_Rodentia._--This order is represented in the Pliocene by a beaver, a

porcupine, and an American mouse (_Hesperomys_), all extinct species of

living genera, the _Hystrix_ being an Old World type; and Professor Cope

has recently described _Panolax_, a new genus of hares from the Pliocene of

New Mexico. The Miocene deposits have furnished an extinct genus allied to

the hares--_Palæolagus_; one of the squirrel family--_Ischyromys_; a small

extinct form of beaver--_Palæocastor_; and an extinct mouse--_Eumys_. The

Eocene strata of Wyoming have lately furnished two extinct forms of

squirrel, _Paramys_ and _Sciuravus_; and another of the Muridæ (or mouse

family), _Mysops_.

_Cetacea._--Numerous remains of dolphins and whales, belonging to no less

than twelve genera, mostly extinct, have been found in the Miocene deposits

of the Atlantic and Gulf States, from New Jersey to South Carolina and

Louisiana; while seven genera of the extinct family, Zeuglodontidæ, have

been found in Miocene and Eocene beds of the same districts. Some remains

associated with these are doubtfully referred to the Seal family (Phocidæ)

among the Carnivora.

_Edentata._--Till quite recently no remains of this order have occurred in

any North American deposits below the Post-Pliocene; but in 1874 Prof.

Marsh described some remains allied to _Megalonyx_ and _Mylodon_, from the

Pliocene beds of California and Idaho, and forming a new genus,

_Morotherium_. As these remains have only occurred to the west of the Rocky

Mountains, and in Pliocene deposits whose exact age is not ascertained,

they hardly affect the remarkable absence of this group from the whole of

the exceedingly rich Tertiary deposits in all other parts of North America.

_General Relations of the extinct Tertiary Mammalia of North America and

Europe._--Having now given a sketch of the extinct Mammalia which inhabited

Europe and North America during the Tertiary period, we are enabled by

comparing them, {141}to ascertain their relations to each other, and to see

how far they elucidate the problem of the birth-place and subsequent

migrations of the several families and genera. We have already pointed out

the remarkable features of the Quaternary (or Post-Pliocene) fauna of North

America, and now proceed to discuss that of the various Tertiary periods,

which is closely connected with the extinct fauna of Europe.

The Tertiary Mammalia of North America at present described belong to from

eighty to one hundred genera, while those of Europe are nearly double that

number; yet only eighteen genera are common to the two faunas, and of these

eight are living and belong chiefly to the Pliocene period. Taking first,

the genera which in America do not go back beyond the Pliocene period (ten

in number), we find that eight of them in Europe go back to the Upper

Miocene. These are _Felis_, _Pseudælurus_, _Hipparion_, _Cervus_,

_Mastodon_, _Elephas_ (in India), _Castor_ and _Hystrix_; while another,

_Canis_, goes back to the Upper Eocene and the tenth, _Equus_, confined to

the newer Pliocene or perhaps to the Post-Pliocene in America, extends back

to the older Pliocene in Europe. Of the seven European genera which are

confined to the Miocene period in America, three, _Hyænodon_,

_Anchitherium_, and _Lophiodon_ go back to the Eocene in Europe; three

others, _Machairodus_, _Rhinoceros_, and _Aceratherium_, are also of

Miocene age in Europe; _Amphicyon_ goes back to the Lower Miocene of

Europe. _Lophiotherium_ belongs to the Eocene of both countries.

If we turn now to families instead of genera, we find that the same general

rule prevails. Mustelidæ (weasels), Ursidæ (bears), true Equidæ (horses),

and Bovidæ (oxen &c.), go no further back in America than the Pliocene,

while they all go back to the Miocene in Europe. Suidæ (swine) and

Anoplotheridæ (extinct) are found in the American Miocene and in the

European Eocene. Anchitheridæ (extinct) reach the Upper Eocene in America,

while in Europe they range through Upper, Middle, and Lower Eocene. Cervidæ

(deer) alone are Miocene in both countries. There remain two families in

which America has the preeminence. Camelidæ (camels) were wonderfully

developed in {142}the American Pliocene and Miocene periods, abounding in

genera and species; whereas in Europe the group only exists in the

Post-Pliocene or Lower Pliocene, with one Upper Miocene species of

_Camelus_ in N. India. The Anthracotheridæ (extinct), found only in the

Upper Miocene of France and India, reach even the Lower Eocene in America.

These facts may be due, in part, to a want of strict co-ordination between

the Tertiary deposits of Europe and North America,--in part to the

imperfection of the record in the latter country. Yet it does not seem

probable that they are altogether due South America and well marked

differences to imperfect knowledge; yet we find such important families as

the Civets, Hyænas, Giraffes, and Hippopotami absent from America, with the

Weasels, and Antelopes almost so; while America possesses almost all the

Camelidæ, two peculiar orders, Dinocerata and Tillodontia, and four

remarkably peculiar families, Limnotheridæ, Lemuravidæ, Oreodontidæ and

Brontotheridæ. If then the facts at present known represent approximately

the real time-relations of the groups in question on the two continents,

they render it probable that weasels, bears, true horses, swine, oxen,

sheep and antelopes, originated on the Old World continent, and were

transmitted to America during some part of the Miocene period; while camels

originated in the New World, and somewhere about the same time passed over

to Europe. Of the extinct families common to the two hemispheres, the

Anthracotheridæ alone seem to have had an American origin. Of the genera

common to the two countries, almost all seem to have had a European origin,

the only genera of equal date being the two rhinoceroses and three

Anchitheridæ; but if the Brontotheridæ are allied to the Rhinocerotidæ,

these latter may have originated in America, although now an exclusively

Old World type. These conclusions are not improbable when we consider the

much greater size of the Old World continents, extending far into the

tropics and probably {143}always more or less united to the tropical areas;

while the evidence of the extinct mammalia themselves shows, that South

America has been for the most part isolated from the northern continent,

and did not take part in the development of its characteristic Tertiary

fauna.

Before speculating further on this subject, it will be well to lay before

our readers a summary of South American palæontology, after which we shall

be in a better position to draw correct inferences from the whole body of

the evidence.

SOUTH AMERICA.

Unfortunately, our knowledge of the interesting fossil fauna of this

continent, is almost wholly confined to the Post-Pliocene and Pliocene

periods. A few remains have been discovered in deposits believed to be of

Eocene age, but nothing whatever representing the vast intervening period,

so rich in peculiar forms of animal life both in North America and Europe.

_Fauna of the Brazilian caves._--What we know of the Post-Pliocene period

is chiefly due to the long-continued researches of Dr. Lund in the caves of

Central Brazil, mostly situated in a district near the head waters of the

San Francisco river in the Province of Minas Geraes. The caves are formed

in limestone rocks, and are so numerous that Dr. Lund visited thousands,

but only sixty contained bones in any quantity. These caves have a floor of

reddish earth, often crowded with bones. In one experiment, half a cubic

foot of this earth contained jaws of 400 opossums, 2,000 mice, besides

remains of bats, porcupines and small birds. In another trial, the whole of

the earth in a cavern was carried out for examination, amounting to 6,552

firkins; and, from a calculation made by measured samples, it was estimated

to contain nearly seven millions of jaw-bones of cavies, opossums,

porcupines, and mice, besides small birds, lizards, and frogs. This immense

accumulation is believed to have been formed from the bodies of animals

brought into the cavern by owls; and, as these are unsocial birds, the

quantity found implies an {144}immense lapse of time, probably some

thousands of years. More than 100 species of Mammalia, in all, were

obtained in these caves. Some were living species or closely allied to

such; but the majority were extinct, and a considerable number, about

one-fourth, belonged to extinct genera, or genera not now inhabiting South

America. Stone implements and human remains were found in several of the

caves with extinct animals. The following enumeration of these remains is

from the corrected list of M. Gervais.

_Primates._--Extinct species of _Cebus_, _Callithrix_, and _Jacchus_--South

American genera of monkeys; with an extinct genus, _Protopithecus_--an

animal of large size but belonging to the American family Cebidæ.

_Chiroptera._--Species belonging to the South American Phyllostomidæ, and

to two South American genera of other families.

_Carnivora._--Five species of _Felis_, some allied to living animals,

others extinct; a species of the widespread extinct genus _Machairodus_;

and a small species referred to _Cynælurus_, the genus containing the

hunting leopard now found only in Africa and India. Canidæ are represented

by _Canis_ and _Icticyon_ (a living Brazilian species of the latter genus),

and the extinct genus _Speothos_. Mustelidæ are represented by extinct

species of the South American genera _Mephitis_ and _Galictis_. Procyonidæ,

by a species of _Nasua_. Ursidæ, by _Arctotherium_, a genus closely

resembling, if not identical with, that containing the "spectacled bear" of

Chili.

_Ungulata._--_Equus_, _Tapirus_, _Dicotyles_, _Auchenia_, _Cervus_,

_Leptotherium_, and _Antilope_, are the cave-genera of this order. _Equus_

and _Antelope_ are particularly interesting, as representing groups forming

no part of existing South American zoology; while the presence also of

_Leptotherium_, an extinct genus of antelopes, shows that the group was

fairly represented in South America at this comparatively recent period.

_Proboscidea._--A species of _Mastodon_, found also in the Pliocene of La

Plata, represents this order.

_Rodentia._--These abound. _Dasyprocta_, _Cælogenys_, _Cavia_, _Kerodon_,

all living genera of Caviidæ, are represented by {145}extinct species.

_Cercolabes_, the 'tree porcupine' (Cercolabidæ) has two species, one as

large as a peccary; _Myopotamus_, _Loncheres_, _Carterodon_, are existing

genera of spiny rats (Echimyidæ); and there are two extinct genera of the

same family, _Lonchophorus_ and _Phyllomys_. _Lagostomus_ (Chinchillidæ),

the viscacha of the Pampas, is represented by an extinct species. There is

also an extinct species of _Lepus_; several species of _Hesperomys_ and

_Oxymycterus_; and a large _Arvicola_, a genus not living in South America.

_Edentata._--These, which constitute the great feature of the existing

South American fauna, were still more abundant and varied in the Cave

period, and it is remarkable that most of them are extinct _genera_. The

armadillos are alone represented by living forms, _Dasypus_, and _Xenurus_;

_Eurydon_ and _Heterodon_, are extinct genera of the same family, as well

as _Chlamydotherium_--huge armadillos the size of a tapir or rhinoceros,

and _Pachytherium_, which was nearly as large. The ant-eaters are

represented only by _Glossotherium_, an extinct form allied to

_Myrmecophaga_ and _Manis_. The sloths were more numerous, being

represented by the extinct genera _Cælodon_, _Sphenodon_ and _Ochotherium_,

the last of large size. The huge terrestrial sloths--Megatheridæ, also

abounded; there being species of _Megatherium_ and _Megalonyx_, as well as

the allied _Scelidotherium_, supposed to have some affinity for the African

_Orycteropus_.

_Marsupials._--No new forms of these appear, but numerous species of

_Didelphys_, all closely allied to opossums still living in South America.

The preceding sketch of the wonderful cave fauna of Central Brazil, is

sufficient to show that it represents, in the main, a period of great

antiquity. Not only are almost the whole of the species extinct, but there

are twenty extinct genera, and three others not now inhabitants of South

America. The fact that so few remains of the living animals of the country

are found in these caves, indicates that some change of physical conditions

has occurred since they were the receptacles of so many of the larger

animals; and the presence of many extinct genera of {146}large size,

especially among the Edentata and American families of Rodents, are

additional proofs of a very high antiquity. Yet many of these cave animals

are closely allied to those which are found in North America in the

Post-Pliocene deposits only, so that we have no reason to suppose the

cave-fauna to be of much earlier date. But the great amount of organic

change it implies, must give us an enlarged idea of the vast periods of

time, as measured by years, which are included in this, the most recent of

all geological epochs.

_Pliocene Period of Temperate South America._--We have now to consider the

numerous remains of extinct animals found in various deposits in the

Pampas, and in Patagonia, and a few in Bolivia. The age of these is

uncertain; but as they are very similar to the cave-fauna, though

containing a somewhat larger proportion of extinct genera and some very

remarkable new forms, they cannot be _very_ much older, and are perhaps

best referred at present to the newer portion of the Pliocene formation.

_Carnivora._--The genus _Machairodus_ or sabre-toothed tigers, represents

the Felidæ. There are several species of wolves (_Canis_); a weasel

(_Mustela_); two bears of the Brazilian cave-genus _Arctotherium_; and the

extinct European genus _Hyænarctos_.

_Ungulata._--There are two species of _Equus_, found in the Pampas, Chili,

and Bolivia; two of _Macrauchenia_, an extraordinary extinct group allied

to the tapir and _Palæotherium_, but with the long neck, and general size

of a camel. A second species found on the highlands of Bolivia is much

smaller.

A more recent discovery, in Patagonia, is the almost perfect series of

teeth of a large animal named _Homalodontotherium_; and which is believed

by Professor Flower, who has described it, to have been allied to

_Rhinoceros_, and still more to the Miocene _Hyracodon_ from North America;

and also to present some resemblances to _Macrauchenia_, and though much

more remotely, to the curious genus _Nesodon_ mentioned further on.

The Artiodactyla, or even-toed Ungulates, are represented by a species of

_Dicotyles_, or peccary, found in the deposits of the {147}Pampas; by

_Auchenia_, or llama, of which three extinct species inhabited Bolivia, in

which country two allied but extinct genera, _Palæolama_ and

_Camelotherium_, have also been found. Three species of deer (_Cervus_),

from the Pampas deposits, complete the list of Pliocene Ungulates.

_Proboscidea._--The cave species of _Mastodon_ is found also in the Pampas

deposits, and another in the Andes of Chili and Bolivia.

_Rodents._--These are not so numerous as in the caves. There are species of

the existing genera, _Kerodon_ and _Cavia_ (Caviidæ); _Lagostomus_

(Chinchillidæ); _Ctenomys_ (Octodontidæ); _Lepus_ (hare); _Hesperomys_ and

_Oxymycterus_ (Muridæ); _Arvicola_, a genus not living in South America;

and an extinct genus, _Cardiodus_. There is also a remarkable extinct form,

_Typotherium_, larger than the capybara, and having affinities to Edentates

and Ungulates. Three species have been found in the Pampas deposits.

_Edentata._--These are as abundant and remarkable as in the cave deposits.

_Scelidotherium_, _Megatherium_, _Megalonyx_, _Glossotherium_ and

_Dasypus_, have already been noticed as from the Brazilian caves. We have

here, in addition, the huge _Mylodon_ allied to the _Megatherium_, and the

allied genera--_Gnathopsis_ and _Lestodon_. We then come to the huge

extinct armadillos, _Glyptodon_ and _Schistopleurum_, the former consisting

of numerous species, some of which were as large as an elephant. Another

genus, _Eutatus_, is allied to the living three-banded armadillos; and a

species of the existing genus _Euphractus_ has been found in Bolivia.

_Toxodontidæ._--There remain a number of huge animals rivalling the

Megatherium in size, and forming the genera _Toxodon_ and _Nesodon_, but

whose position is doubtful. Several species have been found in the deposits

of the Pampas and Patagonia. They are allied at once to Ungulates, Rodents,

Edentates, and the aquatic Sirenia, in so puzzling a manner that it is

impossible to determine to what order they belong, or whether they require

a new order to be formed for their reception. Some are believed to date

back to the Miocene period, and they indicate what strange forms may still

be discovered, should any {148}productive deposits be found in South

America of middle Tertiary age.

_Pliocene Mammalia of the Antilles._--These may be noticed here, as they

are of special interest, proving the connection of the larger West Indian

Islands with the Continent some time in the later Tertiary period. They

consist of remains of two large animals belonging to the South American

Chinchillidæ, found in cave deposits in the island of Anguilla, and forming

two new genera, _Amblyrhiza_ and _Loxomylus_; and remain allied to

_Megalonyx_ from Cuba, which have been named _Megalocnus_ and _Myomorphus_.

_Eocene fauna of South America._--The few remains yet discovered in the

Tertiary deposits of the Pampas which are believed to be of Eocene age, are

exceedingly interesting, because they show us another change in the scenery

of the great drama of life; there being apparently a considerable

resemblance, at this epoch, between South America and Europe. They consist

of a large extinct feline animal, _Eutemnodus_; of _Palæotherium_ and

_Anoplotherium_, the well-known extinct Ungulates of the European

Tertiaries, and which have never been found in North America; and of three

genera of Rodents,--_Theridromys_, allied to _Echimys_, and found also in

the Eocene and Miocene of France; _Megamys_, allied to the living

_Capromys_ of the Antilles, and also to _Palæomys_, an extinct form of the

French Miocene; and a very large animal referred to _Arvicola_, a genus

found also in the Pliocene deposits of South America, and abundant in the

northern hemisphere. No Edentates have been found.

The resemblances of this fauna to that of Europe rather than to any part of

America, are so strong, that they can hardly be accidental. We greatly

want, however, more information on this point, as well as some

corresponding evidences as to the condition of West and South Africa about

the same epoch, before we can venture to speculate on their bearing as

regards the early migrations of organic forms.

