Some nine or ten additional species of the genus Pteromys, which includes the Flying Squirrels with cylindrical tails, are found in the forest regions of India and of the countries to the east of that peninsula, including China, Formosa, and Japan. The same region also harbours three or four species of another kind of Flying Squirrel, in which the long hairs of the tail are arranged in two rows, and the tail is flat instead of cylindrical. These animals, to which the name of Sciuropterus has been given, are, however, more numerous in the north, where their distribution extends from Lapland and Finland, through Siberia, to Northern China and Japan. Squirrels of this genus also occur over the whole continent of North America and as far south as Guatemala. The best known of the Old World species is the POLATOUCHE (Sciuropterus volans), which inhabits the north-eastern parts of Europe and nearly the whole of Siberia. It is an elegant little creature, about six inches in length, and with a broad, flat tail, rather shorter than the body: as, indeed, is the case in all the Sciuropteri. Its silky coat is in summer of a tawny brown on the upper surface, darker on the flying membrane and the outsides of the limbs, beneath pure white; whilst the tail is greyish above and light rusty red beneath. In winter the fur becomes longer and thicker, and appears of a silver grey colour on the upper surface. The Polatouche lives in the birch woods, or in places where pines, firs, and birches grow intermingled; but the presence of the birch seems to be a necessity of its existence. It is met with singly or in pairs, but always on the trees, sleeping during the day in its nest or in the hole of a tree, and coming forth at dusk to climb and leap about the branches with great agility. In going from tree to tree by the aid of its lateral membranes, it is said to cover distances of twenty or thirty yards with ease, always, however, taking its leap from the highest branches of the tree it starts from, and alighting at a considerably lower level. Its food consists of nuts, seeds, berries, the buds, young shoots, and catkins of the birch, and the young shoots of pines and firs. The nest is made in the hole of a tree, carefully lined with soft moss and herbage. Like the Common Squirrel, the Polatouche sleeps through the cold weather, but wakes up from time to time and goes out in search of food.
POLATOUCHE.
This group of Flying Squirrels is also represented on the North American continent. The number of species seems rather uncertain, some authors making it two, others four; while Mr. J. A. Allen regards all the North American Flying Squirrels as belonging to a single species, which varies greatly in size in different localities. This species is the ASSAPAN (Sciuropterus volucella), one of the smallest of its family, the length of its head and body being only from four and three-quarters to seven and a half inches; the smaller specimens (var. volucella) being found in the more southern States, and even as far south as Guatemala; and the larger ones (var. hudsonius) in more northern localities. In its habits this elegant little Squirrel resembles the Polatouche, but appears to be more sociable. It thrives well in confinement.
Besides these Tree Squirrels, a few species of the Sciurine sub-family live upon the ground. In Abyssinia and in other parts of Africa some curious animals, forming the genus Xerus, are found, distinguished by their very small ears, longish limbs, and the singular texture of their hair, which scantily clothes the skin and generally takes the form of flattened spines. They have a slender body, a pointed head, and a longish tail. These animals live in elevated forest regions, and even upon comparatively barren steppes, where they burrow in the ground under rocks, or among the roots of trees and bushes. They are diurnal, and feed chiefly upon buds and herbage, but also devour small birds, eggs, and insects. The best known species (Xerus rutilans) is about twenty inches long, of which the tail makes about nine inches. Its colour is reddish-yellow above, becoming paler on the sides, and whitish below.
COMMON CHIPMUNK.
The true GROUND SQUIRRELS (Tamias) are distinguished from the rest of the Squirrels (Sciurinæ), and approach the Marmots, which form a second sub-family of Sciuridæ. Like some of the latter, they possess large cheek-pouches opening into the mouth. The ears in this genus are short; the fourth toe of the fore feet is longer than the rest, as in all the Sciurinæ; the limbs are short, and nearly equal in length; and the tail is shorter than in the true Squirrels. In general form and appearance, however, the Ground Squirrels greatly resemble the latter, except that they are rather stouter in the body. Four species of this group inhabit the continent of North America, where they are known as Chipmunks; and one of these, according to Mr. J. A. Allen, is identical with the only known Old World species (Tamias asiaticus), which is found in North-eastern Europe and across Northern Asia, as far as the mouth of the Amoor, North China, and Japan. This species, which goes by different names in the different localities which it inhabits, and the COMMON CHIPMUNK (Tamias striatus) of the United States, agree very closely in all respects, and are exceedingly pretty little animals, with light-coloured fur adorned with darker stripes, varied in the case of the Chipmunk with streaks of white. They are from eight to ten inches long, including the tail. These animals live in burrows in the ground, and feed upon nuts, acorns, grain, and other seeds of various kinds, of which they lay up great stores in the autumn, carrying home their provisions in their cheek-pouches, which they stuff as full as they can hold. In this way they do no small damage to cultivated grounds near their haunts, plundering the corn and maize fields very freely; over eight pounds of corn in the ear are often found in the granaries of the Siberian form. The burrow is made deep enough to protect the animals from frost in winter, and the sleeping chamber contains a large nest of leaves and grass, in which several individuals, probably the parents with their grown-up family, sleep through the cold weather; but it must be remarked that their torpidity is very imperfect, and that they have frequent recourse to the supplies of food which they have stored up during the summer and autumn in separate chambers at the ends of lateral passages. These stores are so large that they generally greatly exceed the wants of the provident little animals, and in the spring the residue is greedily devoured by Wild Pigs and Bears. Even the poorer human inhabitants of the countries frequented by the Ground Squirrels do not disdain to eke out their scanty means of subsistence by plundering the hoards of these animals. Many of them perish in severe winters, great numbers are destroyed by man, by the smaller Carnivora, and by birds of prey, but, nevertheless, they manage to hold their own, in consequence of the great fertility of the females, which produce several young twice in the year, namely, in May and August. At pairing time the males fight violently.
MOLAR TEETH OF THE MARMOT.