GENUS PRODELPHINUS, 



Table of measurements — Coutiuued. 



61 



5. PEODELPHINUS Gervais. 



ProdclphliiKs, Gervais, Ost(5og. des C(5tac6s, 1860, p. 604. 



Tliis genus is closely allied to Belphinus aiitl Tursiops. The cliief 

 cliaracter wbicb has been brought forward as separating it from Del- 

 phinus is a negative one — the absence of deep lateral palatine grooves. 

 From Tursiops it is distinguished by its smaller and less numerous teeth 

 and (generally) more numerous vertebra;. These latter characters, it 

 nuist be confessed, are not very trenchant, and it may be found neces- 

 sary at a later day to unite Froddphhius with Tursiops. 



The genus comprises a large number of nominal species, for the most 

 ])art founded upon single skulls. Nearly every large collection contains 

 a considerable number of skulls which may be assigned to this genus. 

 It is found, however, in many cases that when a large number of these 

 skulls is brought together they tend to form continuous series. The 

 difterences between the extremes of these series are often striking and 

 perfectly definable, but in the middle they melt away and elude deti- 

 iiition. From this fact and from the absence of material the task of 

 revising the species of this genus is a very difficult and disheartening 

 one. Professor Flower has, however, led the waj" (in the Characters 

 and Divisions and also in the List) to a better knowledge of the group, 

 and in his opinions I for the most part concur. 



In the succeeding ])ages I shall consider about 23 species which 

 appear to me to belong to this genus, including some which have not 

 been touched upon by Professor Flower. I bring together the names 

 of all these species in the following table: 



Prodclpbiuns ccprnleo-albu.s (Meyen). 

 euphrosyne (Gray). 

 Styx (Gray), 

 euplirosynoides (Gray). 



Prodclpliinus dorides (Gray). 



tetbyos (Gervais). 

 marginatas (Diivernoy). 

 dubius (Cnvier). 



