RODENTIA. MURID^. 69 



of fruit, nuts, &c., but seeks them on the ground, and lays up an 

 abundant store. It ascends trees to conceal itself when pursued, 

 if no other way of escape presents itself; but, if alarmed, it 

 escapes from its place of refuge at all hazards, with an instinctive 

 knowledge, that the place of greatest safety is its burrow. It 

 does considerable injury to corn fields when the plant is just out 

 of the ground, by destroying the kernel. 



Genus Pteromys. Illiger. 



Generic characters. Dental system ; incisors | ; canines f=^ ; 

 molars |=f ; = 22. Skin of the sides extended between the an- 

 terior and posterior extremities, so as to form a sail ; tail mod- 

 erate, flattened, and distichous ; anterior feet four-toed, posterior 

 five-toed. 



1. Pteromys volucella. Lin. The Flying Squirrel. 



Pteromys volucella, Harlan, Fauna Am., p. 187. 

 The Common Flying Squirrel, Godman, Nat. Hist., ii. p. 146. 

 Figure ; Ibid., p. 143, f. 1. 



Specific characters. Color brownish-ash ; the under parts of 

 the body white, with a yellowish margin where the color of the 

 back and belly approach each other ; the four toes of the anterior 

 feet nearly equal ; the four of the posterior feet are also equal, or 

 nearly so, while the fifth or outside one is shortest. 



Description. Some individuals are darker than others, and the 

 upper side of the tail is fawn-colored ; the ears are large, thin, 

 and rounded, nearly naked ; mystachial bristles numerous ; eyes 

 black and prominent. This animal is about five inches in length, 

 and the tail three and a half, or nearly four. It is common 

 throughout the States, is nocturnal in its habits, and may be tamed. 

 It has a fine, soft, beautiful fur, more so than either of the species 

 of Squirrels. It builds its nest generally in hollow stumps or trees, 

 and sometimes in thick brush-wood. 



Genus Gerbillus. Desm. 



Generic characters. Dental system ; incisors | ; canines ^=| ; 

 molars f]^f ; = 16. Anterior extremities short; posterior long. 



