250 THE GEOGRAPHY OF MAMMALS 



Section V. — Distribution of the Marine Carnivora 



The Marine Carnivora, or Pinnipeds, which close the 

 series of mammals of this order, are, as has already been 

 shown, distributed on quite a different system from that 

 which prevails in the terrestrial groups of mammals. As, 

 however, they resort more or less to land for breeding 

 purposes, the laws which regulate their distribution are 

 more like those of terrestrial mammals than those which 

 guide the distribution of such purely oceanic forms as the 

 Cetaceans. We have already discussed the main facts of 

 the distribution of the Pinnipeds in a former chapter of 

 this work (Chapter VIII. sect. 2), and it is not now neces- 

 sary to repeat them, further than to point out that of the 

 three families comprised in this group the Otariidte, or 

 Sea-lions, are essentially Antarctic, only passing to the 

 north in the Pacific where three species occur. On the 

 other hand the Walruses (Trichechus), which are the sole 

 constituents of the second family Trichechidte, are still 

 more absolutely Arctic, being only found in the North 

 Atlantic and the North Pacific. The third family of Pin- 

 nipeds, of which about nine generic forms are recognized, 

 are, on the other hand, much more widely diffused, though 

 most prevalent in high and low latitudes and but feebly 

 represented within the tropics. It should be also specially 

 noted that the five known genera of Antarctic Pliocidte are 

 quite different from those of the Arctic seas, although one 

 of them (Macrorhinus) has wandered far up the coast of 

 Western America to the shores of Southern California. 



