CHAPTER IX 



CARNIVORA (continued) 



Sub-Order: PINNIPEDIA. THE MARINE CARNIVORA 



This sub-order includes the Sea Lions, Walruses, and Seals, three 

 very distinct families of carnivorous animals addicted entirely to 

 existence in the water, and almost wholly marine in their habitat, 

 only entering fresh water when it is directly connected with the 

 sea. They are not modified for life in the water to such an 

 amazing extent as the whales ; they are, in fact, amphibious, 

 and always resort to land during the breeding season, if not 

 oftener, for repose. The descent and relationships of the Fin- 

 footed Carnivores is still a matter of perplexity to zoologists. 

 They differ from the Fissipede, or Separate-toed Carnivores, in 

 the structure and arrangement of their molar teeth. These in 

 the seals, sea lions, etc., are placed in a perfectly straight row, 

 and offer no resemblance either to the tuberculated molars of 

 the True Carnivores or to the exaggerated development of their 

 lobed carnassial teeth. They also never possess in the adult the 

 complete three pairs of incisors in both jaws, and the incisors 

 are most reduced in numbers in the lower jaw. In the least 

 specialised forms the formula is three pairs of incisors in the 

 upper jaw and two pairs in the lower. But if it be the case that 

 the milk dentition in the walrus shows three pairs of incisors in 

 both jaws, it would seem that too much stress need not be placed 

 on this diminution of the incisors as a point of difference between 

 the Pinnipede and the Fissipede Carnivora ; the more so as this 

 reduction in the lower incisors occurs in one genus of Otters and 



1S7 