_General Remarks on the Extinct Mammalian Fauna of the Old {149}and New

Worlds._--Leaving the more special applications of palæontological evidence

to be made after discussing the relations of the existing fauna of the

several regions, we propose here to indicate briefly, some of the more

general deductions from the evidence which has now been laid before our

readers.

The first, and perhaps the most startling fact brought out by our

systematic review, is the very recent and almost universal change that has

taken place in the character of the fauna, over all the areas we have been

considering; a change which seems to be altogether unprecedented in the

past history of the same countries as revealed by the geological record. In

Europe, in North America, and in South America, we have evidence that a

very similar change occurred about the same time. In all three we find, in

the most recent deposits--cave-earths, peat-bogs, and gravels--the remains

of a whole series of large animals, which have since become wholly extinct

or only survive in far-distant lands. In Europe, the great Irish elk, the

_Machairodus_ and cave-lion, the rhinoceros, hippopotamus, and

elephant;--in North America, equally large felines, horses and tapirs

larger than any now living, a llama as large as a camel, great mastodons

and elephants, and abundance of huge megatheroid animals of almost equal

size;--in South America these same megatheroids in greater variety,

numerous huge armadillos, a mastodon, large horses and tapirs, large

porcupines, two forms of antelope, numerous bears and felines, including a

_Machairodus_, and a large monkey,--have all become extinct since the

deposition of the most recent of the fossil-bearing strata. This is

certainly not a great while ago, geologically; and it is _almost_ certain

that this great organic revolution, implying physical changes of such vast

proportions that they must have been due to causes of adequate intensity

and proportionate range, has taken place since man lived on the earth. This

is proved to have been the case in Europe, and is supported by much

evidence both as regards North and South America.

It is clear that so complete and sudden a change in the higher forms of

life, does not represent the normal state of things. Species and genera

have not, at all times, become so rapidly extinct. The time occupied by the

"Recent period," that is the {150}time _since_ these changes took place is,

geologically, minute. The time of the whole of the Post-Pliocene period, as

measured by the amount of physical and _general_ organic change known to

have taken place, is exceedingly small when compared with the duration of

the Pliocene period, and still smaller, probably, as compared with the

Miocene. Yet during these two periods we meet with no such break in the

continuity of the forms of life, no such radical change in the _character_

of the fauna (though the number of specific and generic changes may be as

great) as we find in passing from the Post-Pliocene to recent times. For

example, in Central Europe numerous hyænas, rhinoceroses, and antelopes,

with the great _Machairodus_, continued from Miocene all through Pliocene

into Post-Pliocene times; while hippopotami and elephants continued to live

through a good part of the Pliocene and Post-Pliocene periods,--and then

all suddenly became extinct or left the country. In North America there has

been more movement of the fauna in all the periods; but we have similar

great felines, horses, mastodons, and elephants, in the Pliocene and

Post-Pliocene periods, while _Rhinoceros_ is common to the Miocene and

Pliocene, and camels range continuously from Miocene, through Pliocene, to

Post-Pliocene times;--when all alike became extinct. Even in South America

the evidence is, as far as it goes, all the same way. We find

_Machairodus_, _Equus_, _Mastodon_, _Megatherium_, _Scelidotherium_,

_Megalonyx_, and numerous gigantic armadillos, alike in the caves and in

the stratified tertiary deposits of the Pampas;--yet all have since passed

away.

It is clear, therefore, that we are now in an altogether exceptional period

of the earth's history. We live in a zoologically impoverished world, from

which all the hugest, and fiercest, and strangest forms have recently

disappeared; and it is, no doubt, a much better world for us now they have

gone. Yet it is surely a marvellous fact, and one that has hardly been

sufficiently dwelt upon, this sudden dying out of so many large mammalia,

not in one place only but over half the land surface of the globe. We

cannot but believe that there must have been some physical cause for this

great change; and it must have been a cause capable of acting almost

simultaneously over large {151}portions of the earth's surface, and one

which, as far as the Tertiary period at least is concerned, was of an

exceptional character. Such a cause exists in the great and recent physical

change known as "the Glacial epoch." We have proof in both Europe and North

America, that just about the time these large animals were disappearing,

all the northern parts of these continents were wrapped in a mantle of ice;

and we have every reason to believe that the presence of this large

quantity of ice (known to have been thousands of feet if not some miles in

thickness) must have acted in various ways to have produced alterations of

level of the ocean as well as vast local floods, which would have combined

with the excessive cold to destroy animal life. There is great difference

of opinion among geologists and physicists as to the extent, nature, and

duration of the Glacial epoch. Some believe it to have prevailed

alternately in the northern and southern hemispheres; others that it was

simultaneous in both. Some think there was a succession of cold periods,

each lasting many thousands of years, but with intercalated warm periods of

equal duration; others deny that there is any evidence of such changes, and

maintain that the Glacial epoch was one continuous period of arctic

conditions in the temperate zones, with some fluctuations perhaps but with

no regular alternations of warm periods. Some believe in a huge ice-cap

covering the whole northern hemisphere from the pole to near 50° north

latitude in the eastern, and 40° in the western hemisphere; while others

impute the observed effects either to glaciers from local centres, or to

floating icebergs of vast size passing over the surface during a period of

submersion.

Without venturing to decide which of these various theories will be

ultimately proved to be correct, we may state, that there is an increasing

belief among geologists in the long duration of this ice-period, and the

vast extent and great thickness attained by the ice-sheet. One of the most

recent, and not the least able, of the writers on this question (Mr. Belt)

shows strong reasons for adopting the view that the ice-period was

simultaneous in both hemispheres; and he calculates that the vast amount of

water abstracted from the ocean and locked up {152}in mountains of ice

around the two poles, would lower the general level of the ocean about

2,000 feet. This would be equivalent to a general elevation of the land to

the same amount, and would thus tend to intensify the cold; and this

elevation may enable us to understand the recent discoveries of signs of

glacial action at moderate elevations in Central America and Brazil, far

within the tropics. At the same time, the weight of ice piled up in the

north would cause the land surface to sink there, perhaps unequally,

according to the varying nature of the interior crust of the earth; and

since the weight has been removed land would rise again, still somewhat

irregularly; and thus the phenomena of raised beds of arctic shells in

temperate latitudes, are explained.

Now, it is evident, that the phenomena we have been considering--of the

recent changes of the mammalian fauna in Europe, North America, South

Temperate America, and the highlands of Brazil--are such as might be

explained by the most extreme views as to the extent and vastness of the

ice-sheet, and especially as to its simultaneous occurrence in the northern

and southern hemispheres; and where two such completely independent sets of

facts are found to combine harmoniously, and supplement each other on a

particular hypothesis, the evidence in favour of that hypothesis is greatly

strengthened. An objection that will occur to zoologists, may here be

noticed. If the Glacial epoch extended over so much of the temperate and

even parts of the tropical zone, and led to the extinction of so many forms

of life even within the tropics, how is it that so much of the purely

tropical fauna of South America has maintained itself, and that there are

still such a vast number of forms, both of mammalia, birds, reptiles, and

insects, that seem organized for an exclusive existence in tropical

forests? Now Mr. Belt's theory, of the subsidence of the ocean to the

extent of about 2,000 feet, supplies an answer to this objection; for we

should thus have a tract of lowland of an average width of some hundreds of

miles, added to the whole east coast of Central and South America. This

tract would, no doubt, become covered with forests as it was slowly formed,

would enjoy a perfectly {153}tropical climate, and would thus afford an

ample area for the continued existence and development of the typical South

American fauna; even had glaciers descended in places so low as what is now

the level of the sea, which, however, there is no reason to believe they

ever did. It is probable too, that this low tract, which all round the Gulf

of Mexico would be of considerable width, offered that passage for

intermigration between North and South America, which led to the sudden

appearance in the former country in Post-Pliocene times, of the huge

Megatheroids from the latter; a migration which took place in opposite

directions as we shall presently show.

_The birth-place and migrations of some mammalian families and genera._--We

have now to consider a few of those cases in which the evidence already at

our command, is sufficiently definite and complete, to enable us to

pronounce with some confidence as to the last movements of several

important groups of mammalia.

_Primates._--The occurrence in North America of numerous forms of

Lemuroidea, forming two extinct families, which are believed by American

palæontologists to present generalized features of both Lemuridæ and

Hapalidæ, while in Europe only Lemurine forms allied to those of Africa

have occurred in deposits of the same age (Eocene), renders it possible

that the Primates may have originated in America, and sent one branch to

South America to form the Hapalidæ and Cebidæ, and another to the Old

World, giving rise to the lemurs and true apes. But the fact that apes of a

high degree of organization occur in the European Miocene, while in the

Eocene, a monkey believed to have relations to the Lemuroids and Cebidæ has

also been discovered, make it more probable that the ancestral forms of

this order originated in the Old World at a still earlier period. The

absence of any early tertiary remains from the tropical parts of the two

hemispheres, renders it impossible to arrive at any definite conclusions as

to the origin of groups which were, no doubt, always best developed in

tropical regions.

_Carnivora._--This is a very ancient and wide-spread group, the families

and genera of which had an extensive range in very {154}early times. The

true bears (_Ursus_) are almost the only important genus that seems to have

recently migrated. In Europe it dates back to the Older Pliocene, while in

North America it is Post-Pliocene only. Bears, therefore, seem to have

passed into America from the Palæarctic region in the latter part of the

Pliocene period. They probably came in on the north-west, and passed down

the Andes into South America, where one isolated species still exists.

_Ungulata._--Horses are very interesting. In Europe they date back under

various forms to the Miocene period, and true _Equus_ to the Older

Pliocene. In North America they are chiefly Pliocene, true _Equus_ being

Post-Pliocene, with perhaps one or two species Newer Pliocene; but numerous

ancestral forms date back to the Miocene and Eocene, giving a more perfect

"pedigree of the horse" than the European forms, and going back to a more

primitive type--_Orohippus_. In South America, _Equus_ is the only genus,

and is Post-Pliocene or at most Newer Pliocene. While, therefore, the

ancient progenitors of the Equidæ were common to North America and Europe,

in Miocene and even Eocene times, true horses appear to have arisen in the

Palæarctic region, to have passed into North America in the latter part of

the Pliocene period, and thence to have spread over all suitable districts

in South America. They were not, however, able to maintain themselves

permanently in their new territory, and all became extinct; while in their

birth-place, the Old World, they continue to exist under several varied

forms.

True tapirs are an Old World group. They go back to the Lower Miocene in

Europe, while in both North and South America they are exclusively

Post-Pliocene. They occur in France down to the Newer Pliocene, and must,

about that time, have entered America. The land connection by which this

and so many other animals passed between the Old and New Worlds in late

Tertiary times, was almost certainly in the North Pacific, south of

Behring's Straits, where, as will be seen by our general map, there is a

large expanse of shallow water, which a moderate elevation would convert

into dry land, in a sufficiently temperate latitude.

{155}The peccary (_Dicotyles_), now a characteristic South American genus,

is a recent immigrant from North America, where it appears to have been

developed from ancestral forms of swine dating back to the Miocene period.

Antelopes are an Old World type, but a few of them appear to have entered

North, and reached South America in late Pliocene times. Camels, strange to

say, are a special North American type, since they abounded in that

continent under various ancient forms in the Miocene period. Towards the

end of that period they appear to have entered eastern Asia, and developed

into the Siberian _Merycotherium_ and the North Indian _Camelus_, while in

the Pliocene age the ancestral llamas entered South America.

_Cervidæ_ are a wide-spread northern type in their generalized form, but

true deer (_Cervus_) are Palæarctic. They abounded in Europe in Miocene

times, but only appear in North and South America in the later Pliocene and

Post-Pliocene periods.

True oxen (_Bovinæ_) seem to be an Oriental type (Miocene), while they

appear in Europe only late in the Pliocene period, and in America are

confined to the Post-Pliocene.

Elephants (_Elephantidæ_) are an Old World type, abounding in the Miocene

period in Europe and India, and first appearing in America in Post-Pliocene

or later Pliocene times. Ancestral forms, doubtfully Proboscidean

(_Dinocerata_), existed in North America in the Eocene period, but these

became extinct without leaving any direct descendants, unless the

_Brontotheridæ_ and rhinoceroses may be so considered.

Marsupials are almost certainly a recent introduction into South and North

America from Asia. They existed in Europe in Eocene and Miocene times, and

presumably over a considerable part of the Old World; but no trace of them

appears in North or South America before the Post-Pliocene period.

_Edentata._--These offer a most curious and difficult problem. In South

America they abound, and were so much more numerous and varied in the

Post-Pliocene and Pliocene, that we may be sure they lived also in the

preceding Miocene period. A few living Edentates are scattered over Africa

and Asia, and {156}they flourished in Europe during the Miocene

age--animals as large (in some species) as a rhinoceros, and most allied to

living African forms. In North America no trace of Edentata has been found

earlier than the Post-Pliocene period, or perhaps the Newer Pliocene on the

west coast. Neither is there any trace of them in South America in the

Eocene formations; but this may well be owing to our very imperfect

knowledge of the forms of that epoch. Their absence from North America is,

however, probably real; and we have to account for their presence in the

Old World and in South America. Their antiquity is no doubt very great, and

the point of divergence of the Old World and South American groups, may

take us back to early Eocene, or even to Pre-Eocene times. The distribution

of land and sea may then have been very different from what it is now; and

to those who would create a continent to account for the migrations of a

beetle, nothing would seem more probable than that a South Atlantic

continent, then united parts of what are now Africa and South America.

There is, however, so much evidence for the general permanence of what are

now the great continents and deep oceans, that Professor Huxley's

supposition of a considerable extension of land round the borders of the

North Pacific Ocean in Mesozoic times, best indicates the probable area in

which the Edentate type originated, and thence spread over much of the Old

World and South America. But while in the latter country it flourished and

increased with little check, in the other great continents it was soon

overcome by the competition of higher forms, only leaving a few small-sized

representatives in Africa and Asia.

{157}CHAPTER VIII.

VARIOUS EXTINCT ANIMALS;--AND ON THE ANTIQUITY OF THE GENERA OF INSECTS AND

LAND MOLLUSCA.

EXTINCT MAMMALIA OF AUSTRALIA.

These have all been obtained from caves and late Tertiary or Post-Tertiary

deposits, and consist of a large number of extinct forms, some of gigantic

size, but all marsupials and allied to the existing fauna. There are

numerous forms of kangaroos, some larger than any living species; and among

these are two genera, _Protemnodon_ and _Sthenurus_, which Professor Garrod

has lately shown to have been allied, not to any Australian forms, but to

the _Dendrolagi_ or tree-kangaroos of New Guinea. We have also remains of

_Thylacinus_ and _Dasyurus_, which now only exist in Tasmania; and extinct

species of _Hypsiprymnus_ and _Phascolomys_, the latter as large as a

tapir. Among the more remarkable extinct genera are _Diprotodon_, a huge

thick-limbed animal allied to the kangaroos, but nearly as large as an

elephant; _Nototherium_, having characters of _Macropus_ and

_Phascolarctos_ combined, and as large as a rhinoceros; and _Thylacoleo_, a

phalanger-like marsupial nearly as large as a lion, and supposed by

Professor Owen to have been of carnivorous habits, though this opinion is

not held by other naturalists.

Here then we find the same phenomena as in the other countries we have

already discussed,--the very recent disappearance of a large number of

peculiar forms, many of them far surpassing in size any that continue to

exist. It hardly seems probable that in this case their disappearance can

have been due to the direct effects of the Glacial epoch, since no very

extensive {158}glaciation could have occurred in a country like Australia;

but if the ocean sank 2,000 feet, the great eastern mountain range might

have given rise to local glaciers. It is, however, almost certain that

during late Tertiary times Australia must have been much more extensive

than it is now. This is necessary to allow of the development of its

peculiar and extensive fauna, especially as we see that that fauna

comprised animals rivalling in bulk those of the great continents. It is

further indicated by the relations with New Guinea, already alluded to, and

by the general character of the various faunas which compose the Australian

region, details of which will be found in the succeeding part of this work.

The lowering of the ocean during the Glacial period would be favourable to

the still further development of the fauna of such a country; and it is to

the unfavourable conditions produced by its subsequent rising--equivalent

to a depression of the land to the amount of two thousand feet--that we

must impute the extinction of so many remarkable groups of animals. It is

not improbable, that the disappearance of the ice and the consequent

(apparent) subsidence of the land, might have been rapid as compared with

the rate at which large animals can become modified to meet new conditions.

Extensive tracts of fertile land might have been submerged, and the

consequent crowding of large numbers of species and individuals on limited

areas would have led to a struggle for existence in which the less adapted

and less easily modifiable, not the physically weaker, would succumb.

