162 THE DISTRIBUTION OF 



eating seal {Lobodon carcinophaga), the sea-leopard 

 (Stenorhynchus leptonyx), which all occur in the region 

 of ice-pack, while the sea-elephant {MacrorUnus leo- 

 ninus), and the southern fur-seal {Otaria jvbata) occur 

 in sub-Antarctic seas as well as elsewhere. The fact 

 that all these different kinds of seals tend to occur in 

 cold regions cannot be ascribed wholly to deliberate 

 choice on their part, for the young of aU are bom on 

 the land, and the animals seek out places as free as 

 possible from molestation, which are more frequent in 

 polar seas than elsewhere. Since man joined their 

 enemies many species are being driven further and 

 further back into the inaccessible parts of the polar 

 seas, or have been virtually exterminated. 



The seals, walrus, and sea-otter, the last named 

 being a fur-bearing animal found off rocky coasts in 

 the North Pacific, are all carnivores which have taken 

 recently to the aquatic life, and are stiU bound to 

 terra firma at the breeding season. There are, how- 

 ever, twQ orders of mammals whose members are 

 entirely aquatic, their young being bom under water. 

 These are the Cetacea or whales and dolphins, and 

 the Sirenia or sea-cows. The former are powerful 

 swimmers, and are pelagic. Their only connexion with 

 shore is that the greater abundance of fish in shallow 

 water brings many of them to the vicinity of sub- 

 marine ' banks ', while the whalebone whales haunt 

 relatively shallow water in high latitudes, because of 

 the abimdance of small marine organisms there. 



The Sirenia include only two living animals, the 

 dugong (Hahcore) found in the Pacific and Indian 

 Oceans, and extending southwards to the shores of 

 Austraha, and the manatee (Manatus) which fives in 

 the estuaries of the great rivers which flow into the 



