100 



SUBKINGDOM VERTEBRATA. 



Fig. 165. 



Pteromys wlucdla, Flying Squirrel. \. 



of the skin of the flank between the fore and the hind legs, 

 which, with the flattened tail, forms a parachute to sustain 

 it in leaping from tree to tree.* There is probably but one 

 species in North America, differing in color and size accord- 

 ing to locality. The Chipmunk, or Striped Squirrel, has 

 cheek-pouches opening internally outside the teeth, capable 



Fig. 166. Fig. 167. 



Tam/ias siriatw, Chipmunk, j. 



SpermopJ&lus tridtcem lineatus, 

 Striped Prairie Squirrel.t ?. 



* It is not flight, since the squirrel cannot propel itself in the air, nor even sus- 

 tain itself at the same height. The first impulse being given by its powerful hind 

 legs, it descends obliquely, and just before reaching the point aimed at, by an upward 

 movement of the tail and the impetus of its velocity, ascends a short distance, and 

 thus alights flat upon its four feet. 



t In Iowa, Minn., Wis., and northern Til., this squirrel is popularly known as the 

 Oopher. The true animal of this name is given on p. 97. The former is sometimes 

 destructive to crops in new districts, but a few pails of water will drive it out of its 

 shallow burrow : while it fully recompenses all its damage by destroying mice and 

 noxious insects. 



