200 



THE GEOGRAPHY OF MAMMALS 



embracing about nine different generic forms, are most 

 numerous in the Arctic and Antarctic Seas, but are also 

 feebly represented in some intermediate localities. Be- 

 ginning with the North Atlantic, we find several species of 

 Phoca (Fig. 43, p. 201), inhabiting various parts of this area, 

 and the Grey Seal (Halichaerus) and the Bladder-Seal 



Fig. 42. — The Atlantic Walrus. 

 (Trichcchus rosmarus.) 



(Cystophora) exclusively confined to it. In the North 

 Pacific all the four true Seals belong to the genus Phoca, 

 and three of them are identical with the North Atlantic 

 species ; but when we descend as far south as the Gulf 

 of California on the American coast we meet with a species 

 of Sea-elephant (Macrorhinus) which, like Otaria, has no 



