REVIEW OF THE SPECIES OF DOLPHINS. 



Subfamily I. DELPHIKIN^. 



1. SOT ALIA Gray. 



Sotalia, Gray, Cat. Seals and Whales, Brit. Mus., 2d ed., 18GG, p. 401; Synopsis, 

 1868, p. 6 ; Supplement, 1871, p. 67. 



The type of tbis genus is the Delphinus guianensis of Van Benedeu. 



Of the characters assigned to the genus l)y Gray (1. c.) and by Pro- 

 fessor Flower (Characters and Divisions, p. 513) only three seem to me of 

 real value as distinguishing itfrom Tursiopsand Steno. These are (1) the 

 separation of the pterygoids; (2) the more limited number of the caudal 

 vertebra? ; and (3) the greater number of teeth. The somewhat unusual 

 breadth of the base of the pectoral fin is shared by Steno. The unusual 

 length of the symphysis of the mandible which has also been cited as 

 a generic character seems to me of little value, since it is not shared bj^ 

 all the species. Although in 8. i^lumheus, Icntiginosus, and smensis the 

 symphysis occupies about one-third of the ramus of the mandible, in S. 

 iucnxi and gadamu it occupies onl^' about one-fifth. 



The genus, as already intimated, is very closely related to Steno and 

 Tursiops, both in its external form and its osteology. It shows some 

 relationship, however, to Plata7iista, Inia, and Fonioporia in the com- 

 paratively small number of its vertebrsB and the length of their centra. 



It will be necessary for me to treat of the species with much reserve 

 since I did not have the opportunity of examining carefully all the types 

 and must therefore base my opinions partly upon the descriptions and 

 drawings which have hitherto been published. 



SOTALIA GADAMU (Owen). 



Delphinus (Steno) gadamu, Owen, Traus. Zool. Soc. London, vi, 1866, p. 17, pi, 



III, figs. 1-2. 

 Sotalia gad a v Flower, Proc. Zool. Soc. Loudon, 1883, pp. 489 and 513. 



This species is the first treated of in Sir Eichard Owen's memoir upon 

 the Indian cetacea. His material consisted of drawings and a defective 

 skull (1477Z>) which is now in the British Museum. The mandible which 



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