466 



MARMOTS AND FLYING SQUIRRELS 



the genus. The Alpine IMarmot, A. rnurmotta, 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. lohac, 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. 



The genus Pteromys (of which the proper name, antedating 



Fig. 234. — Flying Squirrel. Pfxromys alborufus. x\. 



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 complicated, 

 seems to argue a different mode of nutrition. There are twelve 

 pairs of ribs. The large intestine (in P. 2Ji'/aiirista) 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. 



