the genus. The Alpine Marmot, A. marmotta, is familiar to most persons. The animal lives high up in the Alps, and when danger threatens it gives vent to a shrill whistle. It hibernates in the winter, and as many as ten to fifteen animals may be found closely packed together in a single, carefully-lined burrow.
The only other European species is A. bobac, the Siberian Marmot, which occurs in the extreme east of Europe, and is also Asiatic. There are four North American species, including the Quebec Marmot, A. monax.
Fig. 234.—Flying Squirrel. Pteromys alborufus. × 1⁄5.
The genus Pteromys (of which the proper name, antedating Pteromys by five years, appears to be Petaurista) is confined to the Oriental region, where there are a dozen species or so. The limbs are united by a parachute extending to the toes, and supported anteriorly by a cartilage attached to the wrists. There are also membranes anteriorly uniting the fore-limbs to the neck, and posteriorly uniting the hind-limbs to the root of the tail and a trifle beyond. The skull and the dental formula are as in Sciurus, but the pattern of the molars, which is much complicated, seems to argue a different mode of nutrition. There are twelve pairs of ribs. The large intestine (in P. petaurista) is very nearly as long as the small, and the caecum is also "colossal"; the measurements in an individual of the species named were: small intestine, 670 mm.; caecum, 320 mm.; large intestine, 650 mm.
