Dark Is Be j ore the Dawn 363 



gestion that dolphins should be called porpoises. The porpoises, and 

 there are several, are not just specialized forms of small dolphins; 

 they are quite different animals constituting a separate family called 

 the Fhocaenidae. 



Dolphins of popular terminology are included in a family of 

 whales rather obviously called the Delphinidae. Here, however, 

 comes a second complication, because this family includes a variety 

 of animals (see Appendix E for complete list), among which are 

 the killer, the false killer, and the pilot whale or blackfish, as well as 

 the true dolphins. This family is today organized by zoologists into 

 fourteen genera and contains, all told, about sixty quite distinct ani- 

 mals, among them some very strange creatures which are most per- 

 tinent to our story. The majority are of interest only to specialists. 

 If anyone should be interested further, he can find their names by 

 reference to the illustrations in Appendix E, and then pursue de- 

 tailed information on them in the works listed in the appropriate 

 portion of the bibliography. 



Finally, there is the quite distinct little family of tiny whales 

 known as the Platanistidae, sometimes popularly known as Fresh- 

 water Dolphins, which are of the utmost importance to our story. 

 Quite a number of marine dolphins, and all the porpoises, will enter 

 the mouths of rivers and pursue fish inland into purely fresh water. 

 They remain, nevertheless, basically marine animals, and they re- 

 turn to the sea to breed. There are others that dwell always in great 

 rivers, and almost every large tropical river system appears to have 

 some special breed of little whale, either a dolphin, a porpoise, or a 

 platanistid. 



Starting in South America, the La Plata has one platanistid called 

 Pontoporia blainvillei; the Amazon complex has the Boutu (Inia geof- 

 froyensis) and three different kinds of Sotalia, called locally the 

 Tucuxi (Sotalia tucuxi), the Buffeo Blanco {Sotalia pallida), and the 

 Buffeo Negro {Sotalia fluviatalis) . The rivers of the Guianas have be- 

 sides the boutu, still another species named Sotalia guianensis. In the 

 Cross River of the Cameroon, West Africa, lives an animal called 

 Sotalia teuszii which is unique in that nothing but grass, mangrove 

 leaves, aquatic plants, and some fruits have ever been found in its 

 stomach. In the Ganges and Indus rivers of India is found the Susu 

 {Platanista gangetica), which we have already described in detail as 



