.

Stephanophyllia, 243, 245.

Stereognathus, 835.

St. Helena, birds of, 50.

Stickleback (Gasterostcus), 68, 288.

Stone-hateh, 107.

Stork (fossil), 332.

Strepomatidee, 24,

Streptclasma, 148.

Strigopide, 102.

Stromatopora, 145.

Strombide, 166, 169.

Strophalosia, 148.

Strophites, 148, 208.

Strophodus, 300.

Strophomena, 145.

Struthio, 79, 88.

Sturgeon (Accipenser), 66, 69, 289,
300.

Sturnide, 66, 79.

Stylacodon, 335.

Stylarza, 144.

Stylina, 247.

Stylodon, 835.

Stylonurus, 278, 279.

Sucker, 68.

Sucker (Catostomus), 289, 291.

Sugar-bird, 78.

Summer-redbird, 78.

Sun-bird, 94.

Sun-fish (Orthagoriscus), 68, 297.

Surmullets (Mullus), 294.

Surnia, 69.

Sus, 374.

Swallow, 65, 104.
Swallow-shrike, 104.
Swan (fossil), 333.

Swift, 66, 104.

Sword-tish, 297.
Sylviade, 65, 88, 94.
Symborodon, 372.
Symplectes, 88.
Synchronism, geological, 227.
Syringopora, 143, 151, 249.
Syrrhaptes, 71.

Tabulate corals, 143, 251.

Tailor-bird, 88, 94.

Talapoin, 397.

Talpa, 847, 348.

Talpavus, 348.

Tamandua, 337.

Tamias, 309, 365.

Tanager, 78.

Tanganyika, Lake, fauna of, 212.

Tantilla, 323.

Tapir (Tapirus), 28, 369.

Tapiravus, 369.

Tapirulus, 369.

Tarsier (Tarsius), 401.

Tarsipes, 100.

Tatouay, 337.

Tattler (fossil), 332.

Tatusia, 337.

Taxidea, 390.

Tectonarchine, 101.

Tciide, 319.

Telegallus, 101.

Telerpeton, 320.

Teleosaurus, 829.

Tellinide, 168, 272.

Temnocyon, 388.

Terebratella, 165, 252, 255.

Terebratula, 148, 165, 188, 207, 252-
255, 260.

Terebratulina, 183, 252, 258, 255, 260.

Tcrebride, 270.

Terrapin, 814.

Tertiary fauna, 11, 171.
Testudo, 314, 315.
Tetragonolepis, 302.
Tetrao, 66.
Tetraogallus, 66.
Teuthide, 268.
Teuthopsis, 138, 166.
Textor, 88.
Textularia, 237.
Thalassarctos, 389.
Thalassemys, 315.
Thalassochelys, 313.

Thamnastreea, 157, 247.

Thaumalia, 66.

Thecidium, 253, 255, 257.

Theeocyathus, 244.

Thecodontosaurus, 160.

Thecosiphonia, 168.
Thecosmilia, 157, 247.
Thelodus, 142, 300.
Theridomys, 363, 364.
Theriodontia, 159.
Theropithecus, 398.
Theropleura, 154.
Theropoda, 162.
Thinohyus, 374.
Thoracosaurus, 329.
Thous, 387.
Thrasaetos, 79.
Thrush, 65, 100, 104.
Thunder-worm, 317.
Thyiacirus, 99.
Thylacoleo, 336.
Tiger, 5, 18, 35, 36.
Timalide, 94, 107.
Tinamide, 78.
Tinamou, 78.
Tinoceras, 367.
Tinoporus, 234.
Tipulide, 283, 284.
Tit, 22, 65, 107.
Titanichthys, 149.

Titanophasma, 150, 282.

Titanotherium, 372.
Toad, 307, 312.

INDEX. 433

Tolypeutes, 338.

Tomistoma, 328.

Tomitherium, 348.

Toothed-carps (Cyprinodonts), 290.

Toucan, 78.

Toxoceras, 168.

Tragoceros, 878.

Tragopan, 66, 95.

Tragulus, 376.

Tree-frog, 307, 309.

Tremarctos, 389.

Triacodon, 348.

Triassic fauna, 156.

Trichecus, 391.

Trichiulus, 151, 286.

Trichodesmium, 120.

Trichoglossus, 101.

Triconodon, 335.

Trigonia, 199.

Trigoniade, 166.

Trigonocephalus, 71.

Trilobites, appearance and disappear-
ance of, 200; distribution of,
275.

