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tions 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, Trogonophido and Ophiomoridæ, and one of fishes, Comephorido. The number of peculiar genera is, however, considerable, as the following enumeration will show.
Mammalia.—The monkey of Gibraltar and North Africa, and an allied species found in Japan, are now considered to belong to the extensive eastern genus Macacus. The former, however, is peculiar in the entire absence of the tail, and has by many naturalists, been held to form a distinct genus, Inuus, confined to the Palæarctic region.
Of bats there are one or two genera (Barbastellus, Plecotus) which seem to be mainly or wholly Palæarctic, but the classification of these animals is in such an unsettled state that the distribution of the genera is of little importance.
In the next order, Insectivora, we have almost the entire family of the Moles confined to the region. Talpa just enters Northern India ; and Urotrichus is common to Japan and North
Western America, but the remaining genera, six in number, are all exclusively Palæarctic.
Among Carnivora we have Nyctereutes, the curious racoon-dog of Japan and North-Eastern Asia; Lutronectes, an otter peculiar to Japan; and the badger (Meles), which ranges over the whole region, and just enters the Oriental region as far as Hongkong; Æluropus, a curious form of the Himalayan panda, inhabiting the high mountains of Eastern Thibet; and Pelagius, a genus of seals, ranging from the shores of Madeira to the Black Sea.
The Ungulata, or hoofed animals, are still more productive of forms peculiar to this region. First we have the Camels, whose native home is the desert region of Central and Western Asia and Northern Africa, and which, even in their domesticated condition, are confined almost wholly within the limits of the Palæarctic region. Of Deer we have six peculiar genera, Dama and Capreolus found in Europe, with Elaphodus, Lophotragus, Hydropotes, and Moschus, confined to Northern China and Mongolia. The great family Bovidæ-comprising the oxen, sheep, goats and antelopes -furnishes no less than seven peculiar Palæarctic genera. These are Poephagus, the yak of Thibet; Addax, a well-known antelope of Northern Africa and Syria ; Procapra, Pantholops and Budorcas, antelopine genera peculiar to Thibet and Mongolia; with Rupicapra (the chamois), and the extraordinary large-nosed antelope Saiga, confined to Europe and Western Asia. Besides these we have Capra (the wild sheep and goats), all the numerous species of which, except two, are exclusively Palæarctic.
Coming to the Rodents, we have again many peculiar forms. Of Muridæ (the mouse and rat tribe), we have six peculiar genera, the more important being Cricetus, Rhombomys Sminthus, and Myospalax. Of Spalacidæ (mole-rats) both the Palæarctic genera, Ellobius and Spalax, are peculiar. Ctenodactylus, a genus of the South American family Octodontidæ, is found only in North Africa. To these we may add Myoxus (the dormice) and Lagomys (the pikas or tail-less hares) as essentially Palæarctic, since but one species of each genus is found beyond the limits of the region.
Birds.--It appears to have been the opinion of many natural