43 



PRACTICAL ZOOLOGY 



FIG. 296. The walrus. (From Flower 

 and Lydekker.) 



The seal family contains 

 a number of sped es, among 

 them the harbor seal, 

 which inhabits the North 

 Atlantic. 



Gnawing Animals. 

 The rodents are character- 

 ized by their long, chisel- 

 shaped incisor teeth which 

 are adapted for gnawing, 

 and the absence of canines, 

 leaving a gap between the 



incisors and premolars. They are all small or of moderate size 

 and constitute the largest order of mammals. The best-known 

 North American families are the rabbits and hares, the squirrels, 

 the beavers, the 

 pocket-gophers, 

 the rats, mice, 

 etc., and the por- 

 cupines. 



The squirrel 

 family includes 

 the woodchucks, 

 prairie dogs, tree 

 squirrels, chip- 

 munks, ground 

 squirrels, and 

 flying squirrels. 

 The common tree 

 squirrels (Fig. 

 297) are the gray, 

 fox and red squir- 

 rels ; these are 

 all excellent 



Climbers, and be- FIG. 297. Fox squirrel. (Photo, by Lyndon.) 