Trinucleus, 146, 277.

Trionychide, 314.

Trionyx, 315.

Triton (Amphibia), 306, 307, 312.

Triton (Mollusca), 260.

Tritonide (Mollusca), 169, 270.

Tritylodon, 335.

Trochide, 166.

Trochilus, 78.

Trochoceras, 192.

Trochocyathus, 243, 245.

Trochosmilia, 245.

Troglodytes, 18, 396, 397.

Trogon, 31, 78, 95.

Tropidonotus, 67, 321, 822, 324,
325.

Trout, 290.

Troxites, 283.

Trumpeter, $1.

Trumpet-fish (Centriscus), 295.

Trunk-fish (Ostracion), 303.

454

Trygon, 294, 300.
Tubipora, 148, 247.
Tunicata (pelagic), 120.
Tunny, 297.

Tupaia, 345.

Turaco, 87.

' Turbinolide, 242.
Turbo, 207.

Turbot, 294.

Turdidee, 65.

Turkey, 66; fossil, 332.
Turkey-buzzard, 66.
Turnix, 106.

Turrilites, 168, 267.
Turtle-dove, 102.
Turtles, distribution of, 313.

Type-structure, persistence of, 207.

Typhlopide, 322, 325.

Tyrannus (Tyrannide), 66, 79.
Tyrant-shrike, 66, 79.

Tyrolites, 267.

Tyrrhenian transition region, 195.
Tze-tze, ravages of, 206.

Uintatherium, 367.

Umbra, 288.

Umbrella-bird, 78.

Umbrine, 294.

Uncites, 148.

Ungulata Artiodactyla, 373.
Ungulata Perissodactyla, 368.

Unio (Unionidee), 69, 209, 211, 261.

Upupa, 106.

Uraster, 166.

Urocordylus, 155.

Urodela, distribution of, 306.
Uromys, 100.

Uropeltide, 326.

Urotrichus, 348.

Ursus, 339.

Urus, 379.

Uta, 317.

Vallonia, 265.
Valvata, 69, 209.

INDEX.

Vampyres, 349, 352.
Varanidw, 319.

Velella, 120.

Veneride, 168, 272.
Ventriculites, 168.
Vertigo, 265.
Vesper-mice, 355.
Vespertilio, 349, 351, 354.
Vesperugo, 349, 351, 354.
Vespide, 284.

Vicuna, 375.

Vidua, 88.

Viper (Viperus), 67, 71, 821, 324.
Viscacha, 24, 361.
Viverra, 385.
Viverricula, 385.
Vivipara, 209, 211.

Vole, 356, 365.

Volutide, 270.

Vulture, 66, 88, 100, 106.

Wactail, 66; fossil, 332.
Waldheimia, 255, 257.
Walrus, 391.

Wanderoo, 398.

Wapiti, 381, 382.

Warbler, 65, 88, 94, 100, 104.
Wart-hog, 374.

Wasps, 279, 284.
Water-buck, 84.

Water-mole, 347.

Weasel, 390.

Weaver-bird, 72, 88, 100, 104.
Whales, distribution of, 341.
White-whale, 344.

Whvydah, 88.

Wild-eat, 384.

Wolf, 18, 387.

Wolf-fish (Anarrichas), 293, 294.
Wolverine, 390.

Wombat, 100.

Woodchuck, 359, 365.
Woodpecker, 66, 100; fossil, 332.
Wood- warbler, 66.

Worms (of lakes), 131.

Xenodiscus, 156, 267.

Xenoneura, 146, 282.
Xiphodon, 382.
Xylobius, 151, 286.

Yak, 379.
Yellow-hammer, 70.

Zalophus, 391.
Zamenis, 321.
Zanclodon, 160.

Zaphrentis, 143, 151.

INDEX. 435

Zapus, 358.
Zarachis, 345.
Zebra, 370.

Zebu, 92.
Zeuglodon, 344.
Ziphius, 342, 345.
Zoarees, 294.
Zonites, 150, 208.
Zoological regions, definition of, 56.
Zorilla, 390.
Zygobatis, 300.

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Are, INTELLIGENCE.

By GEORGE J. ROMANES, F.R.S.,

Zoological Secretary of the Isnnzan Society, etc.

12mM0. CxiorH, $1.75.

