MAMMALIA 455 



and South America which is the largest. Our native dogs are 

 the timber wolf, the coyote, the red fox, the blue fox, the gray 

 fox. We have several species of bears, polar, black, grizzly, 

 and cinnamon. 



The greatest of the cats are the tigers, which may reach a 

 length of ten feet, and the lions. These with the leopard are 

 Southern Asiatic and African types. 



The order embraces many very powerful and intelligent 

 animals which are well adapted to win in the struggle for life, 

 if it were not for human interference. In the presence of man, 

 however, all those which are not suited to domestication are 

 gradually disappearing; some because of their dangerous quali- 

 ties, others because of the value of their products. The group 

 is not used to any considerable extent as food. 



Order 7. Rodentia (gnawing animals). The rodents are 

 small mammals with clawed digits. They have no canine teeth, 



FIG. 239. 



FIG. 239. The Jumping Rat (Perodipus richardsoni) , adult male. Photographed from life by 



Dr. R. W. Shufeldt. 



Questions on the figure. What order of mammals is illustrated by this form? 

 What explanations are offered as to the cause of the light color of the belly and the 

 dark color of the backs of animals? Of what conceivable advantage is the differ- 

 ence in coloration? How does the tail of this species compare with that of our 

 common rat? 



