546 



W' HALES 



Figure i8g. Covi- 

 rnerson's Dolphin 

 from the Straits of 

 Alagellan, one of 

 many species of the 

 genus Cephalo- 

 rhynchus. {Kellogg, 

 1940.) 



Bottlenose Dolphin, is particularly fond of estuaries and is rarely found 

 far from the coast, while species oï Steno (Rough-toothed Dolphins) which 

 occur in most warm seas, generally prefer deep water. The Finless Black 

 Porpoise, sometimes called the Indian Porpoise (see Fig. 187) is also found 

 over a wide area, from the Cape of Good Hope to Japan. It prefers coastal 

 w^aters, and especially likes lagoons and estuaries, so much so that, in 

 China, it travels up the Yangtze Kiang beyond the Tung Ting Lake, 

 more than a thousand miles from the sea. 



Dolphins of the genus Orcaella are coastal species with an even more 

 restricted distribution. They are mainly found in the Bay of Bengal, and 

 off Malacca and Thailand. Fresh water dolphins of the family Platanistidae, 

 all of which have unusually long and slender jaws, are all confined to 

 tropical and sub-tropical rivers, e.g. the Susu or Gangetic Dolphin 

 [Platanista gangetica) which lives in the rivers Ganges and Indus; the 

 Amazonian Dolphin or Boutu {Inia geoffrensis) which is found in the Upper 

 Amazon ; the La Plata Dolphin (Stenodelphis blahivillei) which occurs in the 

 River Plate; and the Chinese River Dolphin [Lipotes vexillifer) from the 

 Tung Ting Lake (see Fig. 188). 



Other Cetaceans are confined entirely to Arctic or Antarctic regions. 

 Thus Greenland Whales, Belugas and Narwhals occur in Arctic waters 

 alone, the Beluga being confined to regions north of the Polar Circle, at 

 least in Europe. In N. America and E. Asia, its southern boundaries are 

 60° N. and 50° N. respectively. Belugas are rarely found south of these 

 boundaries, and the same is largely true of Greenland Whales and 



