The Geographical Distribution of Animals, Volume 1 / With a study of the relations of living and extinct faunas as elucidating the past changes of the Earth's surface

by Alfred Russel Wallace

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

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

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

CHAPTER X.

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.

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.