TEE RODENTS. 



253 



well-formed ears, the Hudson Bay lemming {Cuniculiis 

 torquatus) has no external ears. It becomes pure white in 

 winter, while the lemmings do not change. It inhabits 

 the arctic regions of Asia and Europe as well as arctic 

 America and Greenland. In summer it burrows under 

 stones in dry ridges, and in the winter nests in the moss. 



Fio. 293. — Flying Squirrel (Sciuropterus volans), one half natural size. 



From their nest-building habits, rodents are, as a rule, not 

 unlike birds; and Oweu, fur these reasons, ascribes to them 

 a low degree of intelligence. Granting that this is the 

 case, an exception to this rule is seen in the social beavers, 

 which evince a high, exceptional degree of intelligence. 

 Beavers build a dam in a running stream so as to create an 



