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. [Illustration: POLATOUCHE.]