There is, however, another cause for the extinction of large rather than

small animals whenever an important change of conditions occurs, which has

been suggested to me by a correspondent,[4] but which has not, I believe,

been adduced by Mr. Darwin or by any other writer on the subject. It is

dependent on the fact, that large animals as compared with small ones are

almost invariably slow breeders, and as they also necessarily exist in much

smaller numbers in a given area, they offer far less materials for

favourable variations than do smaller animals. In such an extreme case as

that of the rabbit and elephant, the {159}young born each year in the world

are probably as some millions to one; and it is very easily conceivable

that in a thousand years the former might, under pressure of rapidly

changing conditions, become modified into a distinct species, while the

latter, not offering enough favourable variations to effect a suitable

adaptation, would become extinct. We must also remember the extreme

specialization of many of the large animals that have become extinct--a

specialization which would necessarily render modification in any new

direction difficult, since the inherited tendency of variation would

probably be to increase the specialization in the same directions which had

heretofore been beneficial. If to these two causes we add the difficulty of

obtaining sufficient food for such large animals, and perhaps the injurious

effects of changes of climate, we shall not find it difficult to understand

how such a vast physical revolution as the Glacial epoch, with its

attendant phenomena of elevations and subsidences, icy winds, and sudden

floods by the bursting of lake barriers, might have led to the total

extinction of a vast number of the most bulky forms of mammalia, while the

less bulky were able to survive, either by greater hardiness of

constitution or by becoming more or less modified. The result is apparent

in the comparatively small or moderate size of the species constituting the

temperate fauna, in all parts of the globe.

It is much to be regretted that no mammalian remains of earlier date have

been found in Australia, as we should then see if it is really the case

that marsupials have always formed its highest type of mammalian life. At

present its fossil fauna is chiefly interesting to the zoologist, but

throws little light on the past relations of this isolated country with

other parts of the globe.

MAMMALIAN REMAINS IN THE SECONDARY FORMATIONS.

In the oldest Tertiary beds of Europe and North America, we have (even with

our present imperfect record) a rich and varied mammalian fauna. As

compared with our living or recent highly specialized forms, it may be said

to consist of generalised types; but as compared with any primeval

mammalian type, it must be pronounced highly specialised. Not only are such

diversified {160}groups as Carnivora, Perrissodactyle and Artiodactyle

Ungulates, Primates, Chiroptera, Rodents, and Marsupials already well

marked, but in many of these there is a differentiation into numerous

families and genera of diverse character. It is impossible therefore to

doubt, that many peculiar forms of mammalia must have lived long anterior

to the Eocene period; but there is unfortunately a great gap in the record

between the Eocene and Cretaceous beds, and these latter being for the most

part marine continue the gap as regards mammals over an enormous lapse of

time. Yet far beyond both these chasms in the Upper Oolitic strata, remains

of small mammalia have been found; again, in the Stonesfield slate, a

member of the Lower Oolite, other forms appear. Then comes the marine Lias

formation with another huge gap; but beyond this again in the Upper Trias,

the oldest of the secondary formations, mammalian teeth have been

discovered in both England and Germany, and these are, as nearly as can be

ascertained, of the same age as the _Dromatherium_ already noticed, from

North America. They have been named _Microlestes_, and show some

resemblance to those of the West Australian _Myrmecobius_. In the Oolitic

strata numerous small jawbones have been found, which have served to

characterise eight genera, all of which are believed to have been

Marsupials, and in some of them a resemblance can be traced to some of the

smaller living Australian species. These, however, are mere indications of

the number of mammalia that must have lived in the secondary period, so

long thought to be exclusively "the age of reptiles;" and the fact that the

few yet found are at all comparable with such specialised forms as still

exist, must convince us, that we shall have to seek far beyond even the

earliest of these remains, for the first appearance of the mammalian type

of vertebrata.

EXTINCT BIRDS.

Compared with those of mammalia, the remains of birds are exceedingly

scarce in Europe and America; and from the wandering habits of so many of

this class, they are of much less value {161}as indications of past changes

in physical geography. A large proportion of the remains belong to aquatic

or wading types, and as these have now often a world-wide range, the

occurrence of extinct forms can have little bearing on our present inquiry.

There are, however, a few interesting cases of extinct land-birds belonging

to groups now quite strangers to the country in which they are found; and

others scarcely less interesting, in which groups now peculiar to certain

areas are shown to have been preceded by allied species or genera of

gigantic size.

_Palæarctic Region and N. India._--In the caves and other Post-Pliocene

deposits of these countries, the remains of birds almost all belong to

genera now inhabiting the same districts. Almost the only exceptions are,

the great auk and the capercailzie, already mentioned as being found in the

Danish mounds; the latter bird, with _Tetrao albus_, in Italian caverns;

and a species of pheasant (_Phasianus_) said to have occurred in the

Post-Pliocene of France, considerably west of the existing range of the

genus in a wild state.

In the preceding Pliocene deposits, but few remains have been found, and

all of existing genera but one, a gallinaceous bird (_Gallus bravardi_)

allied to the domestic fowl and peacock.

The Miocene beds of France and Central Europe have produced many more

remains of birds, but these, too, are mostly of existing European genera,

though there are some notable exceptions. Along with forms

undistinguishable from crows (_Corvus_), shrikes (_Lanius_), wagtails

(_Motacilla_), and woodpeckers (_Picus_), are found remains allied to the

Oriental edible-nest swift (_Collocalia_) and _Trogon_; a parrot resembling

the African genus _Psittacus_; an extinct form _Necrornis_, perhaps allied

to the plantain-eaters (_Musophaga_); _Homalophus_, doubtfully allied to

woodpeckers, and _Limnatornis_ to the hoopoes. The gallinaceous birds are

represented by three species of pheasants, some very close to the

domesticated species; _Palæoperdix_ allied to the partridges; and

_Palæortyx_, small birds allied to the American genus _Ortyx_, but with

larger wings. There are also species of _Pterocles_ allied to living birds,

and a small pigeon. There are numerous living genera of Accipitres; such as

eagle (_Aquila_), {162}kite (_Milvus_), eagle-owl (_Bubo_), and screech-owl

(_Strix_); with the African secretary-bird (_Serpentarius_), and some

extinct forms, as _Palæocercus_, _Palæohierix_ and _Palæetus_.

Aquatic and wading birds were abundant, including numerous rails, bustards,

herons, sandpipers, gulls, divers, and pelicans. There were also many

ducks, some allied to the genus _Dendrocygna_; the Oriental genus of

storks, _Leptoptilus_; _Ibidipodia_, a remarkable form allied to _Ibis_ and

_Ciconia_; _Elornis_, near _Limosa_; _Pelagornis_, a large bird allied to

gannets and pelicans; _Hydrornis_, allied to the ducks and petrels;

_Dolichopterus_, allied to plovers. Perhaps the most interesting of these

extinct birds are, however, the flamingoes, represented by forms hardly

distinguishable from living species, and by one extinct genus _Palælodus_,

which had very long toes, and probably walked on aquatic plants like the

tropical jacanas.

The Miocene beds of North India have furnished few birds; the only one of

geographical interest being an extinct species of ostrich, not very

different from that now inhabiting Arabia.

On the whole, the birds of Europe at this period were very like those now

living, with the addition of a few tropical forms. These latter were,

however, perhaps more numerous and important than they appear to be, as

they belong to inland and forest-haunting types, which would not be so

frequently preserved as the marsh and lake-dwelling species. Taking this

into consideration, the assemblage of Miocene birds accords well with what

we know of the mammalian fauna. We have the same indications of a luxuriant

vegetation and subtropical climate, and the same appearance of Oriental and

especially of African types. _Trogon_ is perhaps the most interesting of

all the forms yet discovered, since it furnishes us with a central point

whence the living trogons of Asia, Africa, and South America might have

diverged.

In the Eocene we find ourselves almost wholly among extinct forms of birds.

The earliest known Passerine bird is here met with, in _Protornis_,

somewhat similar to a lark, found in the Lower Eocene of Switzerland; while

another Passerine form, _Palægithalus_, and one allied to the nuthatch

(_Sitta_), have been {163}discovered in the Upper Eocene of Paris. Picariæ

of equal antiquity are found. _Cryptornis_, from the Paris Eocene, and

_Halcyornis_ from the Lower Eocene of the Isle of Sheppey, were both allied

to kingfishers; while a form allied to _Centropus_ a genus of cuckoos, or,

as Milne-Edwards thinks, to the Madagascar _Leptosomus_, has been found in

the Upper Eocene of France. Several _Accipitres_ of somewhat doubtful

affinities have been found in the same country; while _Lithornis_, from the

Lower Eocene of the Isle of Sheppey, was a small vulturine bird supposed to

be allied to the American group, _Cathartes_. Among the waders, some

extinct forms of plovers have been found, and a genus (_Agnopterus_),

allied to the flamingoes; while there are many swimming birds, such as

pelicans, divers, and several extinct types of doubtful affinities. Most

intersting of all is a portion of a cranium discovered in the Lower Eocene

of Sheppey, and lately pronounced by Professor Owen to belong to a large

Struthious bird, allied to the New Zealand _Dinornis_ and also perhaps to

the ostrich. Another gigantic bird is the _Gastornis_, from the Lower

Eocene of Paris, which was as large as an ostrich, but which is believed to

have been a generalised type, allied to wading and swimming birds as well

as to the Struthiones.

Beyond this epoch we have no remains of birds in European strata till we

come to the wonderful _Archæopteryx_ from the Upper Oolite of Bavaria; a

bird of a totally new type, with a bony tail, longer than the body, each

vertebra of which carried a pair of diverging feathers.

_North America._--A number of bird-remains have lately been found in the

rich Tertiary and Cretaceous deposits of the United States; but here, too,

comparatively few are terrestrial forms. No Passerine bird has yet been

found. The Picariæ are represented by _Uintornis_, an extinct form allied

to woodpeckers, from the Eocene of Wyoming. Species of turkey (_Meleagris_)

occur in the Post-Pliocene and as far back as the Miocene strata, showing

that this interesting type is a true denizen of temperate North America.

The other birds are, _Accipitres_; waders and aquatics of existing genera;

and a number of extinct forms of the two latter orders--such as,

_Aletornis_ an Eocene wader; {164}_Palæotringa_, allied to the sandpipers,

and _Telmatobius_ to the rails, both Cretaceous; with _Graculavus_, allied

to _Graculus_; _Laornis_ allied to the swans; _Hesperornis_ a gigantic

diver; and _Icthyornis_ a very low form, with biconcave vertebra, such as

are only found in fishes and some reptiles--also from Cretaceous deposits.

_South America._--The caverns of Brazil produced thirty-four species of

birds, most of them referable to Brazilian genera, and many to still

existing species. The most interesting were two species of American ostrich

(_Rhea_), one larger than either of the living species; a large

turkey-buzzard (_Cathartes_); a new species of the very isolated South

American genus _Opisthocomus_; and a _Cariama_, or allied new genus.

_Madagascar and the Mascarene Islands._--We have here only evidence of

birds that have become extinct in the historical period or very little

earlier. First we have a group of birds incapable of flight, allied to

pigeons, but forming a separate family, _Dididæ_; and which, so far as we

yet know, inhabited Mauritius, Rodriguez, and probably Bourbon.

_Aphanapteryx_, an extinct genus of rails, inhabited Mauritius; and another

genus, (_Erythromachus_), Rodriguez. A large parrot, said by Prof. Milne

Edwards to be allied to _Ara_ and _Microglossus_, also inhabited Mauritius;

and another allied to _Eclectus_, the island of Rodriguez. None of these

have been found in Madagascar; but a gigantic Struthious bird, _Æpyornis_,

forming a peculiar family distinct both from the ostriches of Africa and

the _Dinornis_ of New Zealand inhabited that island; and there is reason to

believe that this may have lived less than 200 years ago.

_New Zealand._--A number of extinct Struthious birds, forming two families,

_Dinornithidæ_ and _Palapterygidæ_, have been found in New Zealand. Some

were of gigantic size. They seem allied both to the living _Apteryx_ of New

Zealand and the emu of Australia. They are quite recent, and some of them

have probably lived within the last few centuries. Remains of _Dinornis_

have also been found in a Post-Pliocene deposit in Queensland, N. E.

Australia[5]--a very important discovery, as it {165}gives support to the

theory of a great eastward extension of Australia in Tertiary times.

EXTINCT TERTIARY REPTILES.

These will not occupy us long, as no very great number are known, and most

of them belong to a few principal forms of comparatively little

geographical interest.

Tortoises are perhaps the most abundant of the Tertiary reptiles. They are

numerous in the Eocene and Miocene formations both in Europe and North

America. The genera _Emys_ and _Trionyx_ abound in both countries, as well

as in the Miocene of India. Land tortoises occur in the Eocene of North

America and in the Miocene of Europe and India, where the huge

_Colossochelys_, twelve feet long, has been found. In the Pliocene deposits

of Switzerland the living American genus _Chelydra_ has been met with.

These facts, together with the occurrence of a living _species_ in the

Miocene of India, show that this order of reptiles is of great antiquity,

and that most of the genera once had a wider range than now.

Crocodiles, allied to the three forms now characteristic of India, Africa,

and America, have been found in the Eocene of our own country, and several

species of _Crocodilus_ have occurred in beds of the same age in North

America.

Lizards are very ancient, many small terrestrial forms occurring in all the

Tertiary deposits. A species of the genus _Chamæleo_ is recorded from the

Eocene of North America, together with several extinct genera.

Snakes were well developed in the Eocene period, where remains of several

have been found which must have been from twelve to twenty feet long. An

extinct species of true viper has occurred in the Miocene of France, and

one of the Pythonidæ in the Miocene brown coal of Germany.

Batrachia occur but sparingly in a fossil state in the Tertiary deposits.

The most remarkable is the large Salamander (_Andreas_) from the Upper

Miocene of Switzerland, which {166}is allied to the _Menopoma_ living in

North America. Species of frog (_Rana_), and _Palæophryus_ an extinct genus

of toads, have been found in the Miocene deposits of Germany and

Switzerland.

Fresh water fish are almost unknown in the Tertiary deposits of Europe,

although most of the families and some genera of living marine fish are

represented from the Eocene downwards.

ANTIQUITY OF THE GENERA OF INSECTS.

Fossil insects are far too rarely found, to aid us in our determination of

difficult questions of geographical distribution; but in discussing these

questions it will be important to know, whether we are to look upon the

existing generic forms of insects as of great or small antiquity, compared

with the higher vertebrates; and to decide this question the materials at

our command are ample.

The conditions requisite for the preservation of insects in a fossil state

are no doubt very local and peculiar; the result being, that it is only at

long intervals in the geological record that we meet with remains of

insects in a recognisable condition. None appear to have been found in the

Pliocene formation; but in the Upper Miocene of Oeninghen in Switzerland,

associated with the wonderfully rich fossil flora, are found immense

quantities of insects. Prof. Heer examined more than 5,000 specimens

belonging to over 800 species, and many have been found in other localities

in Switzerland; so that more than 1,300 species of Miocene insects have now

been determined. Most of the orders are represented, but the beetles

(Coleoptera) are far the most abundant. Almost all belong to existing

genera, and the majority of these genera now inhabit Europe, only three or

four being exclusively Indian, African, or American.

In the Lower Miocene of Croatia there is another rich deposit of insects,

somewhat more tropical in character, comprising large white-ants and

dragon-flies differently marked from any {167}now inhabiting Europe. A

butterfly is also well preserved, with all the markings of the wings; and

it seems to be a _Junonia_, a tropical genus, though it may be a _Vanessa_,

which is European, but the fossil most resembles Indian species of

_Junonia_.

The Eocene formations seem to have produced no insect remains; but they

occur again in the Upper Cretaceous at Aix-la-Chapelle, where two

butterflies have been found, _Cyllo sepulta_ and _Satyrites Reynesii_, both

belonging to the Satyridæ, and the former to a genus now spread over

Africa, India, and Australia.

A little earlier, in the Wealden formation of our own country, numerous

insects have been found, principally dragon flies (_Libellula_, _Æshna_);

aquatic Hemiptera (_Velia Hydrometra_); crickets, cockroaches, and cicadas,

of familiar types.

Further back in the Upper Oolite of Bavaria--which produced the wonderful

long-tailed bird, _Archæopteryx_--insects of all orders have been found,

including a moth referred to the existing genus _Sphinx_.

In the Lower Oolite of Oxfordshire many fossil beetles have been found

whose affinities are shown by their names:--_Buprestidium_,

_Curculionidium_, _Blapsidium_, _Melolonthidium_, and _Prionidium_; a wing

of a butterfly has also been found, allied to the Brassolidæ now confined

to tropical America, and named _Palæontina oolitica_.

Still more remote are the insects of the Lias of Gloucestershire, yet they

too can be referred to well-known family types--Carabidæ, Melolonthidæ,

Telephoridæ, Elateridæ, and Curculionidæ, among beetles; Gryllidæ and

Blattidæ among Orthoptera; with _Libellula_, _Agrion_, _Æshna_, _Ephemera_,

and some extinct genera. When we consider that almost the only vertebrata

of this period were huge Saurian reptiles like the _Icthyosaurus_,

_Plesiosaurus_, and _Dinosaurus_, with the flying Pterodactyles; and that

the great mass of our existing genera, and even families, of fish and

reptiles had almost certainly not come into existence, we see at once that

types of insect-form are, proportionately, far more ancient. At this remote

epoch we find the chief family types (the _genera_ of the time of Linnæus)

perfectly differentiated {168}and recognisable. It is only when we go

further back still, into the Palæozoic formations, that the insect forms

begin to show that generalization of type which renders it impossible to

classify them in any existing groups. Yet even in the coal formation of

Nova Scotia and Durham, the fossil insects are said by competent

entomologists to be "allied to _Ephemera_," "near _Blatta_," "near

_Phasmidæ_;" and in deposits of the same age at Saarbrück near Trèves, a

well-preserved wing of a grasshopper or locust has been found, as well as a

beetle referred to the Scarabeidæ. More remarkable, however, is the recent

discovery in the carboniferous shales of Belgium, of the clearly-defined

wing of a large moth (_Breyeria borinensis_), closely resembling some of

the Saturniidæ; so that we have now all the chief orders of

Insects--including those supposed to be the most highly developed and the

most recent--well represented at this very remote epoch. Even the oldest

insects, from the Devonian rocks of North America, can mostly be classed as

Neuroptera or Myriapoda, but appear to form new families.

