120 ELEMENTS OF COMPARATIVE ZOOLOGY. 



which belong to Africa, but which are represented in 

 America by the prong-horned antelope of our Western 

 States. Other members of the same group with permanent 

 horns are the sheep and the goats, the series ending with 

 the so-called musk-ox of the arctic regions, a form nearer 

 the goats than to the domestic cattle in its structure. 



As a whole, we may say that in points in structure 

 especially in the characters of feet and teeth the group of 

 ungulates are among the most specialized of the mammalia, 

 the whales, bats, seals, and possibly the elephants alone ex- 

 celling them in this respect. 



ORDER X. CARNIVORA (Beasts of Prey). 



The beasts of prey are specialized in the direction of 

 flesh-eating. Their bones are slender, but strong; their 

 feet (usually five- toed) are furnished with claws; while on 

 the top of the skull is a crest for the attachment of the 

 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 fellow 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 carnivores^ 

 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, 



