466 MARMOTS AND FLYING SQUIRRELS CHAP. 
the genus. The Alpine Marmot, 4. 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 Quebee Marmot, A. monaz. 
The genus Pteromys (of which the proper name, antedating 
Fic. 234.—Flying Squirrel. ~Pteromys alborufus. x4. 
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 sup- 
ported 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 complieated, 
seems to argue a different mode of nutrition. There are twelve 
pairs of ribs. The large intestine (in P. petawrista) 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. 