We may consider it, therefore, as proved, that many of the larger and more

important genera of insects date back to the beginning of the Tertiary

period, or perhaps beyond it; but the family types are far older, and must

have been differentiated very early in the Secondary period, while some of

them perhaps go back to Palæozoic times. The great comparative antiquity of

the _genera_ is however the important fact for us, and we shall have

occasion often to refer to it, in endeavouring to ascertain the true

bearing of the facts of insect distribution, as elucidating or invalidating

the conclusions arrived at from a study of the distribution of the higher

animals.

ANTIQUITY OF THE GENERA OF LAND AND FRESH-WATER SHELLS.

The remains of land and fresh-water shells are not much more frequent than

those of insects. Like them, too, their forms are very stable, continuing

unchanged through several geological {169}periods. In the Pliocene and

Miocene formations, most of the shells are very similar to living species,

and some are quite identical. In the Eocene we meet with ordinary forms of

the genera _Helix_, _Clausilia_, _Pupa_, _Bulimus_, _Glandina_,

_Cyclostoma_, _Megalostoma_, _Planorbis_, _Paludina_ and _Limnæa_, some

resembling European species, others more like tropical forms. A British

Eocene species of _Helix_ is still living in Texas; and in the South of

France are found species of the Brazilian sub-genera _Megaspira_ and

_Anastoma_. In the secondary formation no true land shells have been found,

but fresh water shells are tolerably abundant, and almost all are still of

living forms. In the Wealden (Lower Cretaceous) and Purbeck (Upper Oolite)

are found _Unio_, _Melania_, _Paludina_, _Planorbis_, and _Limnæa_; while

the last named genus occurs even in the Lias.

The notion that land shells were really not in existence during the

secondary period is, however, proved to be erroneous by the startling

discovery, in the Palæozoic coal measures of Nova Scotia, of two species of

Helicidæ, both of living genera--_Pupa vetusta_, and _Zonites priscus_.

They have been found in the hollow trunk of a _Sigillaria_, and in great

quantities in a bed full of Stigmarian rootlets. The most minute

examination detects no important differences of form or of microscopic

structure, between these shells and living species of the same genera!

These mollusca were the contemporaries of Labyrinthodonts and strange

Ganoid fishes, which formed almost the whole vertebrate fauna. This

unexpected discovery renders it almost certain, that numbers of other

existing genera, of which we have found no traces, lived with these two

through the whole secondary period; and we are thus obliged to assume as a

probability, that any particular genus has lived through a long succession

of geological ages. In estimating the importance of any peculiarities or

anomalies in the geographical distribution of land shells as compared with

the higher vertebrates, we shall, therefore, have to keep this possible,

and even probable high antiquity, constantly in mind.

We have now concluded our sketch of Tertiary Palæontology as a preparation

for the intelligent study of the Geographical {170}Distribution of Land

Animals; and however imperfectly the task has been performed, the reader

will at all events have been convinced that some such preliminary

investigation is an essential and most important part of our work. So much

of palæontology is at present tentative and conjectural, that in combining

the information derived from numerous writers, many errors of detail must

have been made. The main conclusions have, however, been drawn from as

large a basis of facts as possible; and although fresh discoveries may show

that our views as to the past history of some of the less important genera

or families are erroneous, they can hardly invalidate our results to any

important degree, either as regards the intercommunications between

separate regions in the various geological epochs, or as to the centres

from which some of the more important groups have been dispersed.

PART III.

_ZOOLOGICAL GEOGRAPHY:_

_A REVIEW OF THE CHIEF FORMS OF ANIMAL LIFE IN THE SEVERAL REGIONS AND

SUB-REGIONS, WITH THE INDICATIONS THEY AFFORD OF GEOGRAPHICAL MUTATIONS._

{173}CHAPTER IX.

THE ORDER OF SUCCESSION OF THE REGIONS.--COSMOPOLITAN GROUPS OF

ANIMALS.--TABLES OF DISTRIBUTION.

Having discussed, in our First Part, such general and preliminary matters

as are necessary to a proper comprehension of our subject; and having made

ourselves acquainted, in our Second Part, with the most important results

of Palæontology, we now come to our more immediate subject, which we

propose to treat first under its geographical aspect. Taking each of our

six regions in succession, we shall point out in some detail the chief

zoological features they present, as influenced by climate, vegetation, and

other physical features. We shall then treat each of the sub-regions by

itself, as well as such of the islands or other sub-divisions as present

features of special interest; endeavouring to ascertain their true

relations to each other, and the more important changes of physical

geography that seem necessary to account for their present zoological

condition.

_Order of Succession of the Regions._--We may here explain the reason for

taking the several regions in a different succession from that in which

they appear in the tabular or diagrammatic headings to each family, in the

Fourth, and concluding part of this work. It will have been seen, by our

examination of extinct animals (and it will be made still clearer during

our study of the several regions) that all the chief types of animal life

appear to have originated in the great north temperate or northern

continents; while the southern continents--now represented by {174}South

America, Australia, and South Africa with Madagascar--have been more or

less completely isolated, during long periods, both from the northern

continent and from each other. These latter countries have, however, been

subject to more or less immigration from the north during rare epochs of

approximation to, or partial union with it. In the northern, more

extensive, and probably more ancient land, the process of development has

been more rapid, and has resulted in more varied and higher types; while

the southern lands, for the most part, seem to have produced numerous

diverging modifications of the lower grades of organization, the original

types of which they derived either from the north, or from some of the

ancient continents in Mesozoic or Palæozoic times. Hence those curious

resemblances in the fauna of South America, Australia, and, to a less

extent, Madagascar, which have led to a somewhat general belief that these

distant countries must at one time or other have been united; a belief

which, after a careful examination of all the facts, does not seem to the

author of this work to be well founded. On the other hand, there is the

most satisfactory evidence that each southern region has been more or less

closely united (during the tertiary or later secondary epoch) with the

great northern continents, leading to numerous resemblances and affinities

in their productions.

In endeavouring to present at a glance in the most convenient manner, the

distribution of the families in the several regions and sub-regions, it was

necessary to arrange them, so that those whose relations to each other were

closest should stand side by side; the first and last being those between

which the relations were least numerous and least important. Influenced by

the usual opinions as to the relations between Australia and South America,

the series was at first begun with the Nearctic, and terminated with the

Australian and Neotropical regions; and it was not till the whole of the

vertebrate families had been gone through, and their distribution carefully

studied, that these last two regions were seen to be really wider apart

than any others of the series. It was therefore decided to alter the

arrangement, beginning with the Neotropical, and ending with the Australian

{175}regions; and a careful inspection of the diagrams themselves, taken in

their entirety, will, it is believed, show that this is the most natural

plan, and most truly exhibits the relations of the several regions.

In the portion of our work now commencing, we are not, however, by any

means bound to begin at either end of this series. Each region is studied

by itself, but reference will often have to be made to all the other

regions; and wherever we begin, we must occasionally refer to facts which

will be given further on. As, however, the great northern continents form

the central mass from which the southern regions, as it were, diverge, and

as the Palæarctic region is both more extensive and much better known than

any other, it undoubtedly forms the most convenient starting-point for our

proposed survey of the zoological history of the earth. We thus pass from

the better known to the less known--from Europe to Africa and tropical

Asia, and thence to Australia, completing the series of regions of the

Eastern Hemisphere. Beginning again with the Neotropical region, we pass to

the Nearctic, which has such striking relations with the preceding and with

the Palæarctic region, that it can only be properly understood by constant

reference to both. We thus keep separate the Eastern and Western

hemispheres, which form, from our point of view, the most radical and most

suggestive division of terrestrial faunas; and as we are able to make this

also the dividing point of our two volumes, reference to the work will be

thereby facilitated.

_Cosmopolitan Groups._--Before proceeding to sketch the zoological features

of the several Regions it will be well to notice those family groups which

belong to the earth as a whole, and which are so widely and universally

distributed over it that it will be unnecessary, in some cases, to do more

than refer to them under the separate geographical divisions.

The only absolutely cosmopolitan families of Mammalia are those which are

aerial or marine; and this is one of the striking proofs that their

distribution has been effected by natural causes, and that the permanence

of barriers is one of the chief {176}agencies in the limitation of their

range. Even among the aerial bats, however, only one family--the

Vespertilionidæ--is truly cosmopolitan, the others having a more or less

restricted range. Neither are the Cetacea necessarily cosmopolitan, most of

the families being restricted either to warm or to cold seas; but one

family, the dolphins (Delphinidæ), is truly so. This order however will not

require further notice, as, being exclusively marine the groups do not

enter into any of our terrestrial regions. The only other family of mammals

that may be considered to be cosmopolitan, is the Muridæ (rats and mice);

yet these are not entirely so, since none are known to be truly indigenous

in any part of the Australian region except Australia itself.

In the class of Birds, a number of families are cosmopolites, if we reckon

as such all which are found in each region and sub-region; but several of

these are so abundant in some parts, while they are so sparingly

represented in others, that they cannot fairly be considered so. We shall

confine that term therefore, to such as, there is reason to believe,

inhabit every important sub-division of each region. Such are, among the

Passerine birds the crows (Corvidæ), and swallows (Hirundinidæ); among the

Picariæ the kingfishers (Alcedinidæ); among other Land birds the pigeons

(Columbidæ), grouse and partridges (Tetraonidæ), hawks (Falconidæ), and

owls (Strigidæ); among the Waders the rails (Rallidæ), snipes

(Scolopacidæ), plovers (Charadriadæ), and herons (Ardeidæ); and among the

Swimmers the ducks (Anatidæ), gulls (Laridæ), petrels (Procellariidæ),

pelicans (Pelecanidæ), and grebes (Podicipidæ).

In the class of Reptiles there are few absolutely cosmopolitan families,

owing to the scarcity of members of this group in some insular sub-regions,

such as New Zealand and the Pacific Islands. Those which are most nearly so

are the Colubridæ among snakes, and the Scincidæ among lizards.

There is no cosmopolitan family of Amphibia, the true frogs (Ranidæ) being

the most widely distributed.

Neither is any family of Freshwater Fishes cosmopolitan, the Siluridæ,

which have the widest range, being confined {177}to warm regions, and

becoming very scarce in the temperate zones.

Among the Diurnal and Crepuscular Lepidoptera (butterflies and sphinges)

the following families are cosmopolitan:--Satyridæ, Nymphalidæ, Lycænidæ,

Pieridæ, Papilionidæ, Hesperidæ, Zygænidæ, and Sphingidæ.

Of the Coleoptera almost all, except some of the small and obscure

families, are cosmopolitan.

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

_Tables of Distribution of Families and Genera._--Having been obliged to

construct numerous tables of the distribution of the various groups for the

purposes of the descriptive part of the work, I have thought it well to

append the most important of them, in a convenient form, to the chapter on

each region; as much information will thereby be given, which can only be

obtained from existing works at the cost of great labour. All these tables

are drawn up on a uniform plan, the same generic and family names being

used in each; and all are arranged in the same systematic order, so as to

be readily comparable with each other. This, although it seems a simple and

natural thing to do, has involved a very great amount of labour, because

hardly two authors use the same names or follow the same arrangement. Hence

comparison between them is impossible, till all their work has been picked

to pieces, their synonymy unravelled, their differences accounted for, and

the materials recast; and this has to be done, not for two or three authors

only, but for the majority of those whose works have been consulted on the

zoology of any part of the globe.

Except in the two higher orders--Mammalia and Birds--materials do not exist

for complete tables of the genera brought down to the present time. We have

given therefore, first, a complete table of all the families of Vertebrata

and Diurnal Lepidoptera found in each region, showing the sub-regions in

which they occur, and their range beyond the limits of the region. Families

which are wholly peculiar to the region, or {178}very characteristic and

almost exclusively confined to it, are in _italics_. The number prefixed to

each family corresponds to that of the series of families in the Fourth

Part of this work, so that if further information is required it can be

readily referred to without consulting the index. Names inclosed in

parentheses--( . . . ) thus--indicate families which only just enter a

region from an adjacent one, to which they properly belong. The eye is thus

directed to the more, and the less important families; and a considerable

amount of information as to the general features of the zoology of the

region, is conveyed in the easiest manner.

The tables of genera of Mammalia and Birds, are arranged on a somewhat

different plan. Each genus is given under its Family and Order, and they

follow in the same succession in all the tables. The number of species of

each genus, inhabiting the region, is given as nearly as can be

ascertained; but in many cases this can only be a general approximation.

The distribution of the genera within the region, is then given with some

detail; and, lastly, the range of the genus beyond the region is given in

general terms, the words "Oriental," "Ethiopian," &c., being used for

brevity, to indicate that the genus occurs over a considerable part of such

regions. Genera which are restricted to the region (or which are very

characteristic of it though just transgressing its limits) are given in

_italics_; while those which only just enter the region from another to

which they really belong, are enclosed in parentheses--( . . . ) thus. The

genera are here numbered consecutively, in order that the number of genera

in each family or each order, in the region, may be readily ascertained (by

one process of subtraction), and thus comparisons made with other regions

or with any other area. As the tables of birds would be swelled to an

inconvenient length by the insertion in each region of all the genera of

Waders and Aquatics, most of which have a very wide range and would have to

be repeated in several or all the regions, these have been omitted; but a

list has been given of such of the genera as are peculiar to, or highly

characteristic of each region.

As this is the first time that any such extensive tables of

{179}distribution have been constructed for the whole of the Mammalia and

Birds, they must necessarily contain many errors of detail; but with all

their imperfections it is believed they will prove very useful to

naturalists, to teachers, and to all who take an intelligent interest in

the wider problems of geography and natural history.

{180}CHAPTER X.

THE PALÆARCTIC REGION.

This region is of immense extent, comprising all the temperate portions of

the great eastern continents. It thus extends from the Azores and Canary

Islands on the west to Japan on the east, a distance not far short of half

the circumference of the globe. Yet so great is the zoological unity of

this vast tract, that the majority of the genera of animals in countries so

far removed as Great Britain and Northern Japan are identical. Throughout

its northern half the animal productions of the Palæarctic region are very

uniform, except that the vast elevated desert-regions of Central Asia

possess some characteristic forms; but in its southern portion, we find a

warm district at each extremity with somewhat contrasted features. On the

west we have the rich and luxuriant Mediterranean sub-region, possessing

many peculiar forms of life, as well as a few which are more especially

characteristic of the Ethiopian region. On the east we have the fertile

plains of Northern China and the rich and varied islands of Japan,

possessing a very distinct set of peculiar forms, with others belonging to

the Oriental region, into which this part of the Palæarctic region merges

gradually as we approach the Tropic of Cancer. Thus, the countries roughly

indicated by the names--Northern Europe, the Mediterranean district,

Central and Northern Asia, and China with Japan--have each well-marked

minor characteristics which entitle them to the rank of sub-regions. Their

boundaries are often indefinable; and those here adopted have been fixed

upon to some extent by considerations of convenience, dependent on custom

and on the more or less perfect knowledge we possess of some of the

intervening countries.

[Illustration: PALAEARCTIC REGION]

{181}_Zoological Characteristics of the Palæarctic Region._--The Palæarctic

region has representatives of thirty-five families of mammalia, fifty-five

of birds, twenty-five of reptiles, nine of amphibia, and thirteen of

freshwater fishes. Comparing it with the only other wholly temperate

region, the Nearctic, we find a much greater variety of types of mammalia

and birds. This may be due in part to its greater area, but more, probably,

to its southern boundary being conterminous for an enormous distance with

two tropical regions, the Ethiopean and Oriental; whereas the Nearctic has

a comparatively short southern boundary conterminous with the Neotropical

region only. This is so very important a difference, that it is rather a

matter of surprise that the two north temperate regions should not be more

unequal in the number of their higher vertebrate forms, than they actually

are.

It is also to the interblending of the Palæarctic with the two adjacent

tropical regions, that we must attribute its possession of so few peculiar

family groups. These are only three; two of reptiles, _Trogonophidæ_ and

_Ophiomoridæ_, and one of fishes, _Comephoridæ_. The number of peculiar

genera is, however, considerable, as the following enumeration will show.

_Mammalia._--The monkey of Gibraltar and North Africa, and an allied

species found in Japan, are now considered to belong to the extensive

eastern genus _Macacus_. The former, however, is peculiar in the entire

absence of the tail, and has by many naturalists, been held to form a

distinct genus, _Inuus_, confined to the Palæarctic region.

Of bats there are one or two genera (_Barbastellus_, _Plecotus_) which seem

to be mainly or wholly Palæarctic, but the classification of these animals

is in such an unsettled state that the distribution of the genera is of

little importance.