““My object in the work as a whole is twofold: First. I have thought it de-
sirable that there should be something resembling a text-book of the facts of
Comparative Psychology, to which men of science, and also meta} hysicians, may
turn whenever they have occasion to acquxint themselves with the particuiar
level of intelligence to which this or that species of animal attains. My second
and much more important object is that of cousidering the facts of animal intel-
ligence in their relation to the theory of desceut.”—+srom the Preface.

‘Unless we are greatly mistaken, Mr. Romanes’s work will take its place as
one of the most attractive volumes of the INTERNATIONAL SCIENTIFIC SERIES.
Some persons may. indeed, be disposed to say that it is too attractive, that it
feeds the popular taste for the curious and marvelous without supplying any
commensurate discipline in exact scientific reflection; but the author has, we
think, fully justified himself in his modest preface. The result is the a: pearance
of a collection cf facts which will be a real boon to the student ef Comparative
Psychology, for this is the first attempt to present systematically well-assured
observations on the mental liie of animals.””—Saturday Review.

‘*The author believes himself, not without ample cauxe, to have completely
bridged the sunposed gap between instinct and reason by the authentic proofs
here mar haled of remarkable intelligence in some of the higher animals. It is
the seemingly conclusive evidence of reasonirg powers furnished by the adapta-
tion of means to ends in cases which can not be explained on the theory of inher-
ite] aptitude or habit.’—New York Sun.

“The high standing of the author as an original investigator is a sufficient
guarantee that his task has been conscientiously carried out. His subject is one
of absorbing interest. He has collected and classified an enormous amount of
information concerning the mental attributes of the animal world. The result
is astonishing. We find marvelous intellizence exhibited not only ty animals
which are known to be clever, but by others seemingly without a glimmer of
light, like the snail, for instance. Some animals display imagination, others
affection, and so on. The psychological portion of the discussion is deeply in-
teresting.”—New York Herald.

“The chapter on monkeys closes this excellent work, and perhaps the most
instructive portion of it is that devoted to the life-history of a monkey.”—New
York Times.

“* Mr. Romanes brings to his work a wide information and the best of scientific
methods. He has carefully culled and selected an immense mass of data, choos-
ing with admirable skill those facts which are really significant, and rejecting
those which lacked sustaining evidence or relevancy. The contents of the volume
are arranged with reference to the principles which they seem to him to estab-
lish. The volume is rich and suggestive, and a model in its way.’’— Boston (ourier.

“Tt presents the facts of animal intelligence in relation to the theory of de-
scent, supplementing Darwin and Spencer in tracing the principles which are
concerned in the genesis of mind.”’— Boston ( ommonweailt).

2 en of the most interesting volumes of the series.’—New York Christian at
ork.
_ ‘Few subjects have a greater fascination for the general reader than that
with which this book is occupied.”— Good Literature, New York.

For sale by all booksellers y or sent by mail, post-paid, on receipt of price.

New York: D. APPLETON & CO., 1, 3, and 5 Bond Street.

ACM f E-R OO.) P Jae

By ROBERT HARTMANN,

Professor in the University of Berlin.

With 63 Illustrations = ,Heoiye, Js 12mo, cloth, $1.75.

“The anthropoid, or manlike or tailles3s, apes include the gorilla and chimpanzee
of tropical Africa, the orang of Borneo and Sumatra, and the gibbons of the East
Indies, India, and some other parts of Asia. ‘Ibe author of the present work has
given much attention to the group. Like most living zdlogists he is an evolutionist,
and hoids that man can not have descende:l from any of the fossil species which have
hitherto come under our notice, nor yet from any of the species now extant: it is
more probable that both types have been produced from a common ground-form
which has become extinet.’— Ze Nutzon.

“This Berlin professor is constrained, after a full presentation of the opinions and
arguments of scientists and philosophers, and a careful collection and anulysis of
reeent facts and observation, to declare: * A great chasm between man and anthro-
poids is constituted, as I believe, by te fact that the human race is capaodle of educa-
tion. and is able to acquire the highest mental culture, while the most intelligent
anthropoid can only recvive a certain mechanical training.”—ew ork Observer.

“Tt will be found. by those who follow the anthor’s exegesis with the heed and
candor it deserves, that tie simian ancestry of man does notas yet rest upon such
solid and perfected proofs as to warrant the assumption of absolute certainty in which
materialists indulye.’—New York Sun.

