388 SYSTEMATIC ZOOLOGY. 



strong muscles of the jaws. All four kinds of teeth are 

 present, and one of the molars or premolars is flattened 

 vertically, so that, meeting its fellows of the opposite jaw, 

 it cuts like a pair of shears. In the lower mammals we 

 find the lower jaw so hinged upon the skull that it can 

 move back and forth in grinding the food. In the car- 

 nivores, on the other hand, no such motion is possible. 



The carnivores are divided into two groups, one embrac- 

 ing the typical land-inhabiting forms; the other, which 

 includes the walrus and the seals, is modified for an aquatic 

 life; the differences being most marked in the structure of 

 the appendages. In the first group the legs are elongate 

 and the toes are distinct, whence the name FISSIPEDIA; 

 while in the other division (PINNIPEDIA^ the legs are 

 shortened, the fingers are webbed, and the feet are thus 

 effective paddles. 



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 dis- 

 tributed over the earth, America having at least three 

 species. The raccoon 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, if, cf, praj, mf or f . Foxes and 

 wolves are wild, and many believe that our domestic dogs 



