320 BACKBONED ANIMALS. 
that quantities of material are found there. A watch lost by a traveler 
was afterward found in front of a hole. 
Squirrels (Sciuride),— The squirrels have a wide 
geographical range. They have powerful, compressed in- 
cisor teeth, prominent ears, the snout and upper lip di- 
vided, and long tails with hairs generally arranged along 
the sides. The gray and black squirrels attain a length 
of two feet, including the tail, They vary much in color, 
from black to all shades of gray. The gray squirrels make 
wonderful migrations, passing over the country in vast num- 
Fic. 346.—American chipmunk, 
bers, swimming streams, and divesting the land as they pass. 
The tufted-eared squirrel, of the San Francisco Hills, is 
one of the finest American species. The striped squirrels 
(chipmunks) (Fig. 346) have enormous cheek-pouches, 
used in carrying food to their nests. The flying squir- 
tels (Fig. 340) have a fur-covered membrane, extending 