In the next order, Insectivora, we have almost the entire family of the

Moles confined to the region. _Talpa_ just enters Northern India; and

_Urotrichus_ is common to Japan and {182}North-Western America, but the

remaining genera, six in number, are all exclusively Palæarctic.

Among Carnivora we have _Nyctereutes_, the curious racoon-dog of Japan and

North-Eastern Asia; _Lutronectes_, an otter peculiar to Japan; and the

badger (_Meles_), which ranges over the whole region, and just enters the

Oriental region as far as Hongkong; _Æluropus_, a curious form of the

Himalayan panda, inhabiting the high mountains of Eastern Thibet; and

_Pelagius_, a genus of seals, ranging from the shores of Madeira to the

Black Sea.

The Ungulata, or hoofed animals, are still more productive of forms

peculiar to this region. First we have the Camels, whose native home is the

desert region of Central and Western Asia and Northern Africa, and which,

even in their domesticated condition, are confined almost wholly within the

limits of the Palæarctic region. Of Deer we have six peculiar genera,

_Dama_ and _Capreolus_ found in Europe, with _Elaphodus_, _Lophotragus_,

_Hydropotes_, and _Moschus_, confined to Northern China and Mongolia. The

great family Bovidæ--comprising the oxen, sheep, goats and

antelopes--furnishes no less than seven peculiar Palæarctic genera. These

are _Poephagus_, the yak of Thibet; _Addax_, a well-known antelope of

Northern Africa and Syria; _Procapra_, _Pantholops_ and _Budorcas_,

antelopine genera peculiar to Thibet and Mongolia; with _Rupicapra_ (the

chamois), and the extraordinary large-nosed antelope _Saiga_, confined to

Europe and Western Asia. Besides these we have _Capra_ (the wild sheep and

goats), all the numerous species of which, except two, are exclusively

Palæarctic.

Coming to the Rodents, we have again many peculiar forms. Of Muridæ (the

mouse and rat tribe), we have six peculiar genera, the more important being

_Cricetus_, _Rhombomys Sminthus_, and _Myospalax_. Of Spalacidæ (mole-rats)

both the Palæarctic genera, _Ellobius_ and _Spalax_, are peculiar.

_Ctenodactylus_, a genus of the South American family Octodontidæ, is found

only in North Africa. To these we may add _Myoxus_ (the dormice) and

_Lagomys_ (the pikas or tail-less hares) as essentially Palæarctic, since

but one species of each genus is found beyond the limits of the region.

_Birds._--It appears to have been the opinion of many {183}naturalists that

the Palæarctic region could not be well characterised by its peculiar

genera of birds. In Mr. Sclater's celebrated paper already referred to, he

remarks, "It cannot be denied that the ornithology of the Palæarctic region

is more easily characterised by what it has not than by what it has," and

this has been quite recently quoted by Mr. Allen, in his essay on the

distribution of North American birds, as if it represented our present

knowledge of the subject. But, thanks to the labours of Dr. Jerdon, Mr.

Swinhoe, Père David and others, we have now learnt that a large number of

birds included in the Indian list, are either mere winter emigrants from

Central Asia, or only inhabit the higher ranges of the Himalayas, and thus

really belong to the Palæarctic region. The result is, that a host of

genera are now seen to be either exclusively or characteristically

Palæarctic, and we have no further difficulty in giving positive

ornithological characters to the region. In the tables appended to this

chapter, all these truly Palæarctic genera will be found printed in

_italics_, with an indication of their distribution, which will sometimes

be found more fully given under the respective families in the fourth part

of this work. Referring to this table for details we shall here summarise

the results.

Of the Sylviidæ or warblers, no less than fourteen genera are either

exclusively or characteristically Palæarctic, of which _Locustella_,

_Sylvia_, _Curruca_ and _Erithacus_ are good examples. Of the oriental

family Timaliidæ, the genus _Pterorhinus_ is Palæarctic. Of Panuridæ, or

reedlings, there are four peculiar genera (comprising almost the whole

family); of Certhiidæ, or creepers, one--_Tichodroma_--which extends

southward to the Abyssinian highlands. Of Paridæ, or tits, one--_Acredula_;

of Corvidæ, or crows, four--_Pica_ (containing our magpie) being a good

example; of Fringillidæ, or finches and buntings, twelve, among which

_Acanthis_, _Pyrrhula_ and _Emberiza_ are good illustrations; of Alaudidæ,

or larks, there are two peculiar genera. Leaving the Passeres we next come

to peculiar forms among the gallinaceous birds: _Syrrhaptes_ among the

Pteroclidæ or sand grouse; four genera of Tetraonidæ or grouse and

partridges, and five of Phasianidæ or pheasants, comprising some of the

most magnificent birds in the world. Lastly {184}among the far-wandering

aquatic birds we have no less than five genera which are more especially

Palæarctic,--_Ortygometra_, the corn-crake, and _Otis_, the great bustard,

being typical examples. We may add to these, several genera almost confined

to this region, such as _Garrulus_ (jays), _Fringilla_ (true finches),

_Yunx_ (wrynecks) and some others; so that in proportion to its total

generic forms a very large number are found to be peculiar or

characteristic.

This view, of the high degree of speciality of the Palæarctic region, will

no doubt be objected to by some naturalists, on the ground that many of the

genera reckoned as exclusively Palæarctic are not so, but extend more or

less into other regions. It is well, therefore, to consider what principles

should guide us in a matter of this kind, especially as we shall have to

apply the same rules to each of the other regions. We may remark first,

that the limits of the regions themselves are, when not formed by the

ocean, somewhat arbitrary, depending on the average distribution of a

number of characteristic forms; and that slight local peculiarities of

soil, elevation, or climate, may cause the species of one region to

penetrate more or less deeply into another. The land boundary between two

regions will be, not a defined line but a neutral territory of greater or

less width, within which the forms of both regions will intermingle; and

this neutral territory itself will merge imperceptibly into both regions.

So long therefore as a species or genus does not permanently reside

considerably beyond the possible limits of this neutral territory, we

should not claim it as an inhabitant of the adjacent region. A

consideration of perhaps more importance arises, from the varying extent of

the range of a genus, over the area occupied by the region. Some genera are

represented by single species existing only in a very limited area; others

by numerous species which occupy, entirely or very nearly, the whole extent

of the region; and there is every intermediate grade between these

extremes. Now, the small localised genera, are always reckoned as among the

best examples of types peculiar to a region; while the more wide-spread

groups are often denied that character if they extend a little beyond

{185}the supposed regional limits, or send one or two, out of a large

number of species, into adjacent regions; yet there is some reason to

believe that the latter are really more important as characterising a

zoological region than the former. In the case of a single isolated species

or genus we have a dying-out group; and we have so many cases of

discontinuous species of such groups (of which _Urotrichus_ in Japan and

British Columbia, _Eupetes_ in Sumatra and New Guinea are examples), that

it is quite as probable as not, that any such isolated species has only

become peculiar to the region by the recent extinction of an allied form or

forms in some other region. On the other hand, a genus consisting of

numerous species ranging over an entire region or the greater part of one,

is a dominant group, which has most likely been for some time extending its

range, and whose origin dates back to a remote period. The slight extension

of such a group beyond the limits of the region to which it mainly belongs,

is probably a recent phenomenon, and in that case cannot be held in any

degree to detract from its value as one of the peculiar forms of that

region.

The most numerous examples of this class, are those birds of the temperate

regions which in winter migrate, either wholly or partially, into adjacent

warmer countries. This migration most likely began subsequent to the

Miocene period, during that gradual refrigeration of the temperate zones

which culminated in the glacial epoch, and which still continues in a

mitigated form. Most of the genera, and many even of the species of birds

which migrate southwards in winter, have therefore, most likely, always

been inhabitants of our present Palæarctic and Nearctic regions; permanent

residents during warm epochs, but only able now to maintain their existence

by migration in winter. Such groups belong truly to the temperate zones,

and the test of this is the fact of their not having any, or very few,

representatives, which are permanent residents in the adjacent tropical

regions. When there are such representative species, we do not claim them

as peculiar to the Northern regions. Bearing in mind these various

considerations, it will be found that we have been very moderate in our

estimate of the number of genera {186}that may fairly be considered as

exclusively or characteristically Palæarctic.

_Reptiles and Amphibia._--The Palæarctic region possesses, in proportion to

its limited reptilian fauna, a full proportion of peculiar types. We have

for instance two genera of snakes, _Rhinechis_ and _Halys_; seven of

lizards, _Trigonophis_, _Psammodromus_, _Hyalosaurus_, _Scincus_,

_Ophiomorus_, _Megalochilus_, and _Phrynocephalus_; eight of tailed

batrachians, _Proteus_, _Salamandra_, _Seiranota_, _Chioglossa_,

_Hynobius_, _Onychodactylus_, _Geotriton_, and _Sieboldia_; and eight of

tail-less batrachians, _Bombinator_, _Pelobates_, _Didocus_, _Alytes_,

_Pelodytes_, _Discoglossus_, _Laprissa_, and _Latonia_. The distribution of

these and other Palæarctic genera will be found in our second vol. chap.

xix.

_Freshwater Fish._--About twenty genera of freshwater fishes are wholly

confined to this region, and constitute a feature which ought not to be

overlooked in estimating its claim to the rank of a separate primary

division of the earth. They belong to the following families:--Percidæ

(three genera), _Acerina_, _Percarina_, _Aspro_; Comephoridæ (one genus),

_Comephorus_, found only in Lake Baikal; Salmonidæ (three genera),

_Brachymystax_, _Luciotrutta_, and _Plecoglossus_; Cyprinodontidæ (one

genus), _Tellia_, found only in Alpine pools on the Atlas Mountains;

Cyprinidæ (thirteen genera), _Cyprinus_, _Carassus_, _Paraphoxinus_,

_Tinca_, _Achilognathus_, _Rhodeus_, _Chondrostoma_, _Pseudoperilampus_,

_Ochetebius_, _Aspius_, _Alburnus_, _Misgurnus_, and _Nemachilus_.

_Summary of Palæarctic Vertebrata._--Summarising these details, we find

that the Palæarctic region possesses thirty-five peculiar genera of

mammalia, fifty-seven of birds, nine of reptiles, sixteen of amphibia, and

twenty-one of freshwater fishes; or a total of 138 peculiar generic types

of vertebrata. Of these, 87 are mammalia and land-birds out of a total of

274 genera of these groups; or rather less than one-third peculiar, a

number which will serve usefully to compare with the results obtained in

other regions.

In our chapter on Zoological Regions we have already pointed out the main

features which distinguish the Palæarctic from the Oriental and Ethiopian

regions. The details now given will {187}strengthen our view of their

radical distinctness, by showing to how considerable an extent the former

is inhabited by peculiar, and often very remarkable generic types.

_Insects: Lepidoptera._--The Diurnal Lepidoptera, or butterflies, are not

very abundant in species, their number being probably somewhat over 500,

and these belong to not more than fifty genera. But no less than fifteen of

these genera are wholly confined to the region. Nine of the families are

represented, as follows:--1. _Danaidæ_; having only a single species in

South Europe. 2. _Satyridæ_; well represented, there being more than 100

species in Europe, and three peculiar genera. 3. _Nymphalidæ_; rather

poorly represented, Europe having only about sixty species, but there is

one peculiar genus. 4. _Libytheidæ_; a very small family, represented by a

single species occurring in South Europe. 5. _Nemeobiidæ_; a rather small

family, also having only one species in Europe, but which constitutes a

peculiar genera. 6. _Lycænidæ_; an extensive family, fairly represented,

having about eighty European species; there are two peculiar genera in the

Palæarctic region. 7. _Pieridæ_; rather poorly represented with thirty-two

European species; two of the genera are, however, peculiar. 8.

_Papilionidæ_; very poorly represented in Europe with only twelve species,

but there are many more in Siberia and Japan. No less than five of the

small number of genera in this family are wholly confined to the region, a

fact of much importance, and which to a great extent redeems the character

of the Palæarctic region as regard this order of insects. Their names are

_Mesapia_, _Hypermnestra_, _Doritis_, _Sericinus_, and _Thais_; and besides

these we have _Parnassius_--the "Apollo" butterflies--highly

characteristic, and only found elsewhere in the mountains of the Nearctic

region. 9. _Hesperidæ_; poorly represented with about thirty European

species, and one peculiar genus.

Four families of _Sphingina_ occur in the Palæarctic region, and there are

several peculiar genera.

In the _Zygænidæ_ there are two exclusively European genera, and the

extensive genus _Zygæna_ is itself mainly Palæarctic. The small family

_Stygiidæ_ has two out of its three genera {188}confined to the Palæarctic

region. In the _Ægeriidæ_ the genus _Ægeria_ is mainly Palæarctic. The

_Sphingidæ_ have a wider general range, and none of the larger genera are

peculiar to any one region.

_Coleoptera._--The Palæarctic region is the richest portion of the globe in

the great family of _Carabidæ_, or predacious ground-beetles, about 50 of

the genera being confined to it, while many others, including the

magnificent genus _Carabus_, have here their highest development. While

several of the smaller genera are confined to the eastern or western

sub-regions, most of the larger ones extend over the whole area, and give

it an unmistakable aspect; while in passing from east to west or

_vice-versâ_, allied species and genera replace each other with

considerable regularity, except in the extreme south-east, where, in China

and Japan, some Oriental forms appear, as do a few Ethiopian types in the

south-west.

Cicindelidæ, or tiger-beetles, are but poorly represented by about 70

species of the genus _Cicindela_, and a single _Tetracha_ in South Europe.

Lucanidæ, or stag-beetles, are also poor, there being representatives of 8

genera. One of these, _Æsalus_ (a single species), is peculiar to South

Europe, and two others, _Cladognathus_ and _Cyclopthalmus_, are only

represented in Japan, China, and Thibet.

Cetoniidæ, or rose-chafers, are represented by 13 genera, two of which are

peculiar to South Europe (_Tropinota_ and _Heterocnemis_), while

_Stalagmosoma_, ranging from Persia to Nubia, and the fine

_Dicranocephalus_ inhabiting North China, Corea, and Nipal, may also be

considered to belong to it. The genera _Trichius_, _Gnorimus_, and

_Osmoderma_ are confined to the two north temperate regions.

Buprestidæ, or metallic beetles, are rather abundant in the warmer parts of

the region, 27 genera being represented, nine of which are peculiar. By far

the larger portion of these are confined to the Mediterranean sub-region. A

considerable number also inhabit Japan and China.

The Longicorns, or long-horned beetles, are represented by no less than 196

genera, 51 of which are peculiar. They are {189}much more abundant in the

southern than the northern half of the region. Several Oriental genera

extend to Japan and North China, and a few Ethiopian genera to North

Africa. Thirteen genera are confined, to the two north temperate regions.

Several large genera, such as _Dorcadion_ (154 species), _Phytæcia_ (85

species), _Pogonochærus_ (22 species), _Agapanthia_ (22 species), and

_Vesperus_ (7 species), are altogether peculiar to the Palæarctic region;

and with a preponderance of _Leptura_, _Grammoptera_, _Stenocorus_, and

several others, strongly characterise it as distinct from the Nearctic and

Oriental regions.

The other families which are well developed in the Palæarctic regions, are,

the Staphylinidæ or rove-beetles, Silphidæ or burying-beetles, Histeridæ or

mimic-beetles, Nitidulidæ, Aphodiidæ, Copridæ (especially in South Europe),

Geotrupidæ or dung-beetles, Melolonthidæ or chafers, Elateridæ or

click-beetles, the various families of Malacoderms and Heteromera,

especially Pimeliidæ in the Mediterranean sub-region, Curculionidæ or

weevils, the Phytophaga or leaf-eaters, and Cocinellidæ or lady-birds.

The number of species of Coleoptera in the western part of the Palæarctic

region is about 15,000, and there are probably not more than 2,000 to add

to this number from Siberia, Japan, and North China; but were these

countries as well explored as Europe, we may expect that they would add at

least 5,000 to the number above given, raising the Palæarctic Coleopterous

fauna to 20,000 species. As the total number of species at present known to

exist in collections is estimated (and perhaps somewhat over-estimated) at

70,000 species, we may be sure that were the whole earth as thoroughly

investigated as Europe, the number would be at least doubled, since we

cannot suppose that Europe, with the Mediterranean basin, can contain more

than one-fifth of the whole of the Coleoptera of the globe.

Of the other orders of insects we here say nothing, because in their case

much more than in that of the Coleoptera and Lepidoptera, is the

disproportion enormous between our knowledge of the European fauna and that

of almost all the rest of the globe. {190}They are, therefore, at present

of comparatively little use for purposes of geographical distribution, even

were it advisable to enter into the subject in a work which will, perhaps,

be too much overburdened with details only of interest to specialists.

