MAMMALS. 121 



Lowest of the fissipedia are the bears and their allies, in 

 which the whole sole of the foot is applied to the ground in 

 walking, and hence are called plantigrade, in opposition to 

 those digitigrade forms, like the cat and dog, which walk 

 upon the tips of their toes. The bears are widely distrib- 

 uted over the earth, America having at least three species. 

 The racoon is distributed throughout the United States, 

 and in tropical America is represented by that exceedingly 

 interesting animal, the coati. 



Another group of carnivores includes the otters, mink, 

 ermine, sable, and marten all of which are valuable for the 

 furs which they afford, as well as the weasels and ferrets, 

 and the well-known skunks. These are partly plantigrade, 

 partly digitigrade. 



The dogs, foxes, wolves, and jackals are all digitigrade. 

 They have the teeth, i J, c ^, pm J, m f . Foxes and 

 wolves are wild, and many believe that our domestic dogs 

 have descended from some wolf stock; but others think 

 that dogs and wolves are distinct, and even that our common 

 dogs represent several originally distinct kinds or species. 



The hyaenas are intermediate between the cats and dogs 

 in many respects. They have the back teeth fitted for 

 crushing. In the cats, of which there are more than fifty 

 species, the teeth are usually i f , c -}-, pm f , m {, while 

 the claws are retractile into sheaths. Our domestic cat 

 apparently had its origin in Egypt, while ancient Greece and 

 Itcme lacked our familiar puss, its place being taken by 

 domesticated martens. Among the cats the tiger, lion, 

 panther, leopard, and puma rank first, and with them are 

 associated the wildcats and lynxes. 



In external form the seals and walruses have little re- 

 semblance to the other carnivores, but in structure, and 

 especially in their skulls, there is great resemblance to the 



