CHAP. xvii. MAMMALIA. 209 



in both jaws. According to Dr. Gray they form seven families 

 and 24 genera ; according to Professor Cams, four sub-families 

 and 8 genera, but as these groups appear to be established on 

 quite different principles, and often differ widely from each other, 

 I shall simply enumerate Dr. Gray's genera with their distribu- 

 tion as given in his British Museum Catalogue. 



Platanista (2 species), long-snouted porpoises, inhabiting the 

 Ganges and Indus ; Inia (1 species), a somewhat similar form, 

 inhabiting the upper waters of the Amazonian rivers : Sleno 

 (8 species), Indian Ocean, Cape of Good Hope, and West Pacific ; 

 Sotalia (1 species), Guiana ; Delphinus (10 species), all the oceans ; 

 Clymenia (14 species), all the oceans ; Delphinapterus (1 species), 

 South Atlantic ; Tursio (7 species), Atlantic and Indian Oceans ; 

 Eutropia (2 species), Chili, and Cape of Good Hope ; Electro, (8 

 species), all the oceans ; Leucopleurus (1 species), North Sea ; 

 Lagenorhynchus (1 species), North Sea; Pseudorca (2 species), 

 North Sea, Tasmania ; Orc&ella (2 species), Ganges ; Acantho- 

 delphis (1 species), Brazil ; Phoccena (2 species), North Sea ; Neo- 

 meris (1 species), India ; Grampus (3 species), North Sea, Medi- 

 terranean, Cape of Good Hope ; Globiqceplialus (14 species), all 

 the oceans ; Sphcerocephalus (1 species), North Atlantic ; Orca 

 (9 species), Northern and Southern Oceans ; OpJiysia (1 species), 

 North Pacific ; Beluga (6 species), Arctic Seas, Australia ; Pon- 

 toporia (1 species), Monte Video. 



Fossil Cetacea. 



Bemains of Cetacea are tolerably abundant in Tertiary 

 deposits, both in Europe and North America. In the Lower 

 Pliocene of England, France, and Germany, extinct species of 

 five or six living genera of whales and dolphins have been 

 found ; and most of these occur also in the Upper Miocene, along 

 with many others, referred to about a dozen extinct genera. 



In the Post-pliocene deposits of Vermont and South Carolina, 

 several extinct species have been found belonging to living genera; 

 but in the Miocene deposits of the Eastern United States ceta- 

 cean remains are much more abundant, more than 30 species of 