_Land Shells._--These are very numerous in the warmer parts of the region,

but comparatively scarce towards the North. South Europe alone possesses

over 600 species, whereas there are only 200 in all Northern Europe and

Asia. The total number of species in the whole region is probably about

1,250, of which the great majority are Helicidæ; the Operculated families

being very poorly represented. Several small genera or sub-genera are

peculiar to the region, as _Testacella_ (West Europe and Canaries);

_Leucochroa_ (Mediterranean district); _Acicula_ (Europe); _Craspedopoma_

(Atlantic Islands); _Leonia_ (Algeria and Spain); _Pomatias_ (Europe and

Canaries); _Cecina_ (Mongolia). The largest genera are _Helix_ and

_Clausilia_, which together comprise more than half the species; _Pupa_,

very numerous; _Bulimus_ and _Achatina_ in moderate numbers, and all the

rest small. _Helix_ is the only genus which contains large and handsome

species; _Bulimus_ and _Achatina_, so magnificent in tropical countries,

being here represented by small and obscure forms only. _Daudebardia_ is

confined to Central and South Europe and New Zealand; _Glandina_ is chiefly

South American; _Hyalina_ is only American and European; _Buliminus_ ranges

over all the world except America; and the other European genera of

Helicidæ are widely distributed. Of the Operculata, _Cyclotus_,

_Cyclophorus_, and _Pupina_ extend from the Oriental region into Japan and

North China; _Tudoria_ is found in Algeria and the West Indies; _Hydrocena_

is widely scattered, and occurs in South Europe and Japan. The genera of

freshwater shells are all widely distributed.

THE PALÆARCTIC SUB-REGIONS.

The four sub-regions which are here adopted, have been fixed upon as those

which are, in the present state of our knowledge, at once the most natural

and the only practicable ones. {191}No doubt all of them could be

advantageously again subdivided, in a detailed study of the geographical

distribution of _species_. But in a general work, which aims at treating

all parts of the world with equal fulness, and which therefore is confined

almost wholly to the distribution of families and genera, such further

subdivision would be out of place. It is even difficult, in some of the

classes of animals, to find peculiar or even characteristic genera for the

present sub-regions; but they all have well marked climatic and physical

differences, and this leads to an assemblage of species and of groups which

are sufficiently distinctive.

_I. Central and Northern Europe._

This sub-region, which may perhaps be termed the "European," is

zoologically and botanically the best known on the globe. It can be pretty

accurately defined, as bounded on the south by the Pyrenees, the Alps, the

Balkans, the Black Sea, and the Caucasus range; and by the Ural Mountains,

or perhaps more correctly the valley of the Irtish and Caspian Sea, on the

east; while Ireland and Iceland are its furthest outliers in the west. To

the north, it merges so gradually into the Arctic zone that no demarcation

is possible. The great extent to which this sub-region is interpenetrated

by the sea, and the prevalence of westerly winds bringing warmth and

moisture from an ocean influenced by the gulf-stream, give it a climate for

the most part genial, and free from extremes of heat and cold. It is thus

broadly distinguished from Siberia and Northern Asia generally, where a

more extreme and rigorous climate prevails.

The whole of this sub-region is well watered, being penetrated by rivers in

every direction; and it consists mainly of plains and undulating country of

moderate elevation, the chief mountain ranges being those of Scandinavia in

the north-west, and the extensive alpine system of Central Europe. But

these are both of moderate height, and a very small portion of their

surface is occupied either by permanent snow-fields, or by barren uplands

inimical to vegetable and animal life. It is, in {192}fact, to these, and

the numerous lesser mountains and hills which everywhere diversify the

surface of Europe, that the variety and abundance of its animal life is

greatly due. They afford the perennial supplies to rivers, and furnish in

their valleys and ever varying slopes, stations suited to every form of

existence. A considerable area of Central Europe is occupied by uplands of

moderate elevation, a comparatively small portion being flat and marshy

plains.

Most of the northern and much of the central portions of Europe are covered

with vast forests of coniferous trees; and these, occupying as they do

those tracts where the winter is most severe, supply food and shelter to

many animals who could not otherwise maintain their existence. It is

probable that the original condition of the greater part, if not the whole,

of temperate Europe, except the flat marshes of the river valleys and the

sandy downs of the coast, was that of woodland and forest, mostly of

deciduous trees, but with a plentiful admixture of such hardy evergreens as

holly, ivy, privet, and yew. A sufficient proportion of these primeval

woods, and of artificial plantations which have replaced them, fortunately

remain, to preserve for us most of the interesting forms of life, which

were developed before man had so greatly modified the surface of the earth,

and so nearly exterminated many of its original tenants. Almost exactly in

proportion to the amount of woodland that still remains in any part of

Europe, do we find (other things being equal) the abundance and variety of

wild animals; a pretty clear indication that the original condition of the

country was essentially that of a forest, a condition which only now exists

in the thinly inhabited regions of the north.

Although the sub-region we are considering is, for its extent and latitude,

richly peopled with animal life, the number of genera altogether peculiar

to it is not great. There are, however, several which are very

characteristic, and many species, both of the smaller mammalia and of

birds, are wholly restricted to it.

_Mammalia._--The genera wholly confined to this sub-region are {193}only

two. _Myogale_, the desman, is a curious long-snouted Insectivorous animal

somewhat resembling the water-rat in its habits. There are two species, one

found only on the banks of streams in the French Pyrenees, the other on the

great rivers of Southern Russia. The other peculiar genus, _Rupicapra_ (the

chamois of the Alps), is found on all the high mountains of Central Europe.

Almost peculiar are _Spalax_ (the mole-rat) found only in Eastern Europe

and Western Siberia; and _Saiga_, an extraordinary large-nosed antelope

which has a nearly similar distribution. Highly characteristic forms, which

inhabit nearly every part of the sub-region, are, _Talpa_ (the mole),

_Erinaceus_, (the hedgehog), _Sorex_ (the shrew), _Meles_ (the badger),

_Ursus_ (the bear), _Canis_ (the wolf and fox), _Mustela_ (the weasel),

_Lutra_ (the otter), _Arvicola_ (the vole), _Myoxus_ (the dormouse), and

_Lepus_ (the hare and rabbit); while _Bos_ (the wild bull) was, until

exterminated by man, no doubt equally characteristic. Other genera

inhabiting the sub-region will be found in the list given at the end of

this chapter.

_Birds._--It is difficult to name the birds that are most characteristic of

this sub-region, because so many of the most familiar and abundant are

emigrants from the south, and belong to groups that have a different range.

There is perhaps not a single genus wholly confined to it, and very few

that have not equal claims to be placed elsewhere. Among the more

characteristic we may name _Turdus_ (the thrushes), _Sylvia_ (the

warblers), _Panurus_ (the reedling), _Parus_ (the tits), _Anthus_ (the

pipits), _Motacilla_ (the wagtails), which are perhaps more abundant here

than in any other part of the world, _Emberiza_ (the buntings),

_Plectrophanes_ (the snow buntings), _Passer_ (the house sparrows), _Loxia_

(the crossbills), _Linota_ (the linnets), _Pica_ (the magpies), _Tetrao_

(grouse), _Lagopus_ (ptarmigan) and many others.

I am indebted to Mr. H. E. Dresser, who is personally acquainted with the

ornithology of much of the North of Europe, for some valuable notes on the

northern range of many European birds. Those which are characteristic of

the extreme Arctic zone, extending beyond 70° north latitude, and tolerably

abundant, are two falcons (_Falco gyrfalco_ and _F. peregrinus_); {194}the

rough-legged buzzard (_Archibuteo lagopus_); the snowy owl (_Nyctea

scandiaca_); the raven (_Corvus corax_); three buntings (_Emberiza

schæniculus_, _Plectrophanes nivalis_ and _P. calcarata_); a lark

(_Otocorys alpestris_); several pipits, the most northern being _Anthus

cervinus_; a wagtail (_Budytes cinereocapilla_); a dipper (_Cinclus

melanogaster_); a warbler (_Cyanecula suecica_); the wheatear (_Saxicola

oenanthe_); and two ptarmigans (_Lagopus albus_ and _L. salicetus_). Most

of these birds are, of course, only summer visitors to the Arctic regions,

the only species noted as a permanent resident in East Finmark (north of

latitude 70°) being the snow-bunting (_Plectrophanes nivalis_).

The birds that are characteristic of the zone of pine forests, or from

about 61° to 70° north latitude, are very numerous, and it will be

sufficient to note the genera and the number of species (where more than

one) to give an idea of the ornithology of this part of Europe. The birds

of prey are, _Falco_ (three species), _Astur_ (two species), _Buteo_,

_Pandion_, _Surnia_, _Bubo_, _Syrnium_, _Asio_, _Nyctala_. The chief

Passerine birds are, _Corvus_ (two species), _Pica_, _Garrulus_ (two

species), _Nucifraga_, _Bombycilla_, _Hirundo_ (two species), _Muscicapa_

(two species), _Lanius_, _Sturnus_, _Passer_ (two species), _Pyrrhula_,

_Carpodacus_, _Loxia_ (two species), _Pinicola_, _Fringilla_ (eight

species), _Emberiza_ (five species), _Alauda_, _Anthus_, _Turdus_ (five

species), _Ruticilla_, _Pratincola_, _Accentor_, _Sylvia_ (four species),

_Hypolais_, _Regulus_, _Phylloscopus_ (two species), _Acrocephalus_,

_Troglodytes_, and _Parus_ (six species). Woodpeckers are abundant, _Picus_

(four species), _Gecinus_, and _Yunx_. The kingfisher (_Alcedo_),

goatsucker (_Caprimulgus_), and swift (_Cypselus_) are also common. The

wood-pigeon (_Columba_) is plentiful. The gallinaceous birds are three

grouse, _Tetrao_ (two species) and _Bonasa_, and the common quail

(_Coturnix_).

The remaining genera and species of temperate or north-European birds, do

not usually range beyond the region of deciduous trees, roughly indicated

by the parallel of 60° north latitude.

Plate I.

[Illustration]

THE ALPS OF CENTRAL EUROPE, WITH CHARACTERISTIC ANIMALS.

{195}_Plate I.--Illustrating the Zoology of Central Europe._--Before

considering the distribution of the other classes of vertebrata, it will be

convenient to introduce our first illustration, which represents a scene in

the Alps of Central Europe, with figures of some of the most characteristic

Mammalia and Birds of this sub-region. On the left is the badger (_Meles

Taxus_) one of the weasel family, and belonging to a genus which is

strictly Palæarctic. It abounds in Central and Northern Europe and also

extends into North Asia, but is represented by another species in Thibet

and by a third in Japan. The elegantly-formed creatures on the right are

chamois (_Rupicapra tragus_), almost the only European antelopes, and

wholly confined to the higher mountains, from the Pyrenees to the

Carpathians and the Caucasus. The chamois is the only species of the genus,

and is thus perhaps the most characteristic European mammal. The bird on

the left, above the badgers, is the Alpine chough, (_Fregilus

pyrrhocorax_). It is found in the high mountains from the Alps to the

Himalayas, and is allied to the Cornish chough, which is still found on our

south-western coasts, and which ranges to Abyssinia and North China. The

Alpine chough differs in having a shorter bill of an orange colour, and

vermilion red feet as in the other species. In the foreground are a pair of

ruffs (_Machetes pugnax_) belonging to the Scolopacidæ or snipe family, and

most nearly allied to the genus _Tringa_ or sandpiper. This bird is

remarkable for the fine collar of plumes which adorns the males in the

breeding season, when they are excessively pugnacious. It is the only

species of its genus, and ranges over all Europe and much of Northern Asia,

migrating in the winter to the plains of India, and even down the east

coast of Africa as far as the Cape of Good Hope; but it only breeds in the

Palæarctic region, over the greater part of which it ranges.

_Reptiles and Amphibia._--There are no genera of reptiles peculiar to this

sub-region. Both snakes and lizards are comparatively scarce, there being

about fourteen species of the former and twelve of the latter. Our common

snake (_Tropidonotus natrix_) extends into Sweden and North Russia, but the

viper (_Viperus berus_) goes further north, as far as Archangel (64° N.),

and in Scandinavia (67° N.), and is the most Arctic of all known

{196}snakes. Of the lizards, _Lacerta stirpium_ (the sand lizard) has the

most northerly range, extending into Poland and Northern Russia; and

_Anguis fragilis_ (the blind or slow-worm) has almost an equal range.

Amphibia, being more adapted to a northern climate, have acquired a more

special development, and thus several forms are peculiar to the North

European sub-region. Most remarkable is _Proteus_, a singular eel-like

aquatic creature with small legs, found only in the subterranean lakes in

Carniola and Carinthia; _Alytes_, a curious toad, the male of which carries

about the eggs till they are hatched, found only in Central Europe from

France to the east of Hungary; and _Pelodytes_, a frog found only in

France. Frogs and toads are very abundant all over Europe, the common frog

(_Rana temporaria_) extending to the extreme north. The newts (_Triton_)

are also very abundant and widely spread, though not ranging so far north

as the frogs. The genera _Bombinator_ (a toad-like frog), and _Hyla_ (the

tree frog) are also common in Central Europe.

_Freshwater Fish._--Two genera of the perch family (Percidæ) are peculiar

to this sub-region,--_Percarina_, a fish found only in the river Dniester,

and _Aspro_, confined to the rivers of Central Europe. Of the very

characteristic forms are, _Gasterosteus_ (stickle-back), which alone forms

a peculiar family--Gasterosteidæ; _Perca_, _Acerina_ and _Lucioperca_,

genera of the perch family; _Silurus_, a large fish found in the rivers of

Cenrtal Europe, of the family Siluridæ; _Esox_ (the pike), of the family

Esocidæ; _Cyprinus_ (carp), _Gobio_ (gudgeon), _Leuciscus_ (roach, chub,

dace, &c.), _Tinca_ (tench), _Abramus_ (bream), _Alburnus_ (bleak),

_Cobitis_ (loach), all genera of the family Cyprinidæ.

_Insects--Lepidoptera._--No genera of butterflies are actually confined to

this sub-region, but many are characteristic of it. _Parnassius_, _Aporia_,

_Leucophasia_, _Colias_, _Melitæa_, _Argynnis_, _Vanessa_, _Limenitis_, and

_Chionobas_, are all very abundant and widespread, and give a feature to

the entomology of most of the countries included in it.

_Coleoptera._--This sub-region is very rich in Carabidæ; the genera

_Elaphrus_, _Nebria_, _Carabus_, _Cychrus_, _Pterostichus_, _Amara_,

{197}_Trechus_ and _Peryphus_ being especially characteristic. Staphylinidæ

abound. Among Lamellicorns the genus _Aphodius_ is most characteristic.

Buprestidæ are scarce; Elateridæ more abundant. Among Malacoderms

_Telephorus_ and _Malachius_ are characteristic. Curculionidæ abound:

_Otiorhyuchus_, _Omias_, _Erirhinus_, _Bagous_, _Rhynchites_ and

_Ceutorhynchus_ being very characteristic genera. Of Longicorns

_Callidium_, _Dorcadion_, _Pogonochærus_, _Pachyta_ and _Leptura_ are

perhaps the best representatives. _Donacia_, _Crioceris_, _Chrysomela_, and

_Altica_, are typical Phytophaga; while _Coccinella_ is the best

representative of the Securipalpes.

_North European Islands._--The British Islands are known to have been

recently connected with the Continent, and their animal productions are so

uniformly identical with continental species as to require no special note.

The only general fact of importance is, that the number of species in all

groups is much less than in continental districts of equal extent, and that

this number is still farther diminished in Ireland. This may be accounted

for by the smaller area and less varied surface of the latter island; and

it may also be partly due to the great extent of low land, so that a very

small depression would reduce it to the condition of a cluster of small

islands capable of supporting a very limited amount of animal life. Yet

further, if after such a submergence had destroyed much of the higher forms

of life in Great Britain and Ireland, both were elevated so as to again

form part of the Continent, a migration would commence by which they would

be stocked afresh; but this migration would be a work of time, and it is to

be expected that many species would never reach Ireland or would find its

excessively moist climate unsuited to them.

Some few British species differ slightly from their continental allies, and

are considered by many naturalists to be distinct. This is the case with

the red grouse (_Lagopus scoticus_) among birds; and a few of the smaller

Passeres have also been found to vary somewhat from the allied forms on the

Continent, showing that the comparatively short interval since the glacial

period, and the slightly different physical conditions dependent on

{198}insularity, have sufficed to commence the work of specific

modification. There are also a few small land-shells and several insects

not yet found elsewhere than in Britain; and even one of the smaller

Mammalia--a shrew (_Sorex rusticus_). These facts are all readily explained

by the former union of these islands with the Continent, and the alternate

depressions and elevations which are proved by geological evidence to have

occurred, by which they have been more than once separated and united again

in recent times. For the evidence of this elevation and depression, the

reader may consult Sir Charles Lyell's _Antiquity of Man_.

Iceland is the only other island of importance belonging to this

sub-region, and it contrasts strongly with Great Britain, both in its

Arctic climate and oceanic position. It is situated just south of the

Arctic circle and considerably nearer Greenland than Europe, yet its

productions are almost wholly European. The only indigenous land mammalia

are the Arctic fox (_Canis lagopus_), and the polar bear as an occasional

visitant, with a mouse (_Mus islandicus_), said to be of a peculiar

species. Four species of seals visit its shores. The birds are more

interesting. According to Professor Newton, ninety-five species have been

observed; but many of these are mere stragglers. There are twenty-three

land, and seventy-two aquatic birds and waders. Four or five are peculiar

species, though very closely related to others inhabiting Scandinavia or

Greenland. Only two or three species are more nearly related to Greenland

birds than to those of Northern Europe, so that the Palæarctic character of

the fauna is unmistakable. The following lists, compiled from a paper by

Professor Newton, may be interesting as showing more exactly the character

of Icelandic ornithology.

