1236 THE CETACEANS 



dolphin, which is figured in the accompanying illustration, has the upper parts and 

 flukes yellowish white, and the under parts and flippers white. A notice of some of 

 the habits of the tucuxi has been given above on p. 39. 



Another representative of this group is the Chinese white dolphin 

 (S. sinensis], from Quetnoy island, in the harbor of Amoy, and the 

 Foo-Choo and Canton rivers. It is said to be characterized by its gen- 

 eral milk-white color, pinkish fins, and black eyes. 



The most interesting member of this group is, however, the recently 



D . ,. described Cameroon dolphin (S. teuzsi] from the estuaries and rivers of 



the Cameroon district of Western Africa which is reported to be of 



herbivorous habit. If this alleged habit should be confirmed, this dolphin will 



THE PAI,E, RIVER DOLPHIN. 



(From True, bulletin of the U. S. National Museum, 1889.) 



differ not only from all the other members of the family to which it belongs, but 

 likewise from all other living Cataceans. 



SQUALODONTS AND ZEUGLODONTS 

 Families S^UALODONTID^ and ZEUGLODONTID^E 



In addition to numerous extinct representatives of the existing Cetacean 

 families, to some of which reference has been made above, there are two extinct 

 groups which cannot be included in either of the existing families; one of these 

 differing very much indeed from all modern Cetaceans. 



The name of squalodouts (genus Squalodori) is applied to the mem- 

 bers of the first of these two groups on account of the somewhat 

 shark-like structure of their cheek-teeth. In the general characteristics of their 

 skulls these Cetaceans approximate to the modern dolphins, from which they are, 

 however, at once distinguished by the teeth being of different characteristicts in 

 different parts of the jaws, as in ordinary Mammals. They have a total of fifteen 

 teeth on each side of both the upper and lower jaws. Of these the first four are of 

 simple structure, and correspond to the incisors and canines of other Mammals; the 

 next four, which are also comparatively simple, appear to represent the premolars; 

 while the last seven have two roots, and latterally-compressed triangular crowns, 

 with sharp-cutting edges, upon which there are a number of cusps arranged in a 