“¢The International Scientific Series’ has now reached its fifty-second volume.
Started as a venture. the result of which was very doubtful, the series has made its
own way into the colleges, academies, and publie and private libraries of the country.
Its secure position is due to the uniform excellence of the works which bear its name,
and to the faith, energy, and capital of D. Appleton & Co. This house knows by long
experience that it pays to publish first-class scientific works. If the tone of such
books sees at first to be too hich for the pubiie taste, then it only reinains to educate
the peogle up to them. ‘This has been successfully done in the case of ‘The inter-
national Scientific Series.’ One of its marked characteristics is the fullness of treat-
ment accorded to every subject in every volume. Thus in the fifty-second issue re-
lating to ‘ Anthropoid Aves,’ the author, Professor Hartmann, of the University of
Berlin. tells everything that one could possibly care to know alout the apes whose
physical structure most nearly resembles that of man. It contains all that is in the
libraries, plus a mass of the author's original observations. The gorilla, chimpanzze,
orang-outang, and gibbon, undergo a minute and profound examination —in wid life,
in captivity. and in the dissectinz-room. There are more than 3.0 pages of this novel
and interesting matter, accompanied by sixty-three illustrations. When the attentive
reader has finished the book he possesses all that science has yet discovered about the
nature and habits of anthropoid apes.’—New York Journal of Commerce.

“The most able and satisfactory summary of our knowledge upon this important
branch of science which has yet appeared.’’— Boston Courier.

“The work is necessarily less complete than Huxley's monograph on ‘ The Craw-
fish.’ or Mivart’s on * The Gat.’ but it is a worthy companion of those brilliant works;
aad in saying this we bestow praise equally high and deserved.”—Boston Gazette.

“The arrangement of the work is most satisfactory. The volume is one of
the most entertaining of the series.”—Hartford Evening Post.

New York: D, APPLETON & CO., 1, 38, & 5 Bond Street.

eee VL ee Vi Aoi | A.

IN, CHER RELATION. £@ PRIMEVAL + TIMES.

Ey Professor OSCAR SCEMIDT,
Author of ‘The Doctrine of Descent and Darwinism.”

With 51 Woodcuts - - - - 28mo. Cloth, $1.50.

‘* Professor Schmidt was one of tle best authorities on the subject which he
hag here treated with the knowledge derived from the studies of 2 litetime. We
use the past tense in sneaking of him, because, since this book was pritted, its
accomplished author has died in the fullness of his powers. Although he pre-

ared it nominally for the use of advanced students, there are few if any pages
in his book which can not be readily understood by the ordinary reader. As
the title implies, Professor Schmidt has traced the iinks of connection between
existing mammalia and those types of which are known to us only through the
disclosures of geology. Pigs, camels, deer, horses, «lephauts. whales. scea's,
and apes, are a few of the clus es whose development, step by step, is thus care-
fully shown.”—Wew York Journal «f Commerce.

“The author undertakes to trace the history of mammalia through all the
stages of their geologico-zodlogical development. It is unnecessary to say that
his line of speculation takes him through many misty labyrinths of thought.
While, however, the writer deals much with intricate hypotheses, he devotes
much space to the anatomical structure and other physical peculiarities of the
mammalia. This phase of his work gives it value apart from his theory.”’—
New York Herald.

““The work is an excellent ana discriminating treatise upon one of the most
important branches of what is by far the most stupencous scientific problems
of the day. It is marked hy ripe scholarship, keen intuition into the value and
relations of facts, and by that clearness which can only result from a perfect
mastery of the subject on the part of the author.’’—Bosion Courier.

‘The author presents this as furnishing ‘ proofs of the necesrity, the truth,
and the value of Darwinism as the foundation for the theory of descent,’ within
the limited field des: ribed by the title. The work is supplemenral to the au-
thor’s treatise on the * Doctrine of Descent and Darwinism,’ pnblished in the
saine series, but it is complete in itself, and includes the results of the lutest
scientitic research in this field..”.— Boston Journal.

* Professor Schmidt offers this work as ‘a senggestive introduction to that
portion of the animal kingdom which stands closest to anthropology.” He com-
pares in detail hving mammalia with their paleontological ancestors, paying
particular attention to the structure of the teeth. Professor Schmidt asserts
that man’s teeth have decreased in number 6uring bis Gevelopment, and are
likely to decr-ase in future. He believes that man will retain his present com-
plement of fingers and toes, but that the race will eventually hecome bald. The
work indicates minuteness of research, and the subject-matter is ably pre-
sented.”— Albany Evenina Journal.