1. Peculiar species.--_Troglodytes borealis_ (closely allied to the common

wren, found also in the Faroe Islands); _Falco islandicus_ (closely allied

to _F. gyrfalco_); _Lagopus islandorum_ (closely allied to _L. rupestris_

of Greenland).

2. European species resident in Iceland.--_Emberiza nivalis_, _Corvus

corax_, _Haliæetus albicilla_, _Rallus aquaticus_, _Hæmatopus ostralegus_,

_Cygnus ferus_, _Mergus_ (two species), _Phalacocorax_ (two {199}species),

_Sula bassana_, _Larus_ (two species), _Stercorarius catarractes_,

_Puffinus anglorum_, _Mergulus alle_, _Uria_ (three species), _Alca torda_.

3. American species resident in Iceland.--_Clangula islandica_,

_Histrionicus torquatus_.

4. Annual visitants from Europe.--_Turdus iliacus_, _Ruticilla tithys_,

_Saxicola ænanthe_, _Motacilla alba_, _Anthus pratensis_, _Linota linaria_,

_Chelidon urbica_, _Hirundo rustica_, _Falco æsalon_, _Surnia nyctea_,

_Otus brachyotus_, _Charadrius pluvialis_, _Ægialites hiaticula_,

_Strepsilas interpres_, _Phalaropus fulicarius_, _Totanus calidris_,

_Limosa_ (species), _Tringa_ (three species), _Calidris arenaria_,

_Gallinago media_, _Numenius phæopus_, _Ardea cinerea_, _Anser_ (two

species), _Bernicla_ (two species), _Anas_ (four species), _Fuligula

marila_, _Harelda glacialis_, _Somateria mollissima_, _Oedemia nigra_,

_Sterna macrura_, _Rissa tridactyla_, _Larus luecopterus_, _Stercorarius_

(two species), _Fratercula artica_, _Colymbus_ (two species), _Podiceps

cornutus_.

5. Annual visitant from Greenland.--_Falco candicans_.

6.--Former resident, now extinct.--_Alca impennis_ (the great auk).

_II.--Mediterranean Sub-region._

This is by far the richest portion of the Palæarctic region, for although

of moderate extent much of it enjoys a climate in which the rigours of

winter are almost unknown. It includes all the countries south of the

Pyrenees, Alps, Balkans, and Caucasus mountains; all the southern shores of

the Mediterranean to the Atlas range, and even beyond it to include the

extra-tropical portion of the Sahara; and in the Nile valley as far as the

second cataract. Further east it includes the northern half of Arabia and

the whole of Persia, as well as Beluchistan, and perhaps Affghanistan up to

the banks of the Indus. This extensive district is almost wholly a region

of mountains and elevated plateaus. On the west, Spain is mainly a

table-land of more than 2000 feet elevation, deeply penetrated by extensive

valleys and rising into lofty mountain chains. Italy, Corsica, Sardinia,

and Sicily, are all very {200}mountainous, and much of their surface

considerably elevated. Further east we have all European Turkey and Greece,

a mountain region with a comparatively small extent of level plain. In Asia

the whole country, from Smyrna through Armenia and Persia to the further

borders of Affghanistan, is a vast mountainous plateau, almost all above

2000, and extensive districts above 5000 feet in elevation. The only large

tract of low-land is the valley of the Euphrates. There is also some

low-land south of the Caucasus, and in Syria the valley of the Jordan. In

North Africa the valley of the Nile and the coast plains of Tripoli and

Algiers are almost the only exceptions to the more or less mountainous and

plateau-like character of the country. Much of this extensive area is now

bare and arid, and often even of a desert character; a fact no doubt due,

in great part, to the destruction of aboriginal forests. This loss is

rendered permanent by the absence of irrigation, and, it is also thought,

by the abundance of camels and goats, animals which are exceedingly

injurious to woody vegetation, and are able to keep down the natural growth

of forests. Mr. Marsh (whose valuable work _Man and Nature_ gives much

information on this subject) believes that even large portions of the

African and Asiatic deserts would become covered with woods, and the

climate thereby greatly improved, were they protected from these

destructive domestic animals, which are probably not indigenous to the

country. Spain, in proportion to its extent, is very barren; Italy and

European Turkey are more woody and luxuriant; but it is perhaps in Asia

Minor, on the range of the Taurus, along the shores of the Black Sea, and

to the south of the Caucasus range, that this sub-region attains its

maximum of luxuriance in vegetation and in animal life. From the Caspian

eastward extends a region of arid plains and barren deserts, diversified by

a few more fertile valleys, in which the characteristic flora and fauna of

this portion of the Palæarctic region abounds. Further east we come to the

forests of the Hindoo Koosh, which probably form the limit of the

sub-region. Beyond these we enter on the Siberian sub-region to the north,

and on the outlying portion of the Oriental region on the south.

{201}In addition to the territories now indicated as forming part of the

Mediterranean sub-region, we must add the group of Canary Islands off the

west coast of Africa which seem to be an extension of the Atlas mountains,

and the oceanic groups of Madeira and the Azores; the latter about 1,000

miles from the continent of Europe, yet still unmistakably allied to it

both in their vegetable and animal productions. The peculiarities of the

faunas of these islands will be subsequently referred to.

It seems at first sight very extraordinary, that so large and wide a sea as

the Mediterranean should not separate distinct faunas, and this is the more

remarkable when we find how very deep the Mediterranean is, and therefore

how ancient we may well suppose it to be. Its eastern portion reaches a

depth of 2,100 fathoms or 12,600 feet, while its western basin is about

1,600 fathoms or 9,600 feet in greatest depth, and a considerable area of

both basins is more than 1,000 fathoms deep. But a further examination

shows, that a comparatively shallow sea or submerged bank incloses Malta

and Sicily, and that on the opposite coast a similar bank stretches out

from the coast of Tripoli leaving a narrow channel the greatest depth of

which is 240 fathoms. Here therefore is a broad plateau, which an elevation

of about 1,500 feet would convert into a wide extent of land connecting

Italy with Africa; while the same elevation would also connect Morocco with

Spain, leaving two extensive lakes to represent what is now the

Mediterranean Sea, and affording free communication for land animals

between Europe and North Africa. That such a state of things existed at a

comparatively recent period, is almost certain; not only because a

considerable number of identical _species_ of mammalia inhabit the opposite

shores of the Mediterranean, but also because numerous remains of three

species of elephants have been found in caves in Malta,--now a small rocky

island in which it would be impossible for such animals to live even if

they could reach it. Remains of hippopotami are also found at Gibraltar,

and many other animals of African types in Greece; all indicating means of

communication between South Europe and North Africa which no longer exist.

(See Chapter VI. pp. 113-115.)

{202}_Mammalia._--There are a few groups of Palæarctic Mammalia that are

peculiar to this sub-region. Such are, _Dama_, the fallow deer, which is

now found only in South Europe and North Africa; _Psammomys_, a peculiar

genus of Muridæ, found only in Egypt and Palestine; while _Ctenodactylus_,

a rat-like animal classed in the South American family Octodontidæ,

inhabits Tripoli. Among characteristic genera not found in other

sub-regions, are, _Dysopes_, a bat of the family Noctilionidæ;

_Macroscelides_, the elephant shrew, in North Africa; _Genetta_, the civet,

in South Europe; _Herpestes_, the ichneumon, in North Africa and (?) Spain;

_Hyæna_, in South Europe; _Gazella_, _Oryx_, _Alcephalus_, and _Addax_,

genera of antelopes in North Africa and Palestine; _Hyrax_, in Syria; and

_Hystrix_, the porcupine, in South Europe. Besides these, the camel and the

horse were perhaps once indigenous in the eastern parts of the sub-region;

and a wild sheep (_Ovis musmon_) still inhabits Sardinia, Corsica, and the

mountains of the south-east of Spain. The presence of the large feline

animals--such as the lion, the leopard, the serval, and the hunting

leopard--in North Africa, together with several other quadrupeds not found

in Europe, have been thought by some naturalists to prove, that this

district should not form part of the Palæarctic region. No doubt several

Ethiopian groups and species have entered it from the south; but the bulk

of its Mammalia still remains Palæarctic, although several of the species

have Asiatic rather than European affinities. The _Macacus innuus_ is

allied to an Asiatic rather than an African group of monkeys, and thus

denotes an Oriental affinity. Ethiopian affinity is apparently shown by the

three genera of antelopes, by _Herpestes_, and by _Macroscelides_; but our

examination of the Miocene fauna has shown that these were probably derived

from Europe originally, and do not form any part of the truly indigenous or

ancient Ethiopian fauna. Against these, however, we have the occurrence in

North Africa of such purely Palæarctic and non-Ethiopian genera as _Ursus_,

_Meles_, _Putorius_, _Sus_, _Cervus_, _Dama_, _Capra_, _Alactaga_; together

with actual European or West Asiatic species of _Canis_, _Genetta_,

_Felis_, _Putorius_, _Lutra_, many bats, _Sorex_, _Crocidura_, _Crossopus_,

_Hystrix_, {203}_Dipus_, _Lepus_, and _Mus_. It is admitted that, as

regards every other group of animals, North Africa is Palæarctic, and the

above enumeration shows that even in Mammalia, the intermixture of what are

now true Ethiopian types is altogether insignificant. It must be

remembered, also, that the lion inhabited Greece even in historic times,

while large carnivora were contemporary with man all over Central Europe.

_Birds._--So many of the European birds migrate over large portions of the

region, and so many others have a wide permanent range, that we cannot

expect to find more than a few genera, consisting of one or two species,

each, confined to a sub-region; and such appear to be, _Lusciniola_ and

_Pyrophthalma_, genera of Sylviidæ. But many are characteristic of this, as

compared with other Palæarctic sub-regions; such as, _Bradyptetus_,

_Aedon_, _Dromoloea_, and _Cercomela_, among Sylviidæ; _Crateropus_ and

_Malacocercus_, among Timaliidæ; _Telophonus_ among Laniidæ; _Certhilauda_

and _Mirafra_ among larks; _Pastor_ among starlings; _Upupa_, the hoopoe;

_Halycon_ and _Ceryle_ among kingfishers; _Turnix_ and _Caccabis_ among

Gallinæ, and the pheasant as an indigenous bird; together with _Gyps_,

_Vultur_ and _Neophron_, genera of vultures. In addition to these, almost

all our summer migrants spend their winter in some part of this favoured

land, mostly in North Africa, together with many species of Central Europe

that rarely or never visit us. It follows, that a large proportion of all

the birds of Europe and Western Asia are to be found in this sub-region, as

will be seen by referring to the list of the genera of the region.

Palestine is one of the remote portions of this region which has been well

explored by Canon Tristram, and it may be interesting to give his summary

of the range of the birds. We must bear in mind that the great depression

of the Dead Sea has a tropical climate, which accounts for the presence

here only, of such a tropical form as the sun-bird (_Nectarinea osea_).

The total number of the birds of Palestine is 322, and of these no less

than 260 are European, at once settling the question of the general

affinities of the fauna. Of the remainder eleven belong to North and East

Asia, four to the Red Sea, and {204}thirty-one to East Africa, while

twenty-seven are peculiar to Palestine. It is evident therefore that an

unusual number of East African birds have extended their range to this

congenial district, but most of these are desert species and hardly true

Ethiopians, and do not much interfere with the general Palæarctic character

of the whole assemblage. As an illustration of how wide-spread are many of

the Palæarctic forms, we may add, that seventy-nine species of land birds

and fifty-five of water birds, are common to Palestine and Britain. The

Oriental and Ethiopian genera _Pycnonotus_ and _Nectarinea_ are found here,

while _Bessornis_ and _Dromolæa_ are characteristically Ethiopian. Almost

all the other genera are Palæarctic.

Persia is another remote region generally associated with the idea of

Oriental and almost tropical forms, but which yet undoubtedly belongs to

the Palæarctic region. Mr. Blanford's recent collections in this country,

with other interesting information, is summarised in Mr. Elwes's paper on

the "Geographical Distribution of Asiatic Birds" (_Proc. Zool. Soc._ 1873,

p. 647). No less than 127 species are found also in Europe, and

thirty-seven others belong to European genera; seven are allied to birds of

Central Asia or Siberia, and fifteen to those of North-East Africa, while

only three are purely of Indian affinities. This shows a preponderance of

nearly nine-tenths of Palæarctic forms, which is fully as much as can be

expected in any country near the limits of a great region.

_Reptiles and Amphibia._--The climatal conditions being here more

favourable to these groups, and the genera being often of limited range, we

find some peculiar, and several very interesting forms. _Rhinechis_, a

genus of Colubrine snakes, is found only in South Europe; _Trogonophis_,

one of the Amphisbænians--curious snake-like lizards--is known only from

North Africa; _Psammosaurus_, belonging to the water lizards (Varanidæ) is

found in North Africa and North-West India; _Psammodromus_, a genus of

Lacertidæ, is peculiar to South Europe; _Hyalosaurus_, belonging to the

family Zonuridæ, is a lizard of especial interest, as it inhabits North

Africa while its nearest ally is the _Ophisaurus_ or "glass snake" of North

America; the family of {205}the scinks is represented by _Scincus_ found in

North Africa and Arabia. Besides these _Seps_, a genus of sand lizards

(Sepidæ) and _Agama_, a genus of Agamidæ, are abundant and characteristic.

Of Amphibia we have _Seiranota_, a genus of salamanders found only in Italy

and Dalmatia; _Chioglossa_, in Portugal, and _Geotriton_, in Italy,

belonging to the same family, are equally peculiar to the sub-region.

_Freshwater Fish._--One of the most interesting is _Tellia_, a genus of

Cyprinodontidæ found only in alpine pools in the Atlas mountains.

_Paraphoxinius_, found in South-East Europe, and _Chondrostoma_, in Europe

and Western Asia, genera of Cyprimidæ, seem almost peculiar to this

sub-region.

_Insects--Lepidoptera._--Two genera of butterflies, _Thais_ and _Doritis_,

are wholly confined to this sub-region, the former ranging over all

Southern Europe, the latter confined to Eastern Europe and Asia Minor.

_Anthocharis_ and _Zegris_ are very characteristic of it, the latter only

extending into South Russia, while _Danais_, _Charaxes_, and _Libythea_ are

tropical genera unknown in other parts of Europe.

_Coleoptera._--This sub-region is very rich in many groups of Coleoptera,

of which a few only can be noticed here. Among Carabidæ it possesses

_Procerus_ and _Procrustes_, almost exclusively, while _Brachinus_,

_Cymindis_, _Lebia_, _Graphipterus_, _Scarites_, _Chlænius_, _Calathus_,

and many others, are abundant and characteristic. Among

Lamellicorns--Copridæ, Glaphyridæ, Melolonthidæ, and Cetoniidæ abound.

Buprestidæ are plentiful, the genera _Julodis_, _Acmæodera_, _Buprestis_,

and _Sphenoptera_ being characteristic. Among Malacoderms--Cebrionidæ,

Lampyridæ, and Malachiidæ abound. The Tenebrioid Heteromera are very varied

and abundant, and give a character to the sub-region. The Mylabridæ,

Cantharidæ, and Oedemeridæ are also characteristic. Of the immense number

of Curculionidæ--_Thylacites_, _Brachycerus_, _Lixus_, and _Acalles_ may be

mentioned as among the most prominent. Of Longicorns there are few genera

especially characteristic, but perhaps _Prinobius_, _Purpuricenus_,

_Hesperophanes_, and _Parmena_ are most so. Of the remaining families, we

may mention Clythridæ, Hispidæ, and Cassididæ as being abundant.

{206}_The Mediterranean and Atlantic Islands._--The various islands of the

Mediterranean are interesting to the student of geographical distribution

as affording a few examples of local species of very restricted range, but

as a rule they present us with exactly the same forms as those of the

adjacent mainland.[6] Their peculiarities do not, therefore, properly come

within the scope of this work. The islands of the Atlantic Ocean belonging

to this sub-region are, from their isolated position and the various

problems they suggest, of much more interest, and their natural history has

been carefully studied. We shall therefore give a short account of their

peculiar features.

Of the three groups of Atlantic islands belonging to this sub-region, the

Canaries are nearest to the Continent, some of the islands being only about

fifty miles from the coast of Africa. They are, however, separated from the

mainland by a very deep channel (more than 5,000 feet), as shown on our

general map. The islands extend over a length of 300 miles; they are very

mountainous and wholly volcanic, and the celebrated peak of Teneriffe rises

to a height of more than 12,000 feet. The small Madeira group is about 400

miles from the coast of Morocco and 600 from the southern extremity of

Portugal; and there is a depth of more than 12,000 feet between it and the

continent. The Azores are nearly 1,000 miles west of Lisbon. They are quite

alone in mid-Atlantic, the most westerly islands being nearer Newfoundland

than Europe, and are surrounded by ocean depths of from 12,000 to 18,000

feet. It will be convenient to take these islands first in order.