** As presenting the results of a considerab'e amount of original work the
volume should meet with a wide welcome at the hands of students of natural
history as a science of dvvelopment. It does not deal with (what human vanity
has chosen to call) the highest types of the animal kingdom merely as subjects
for description, or even for comparison with other forms, but considers them in
their relations to surrounding facts. This invelves a study of the changes in
organism due to the alteration of thoge conditions through the lapse of geologic
time.”— Chicago Tribune.

“The history of the development of animals and the history of the earth and
geography are made to confirm one another. The book is illustrated with woad-
cuts, which will prove both interesting and instructive. It tells of living mam-
malia, pizs, hippopotami, camels. deer, antelopes. oxen. rhinoceroses, horses,
elephants, sea-cows, whales, dogs, seals, insect-eaters, rodents, bats, semi apes,
apes and their ancestors, and the man of the future.”-— Syracuse (N. Y.) Herald.

New York: D. APPLETON & CO., 1, 3, & 5 Bond Street.

FARTHOUAKES AND OTfhme
EARTH MOVEMENTS.

By JOHN MILNE,

Professor of Mining and Geology in the Imperial College of Engineering, Tokio, Japzn-

With 23 Illustrations. - - - 1£mo, cloth, $1.75.

An attempt is made in this volume to give a systematic account of various
Earth Movements. These comprise Harthquakes, or the sudden violent movye-
ments of the ground ; Harth 7remors, or minute movements which escape our
attention by the smallness of their amplitude ; Harta Pulsations, or movemenis
which are overlooked on account of the length of their period; and Harth Oscilla-
tions. or movements of long period and large amplitude.

* Having chosen Japan as the center of active seismic energies, Mr. Milne has
had the fullest. opportunity of studying earthquakes, and this volume gives a sys-
tematic account of various earth mcvements. Disturbances at sea, magnitude
of waves, velocity of propagation, records of tides gauges, all find their place in
this volume. The many questions of a cosmical character are all ably treated by
Professor Milne. One would have thought that from experience the Japanese
would have built earthquake-proof houses, but Professor Milne says they have
not.’—New York Times. ‘

“Tn this little book Professor Milne has endeavored to bring together al that
is known concerning the nature and causes of earthquake movements. [is task
was one of much difficulty. Professor Milne’s excellent work in the science of
seismolozy has been done in Japan, in a regien of incessant shocks of sufficient
energy to make observation possitle, yet, with rare exceptions, of no disastrous
effects. He has had the good fortune to be aided by Mr. Thomas Gray, a ventle-
man of gre it constructive skill, as well as by Professors J. A. Ewing, W. 8. Chap-
jin, and his other collea*ues in the scientific colony which has gathered about the
Imperial University of Japan. To these gentlemen we owe the best of our sci-
ence of seismolozy, for before their achievements we had nothing of value con-
cerning the physical conditions of earthquakes except the great works of Robert
Mallet; and Mallet, with all his genius and devotion to the subject, had but lew
chances to observe the actual shocks, aud so failed to understand many of their
important features.”"— The Nation.

“This volume contains a sreat deal in the way of results of recent cbservetion
that has never before been given to the reading public. A large part of the ma-
terial used was odtained from experiment and Criginal investigation during an
eight years’ residence in Japan, where the author had an opportunity of obsery-
ing an earthquake on an average of once a week."’—Aew York Christian Union.

‘*The author considers the primary causes of earthquakes to be telluric heats,
solar heat, and variations in gravitating influences, Among the secondary causes
are expansions and contractions of the earth’s crust, variations in temperature,
barometrical pressure, rain, wind, ete. Some are due to explosions of steam
beneath the crust of the earth, others to chemical action forming caverns in the
earth which give way, and still others to volcanic evisceration. The subject in
all its bearings is exhaustively treated in the light of the latest researches. and
affords a very interesting study of a class of natural phenomena which have al-
ways been involved in more or less obscurity,"’— Chicago Evening Journal.

‘** Although it is addressed toa special class of readers, it has an interest which
may be said to be universal. It will surprise readers to be told that nearly two
thousand works have been published on tke particular subject of earthquakes. In
China a commission was appointed more than 1700 years ago to investigate the
causes of these phenomena, and sixty-five works exist in the Japanere languave
devoted to their scientific consideration. The first part of this work deais with
the various movements, oscillations, and tremors of the earth, with their effects;
the later chapters being devoted to the theories of various writers on the phe-
nomena, The volume is well illustrated.”"— Boston Evening Transcript.

New York: D. APPLETON & CO., 1, 3, & 5 Bond Street. ~~

“a

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