_Azores._--Considering the remoteness of this group from every other land,

it is surprising to find as many as fifty-three species of birds inhabiting

or visiting the Azores; and still more to {207}find that they are of

Palæarctic genera and, with one exception, all of species found either in

Europe, North Africa, Madeira, or the Canaries. The exception is a

bullfinch peculiar to the islands, but closely allied to a European

species. Of land birds there are twenty-two, belonging to twenty-one

genera, all European. These genera are _Cerchneis_, _Buteo_, _Asio_,

_Strix_, _Turdus_, _Oriolus_, _Erithacus_, _Sylvia_, _Regulus_, _Saxicola_,

_Motacilla_, _Plectrophanes_, _Fringilla_, _Pyrrhula_, _Serinus_,

_Sturnus_, _Picus_, _Upupa_, _Columba_, _Caccabis_, and _Coturnix_. Besides

the bullfinch (_Pyrrhula_) other species show slight differences from their

European allies, but not such as to render them more than varieties. The

only truly indigenous mammal is a bat of a European species. Nine

butterflies inhabit the Azores; eight of them are European species, one

North American. Of beetles 212 have been collected, of which no less than

175 are European species; of the remainder, nineteen are found in the

Canaries or Madeira, three in South America, while fourteen are peculiar to

the islands.

Now these facts (for which we are indebted to Mr. Godman's _Natural History

of the Azores_) are both unexpected and exceedingly instructive. In most

other cases of remote Oceanic islands, a much larger proportion of the

fauna is endemic, or consists of peculiar species and often of peculiar

genera; as is well shown by the case of the Galapagos and Juan Fernandez,

both much nearer to a continent and both containing peculiar genera and

species of birds. Now we know that the cause and meaning of this difference

is, that in the one case the original immigration is very remote and has

never or very rarely been repeated, so that under the unchecked influence

of new conditions of life the species have become modified; in the other

case, either the original immigration has been recent, or if remote has

been so frequently repeated that the new comers have kept up the purity of

the stock, and have not allowed time for the new conditions to produce the

effect we are sure they would in time produce if not counteracted. For Mr.

Godman tells us that many of the birds are modified--instancing the

gold-crested wren, blackcap, and rock dove--and he adds, that the

{208}modification all tends in one direction--to produce a more sombre

plumage, a greater strength of feet and legs, and a more robust bill. We

further find, that four of the land-birds, including the oriole,

snow-bunting, and hoopoe, are not resident birds, but straggle accidentally

to the islands by stress of weather; and we are told that every year some

fresh birds are seen after violent storms. Add to this the fact, that the

number of species diminishes in the group as we go from east to west, and

that the islands are subject to fierce and frequent storms blowing from

every point of the compass,--and we have all the facts requisite to enable

us to understand how this remote archipelago has become stocked with animal

life without ever probably being much nearer to Europe than it is now. For

the islands are all volcanic, the only stratified rock that occurs being

believed to be of Miocene date.

_Madeira and the Canaries._--Coming next to Madeira, we find the number of

genera of land birds has increased to twenty-eight, of which seventeen are

identical with those of the Azores. Some of the commonest European

birds--swallows, larks, sparrows, linnets, goldfinches, ravens, and

partridges, are among the additions. A gold-crested warbler, _Regulus

Maderensis_, and a pigeon, _Columba Trocaz_, are peculiar to Madeira.

In the Canaries we find that the birds have again very much increased,

there being more than fifty genera of land birds; but the additions are

wholly European in character, and almost all common European species. We

find a few more peculiar species (five), while some others, including the

wild canary, are common to all the Atlantic Islands or to the Canaries and

Madeira. Here, too, the only indigenous mammalia are two European species

of bats.

_Land Shells._--The land shells of Madeira offer us an instructive contrast

to the birds of the Atlantic Islands. About fifty-six species have been

found in Madeira, and forty-two in the small adjacent island of Porto

Santo, but only twelve are common to both, and all or almost all are

distinct from their nearest allies in Europe and North Africa. Great

numbers of fossil shells are also found in deposits of the Newer Pliocene

period; and {209}although these comprise many fresh species, the two faunas

and that of the continent still remain almost as distinct from each other

as before. It has been already stated (p. 31) that the means by which land

mollusca have been carried across arms of the sea are unknown, although

several modes may be suggested; but it is evidently a rare event, requiring

some concurrence of favourable conditions not always present. The diversity

and specialization of the forms of these animals is, therefore, easily

explained by the fact, that, once introduced they have been left to

multiply under the influence of a variety of local conditions, which

inevitably lead, in the course of ages, to the formation of new varieties

and new species.

_Coleoptera._--The beetles of Madeira and the Canaries have been so

carefully collected and examined by Mr. T. V. Wollaston, and those of the

Azores described and compared by Mr. Crotch, and they illustrate so many

curious points in geographical distribution, that it is necessary to give

some account of them. No less than 1,480 species of beetles have been

obtained from the Canaries and Madeira, only 360 of which are European, the

remainder being peculiar to the islands. The Canaries are inhabited by a

little over 1,000 species, Madeira by about 700, while 240 are common to

both; but it is believed that many of these have been introduced by man. In

the Azores, 212 species have been obtained, of which 175 are European;

showing, as in the birds, as closer resemblance to the European fauna than

in the other islands which, although nearer to the continent, offer more

shelter and are situated in a less tempestuous zone. Of the non-European

species in the Azores, 19 are found also in the other groups of islands, 14

are peculiar, while 3 are American. Of the European species, 132 are found

also in the other Atlantic islands, while 43 have reached the Azores only.

This is interesting as showing to how great an extent the same insects

reach all the islands, notwithstanding the difference of latitude and

position; and it becomes of great theoretical importance, when we find how

many extensive families and genera are altogether absent.

The Madeira group has been more thoroughly explored than {210}any other,

and its comparatively remote situation, combined with its luxuriant

vegetation, have been favourable to the development and increase of the

peculiar forms which characterize all the Atlantic islands in a more or

less marked degree. A consideration of some of its peculiarities will,

therefore, best serve to show the bearing of the facts presented by the

insect fauna of the Atlantic islands, on the general laws of distribution.

The 711 species of beetles now known from the Madeira group, belong to 236

genera; and no less than 44 of these genera are not European but are

peculiar to the Atlantic islands. Most of them are, however, closely allied

to European genera, of which they are evidently modifications. A most

curious general feature presented by the Madeiran beetles, is the total

absence of many whole families and large genera abundant in South Europe.

Such are the Cicindelidæ, or tiger beetles; the Melolonthidæ, or chafers;

the Cetoniidæ, or rose-chafers; the Eumolpidæ and Galerucidæ, large

families of Phytophagous, or leaf-eating beetles; and also the extensive

groups of Elateridæ and Buprestidæ, which are each represented by but one

minute species. Of extensive genera abundant in South Europe, but wholly

absent in Madeira, are _Carabus_, _Rhizotrogus_, _Lampyris_, and other

genera of Malacoderms; _Otiorhynchus_, _Brachycerus_, and 20 other genera

of Curculionidæ, comprising more than 300 South European and North African

species; _Pimelia_, _Tentyra_, _Blaps_, and 18 other genera of Heteromera,

comprising about 550 species in South Europe and North Africa; and

_Timarcha_, containing 44 South European and North African species.

Another most remarkable feature of the Madeiran Coleoptera is the unusual

prevalence of apterous or wingless insects. This is especially the case

with groups which are confined to the Atlantic islands, many of which

consist wholly of wingless species; but it also affects the others, no less

than twenty-two genera which are usually or sometimes winged in Europe,

having only wingless species in Madeira; and even the same species which is

winged in Europe becomes, in at least three cases, wingless in Madeira,

without any other perceptible change having taken place. But there is

another most curious fact noticed by {211}Mr. Wollaston; that those species

which possess wings in Madeira, often have them rather larger than their

allies in Europe. These two facts were connected by Mr. Darwin, who

suggested that flying insects are much more exposed to be blown out to sea

and lost, than those which do not fly (and Mr. Wollaston had himself

supposed that the "stormy atmosphere" of Madeira had something to do with

the matter); so that the most frequent fliers would be continually weeded

out, while the more sluggish individuals, who either could not or would not

fly, remained to continue the race; and this process going on from

generation to generation, would, on the well-ascertained principles of

selection and abortion by disuse, in time lead to the entire loss of wings

by those insects to whom wings were _not a necessity_. But those whose

wings were essential to their existence would be acted upon in another way.

All these must fly to obtain their food or provide for their offspring, and

those that flew best would be best able to battle with the storms, and keep

themselves safe, and thus those with the longest and most powerful wings

would be preserved. If however all the individuals of the species were too

weak on the wing to resist the storms, they would soon become extinct.[7]

Now this explanation of the facts is not only simple and probable in

itself, but it also serves to explain in a remarkable manner some of the

peculiarities and deficiencies of the Madeiran insect fauna, in harmony

with the view (supported by the distribution of the birds and land shells,

and in particular by the immigrant birds and insects of the Azores) that

all the insects have been derived from the continent or from other islands,

by {212}immigration across the ocean, in various ways and during a long

period. These deficiencies are, on the other hand, quite inconsistent with

the theory (still held by some entomologists) that a land communication is

absolutely necessary to account for the origin of the Madeiran fauna.

First, then, we can understand how the tiger-beetles (Cicindelidæ) are

absent; since they are insects which have a short weak flight, but yet to

whom flight is necessary. If a few had been blown over to Madeira, they

would soon have become exterminated. The same thing applies to the

Melolonthidæ, Cetoniidæ, Eumolpidæ, and Galerucidæ,--all flower and

foliage-haunting insects, yet bulky and of comparatively feeble powers of

flight. Again, all the large genera abundant in South Europe, which have

been mentioned above as absent from Madeira, are wholly apterous (or

without wings), and thus their absence is a most significant fact; for it

proves that in the case of all insects of moderate size, flight was

essential to their reaching the island, which could not have been the case

had there been a land connection. There are, however, one or two curious

exceptions to the absence of these wholly apterous European genera in

Madeira, and as in each case the reason of their being exceptions can be

pointed out, they are eminently exceptions that prove the rule. Two of the

apterous species common to Europe and Madeira are found always in ants'

nests; and as ants, when winged, fly in great swarms and are carried by the

wind to great distances, they may have conveyed the minute eggs of these

very small beetles. Two European species of _Blaps_ occur in Madeira, but

these are house beetles, and are admitted to have been introduced by man.

There are also three species of _Meloe_, of which two are European and one

peculiar. These are large, sluggish, wingless insects, but they have a most

extraordinary and exceptional metamorphosis, the larvae in the first state

being minute active insects parasitic on bees, and thus easily conveyed

across the ocean. This case is most suggestive, as it accounts for what

would be otherwise a difficult anomaly. Another case, not quite so easily

explained, is that of the genus _Acalles_, which is very abundant in all

the Atlantic {213}islands and also occurs in South Europe, but is always

apterous. It is however closely allied to another genus, _Cryptorhynchus_,

which is apterous in some species, winged in others. We may therefore well

suppose that the ancestors of _Acalles_ were once in the same condition,

and that some of the winged forms reached Madeira, the genus having since

become wholly apterous.

We may look at this curious subject in another way. The Coleoptera of

Madeira may be divided into those which are found also in Europe or the

other islands, and those which are peculiar to it. On the theory of

introduction by accidental immigration across the sea, the latter must be

the more ancient, since they have had time to become modified; while the

former are comparatively recent, and their introduction may be supposed to

be now going on. The peculiar influence of Madeira in aborting the wings

should, therefore, have acted on the ancient and changed forms much more

powerfully than on the recent and unchanged forms. On carefully comparing

the two sets of insects (omitting those which have almost certainly been

introduced by man) we find, that out of 263 species which have a wide

range, only 14 are apterous; while the other class, consisting of 393

species, has no less than 178 apterous; or about 5 per cent in the one

case, and 45 per cent in the other.[8] On the theory of a land connection

as the main agent in introducing the fauna, both groups must have been

introduced at or about the same time, and why one set should have lost

their wings and the other not, is quite inexplicable.

Taking all these singular facts, in connection with the total absence of

all truly indigenous terrestrial mammalia and reptiles from these

islands--even from the extensive group of the Canaries so comparatively

near to the continent, we are forced to reject the theory of a land

connection as quite untenable; and this view becomes almost demonstrated by

the case of the Azores, which being so much further off, and surrounded by

such a vast expanse of deep ocean, could only have been {214}connected with

Europe at a far remoter epoch, and ought therefore to exhibit to us a fauna

composed almost entirely of peculiar forms both of birds and insects. Yet,

so far from this being the case, the facts are exactly the reverse. Far

more of the birds and insects are identical with those of Europe than in

the other islands, and this difference is clearly traced to the more

tempestuous atmosphere, which is shown to be even now annually bringing

fresh immigrants (both birds and insects) to its shores. We here see nature

actually at work; and if the case of Madeira rendered her mode of action

probable, that of the Azores may be said to demonstrate it.

Mr. Wollaston has objected to this view that "storms and hurricanes" are

somewhat rare in the latitude of Madeira and the Canaries; but this little

affects the question, since the _time_ allowed for such operations is so

ample. If but one very violent storm happened in a century, and ten such

storms recurred before a single species of insect was introduced into

Madeira, that would be more than sufficient to people it, as we now find

it, with a varied fauna. But he also adds the important information that

the ordinary winds blow almost uninterruptedly from the north-east, so that

there would be always a chance of a little stronger wind than usual

bringing insect, or larva, or egg, attached to leaves or twigs. Neither Mr.

Wollaston, Mr. Crotch, Mr. A. Murray, nor any other naturalist who upholds

the land-connection theory, has attempted to account for the fact of the

absence of so many extensive groups of insects that ought to be present, as

well as of all small mammalia and reptiles.

_Cape Verd Islands._--There is yet another group of Atlantic islands which

is very little known, and which is usually considered to be altogether

African--the Cape Verd Islands, situated between 300 and 400 miles west of

Senegal, and a little to the south of the termination of the Sahara. The

evidence that we possess as to the productions of these islands, shows

that, like the preceding groups, they are truly oceanic, and have probably

derived their fauna from the desert and the Canaries to the north-east of

them rather than from the fertile and more truly {215}Ethiopian districts

of Senegal and Gambia to the east. There is a mingling of the two faunas,

but the preponderance seems to be undoubtedly with the Palæarctic rather

than with the Ethiopian. I owe to Mr. R. B. Sharpe of the British Museum, a

MS. list of the birds of these islands, twenty-three species in all. Of

these eight are of wide distribution and may be neglected. Seven are

undoubted Palæarctic species, viz.:--_Milvus ictinus_, _Sylvia

atricapilla_, _S. conspicillata_, _Corvus corone_, _Passer salicarius_,

_Certhilauda desertorum_, _Columba livia_. Three are peculiar species, but

of Palæarctic genera and affinities, viz.:--_Calamoherpe brevipennis_,

_Ammomanes cinctura_, and _Passer jagoensis_. Against this we have to set

two West African species, _Estrilda cinerea_ and _Numida meleagris_, both

of which were probably introduced by man; and three which are of Ethiopian

genera and affinities, viz.:--_Halcyon erythrorhyncha_, closely allied to

_H. semicærulea_ of Arabia and North-east Africa, and therefore almost

Palæarctic; _Accipiter melanoleucus_; and _Pyrrhulauda nigriceps_, an

Ethiopian form; but the same species occurs in the Canaries.

The Coleoptera of these islands have been also collected by Mr. Wollaston,

and he finds that they have generally the same European character as those

of the Canaries and Madeira, several of the peculiar Atlantic genera, such

as _Acalles_ and _Hegeter_, occurring, while others are represented by new

but closely allied genera. Out of 275 species 91 were found also in the

Canaries and 81 in the Madeiran group; a wonderful amount of similarity

when we consider the distance and isolation of these islands and their

great diversity of climate and vegetation.

This connection of the four groups of Atlantic islands now referred to,

receives further support from the occurrence of land-shells of the subgenus

_Leptaxis_ in all the groups, as well as in Majorca; and by another

subgenus, _Hemicycla_, being common to the Canaries and Cape Verd islands.

Combining these several classes of facts, we seem justified in extending

the Mediterranean sub-region to include the Cape Verd Islands.

{216}_III.--The Siberian Sub-region, or Northern Asia._

This large and comparatively little-known subdivision of the Palæarctic

region, extends from the Caspian Sea to Kamschatka and Behring's Straits, a

distance of about 4,000 miles; and from the shores of the Arctic Ocean to

the high Himalayas of Sikhim in North Latitude 29°, on the same parallel as

Delhi. To the east of the Caspian Sea and the Ural Mountains is a great

extent of lowland which is continued round the northern coast, becoming

narrower as it approaches the East Cape. Beyond this, in a general E.N.E.

direction, rise hills and uplands, soon becoming lofty mountains, which

extend in an unbroken line from the Hindu Koosh, through the Thian Shan,

Altai and Yablonoi Mountains, to the Stanovoi range in the north-eastern

extremity of Asia. South of this region is a great central basin, which is

almost wholly desert; beyond which again is the vast plateau of Thibet,

with the Kuenlun, Karakorum, and Himalayan snow-capped ranges, forming the

most extensive elevated district on the globe.