GENUH riiOJJELPHlNUS. 



Table of meafiiiremeiits — Contiuned. 



61 



5. PEODELPHINUS Gervais. 



Prodclphinus, Gervais, Ost6og. cles Cctac6s, 18S0, p. 604. 



Tliis genus is closely allied to Delphimis and Tursiops. The chief 

 cliaracter wliicU lias been bronglit forward as separating it from Dcl- 

 phinus is a negative one — the ab.sence of deep lateral i)a]atiue grooves. 

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

 and (generally) more numerous vertebrae. These latter character.^, it 

 must be confessed, are not very trenchant, and it may be fouud neces- 

 fc-ary at a later day to nnite rrodclphhins 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 siaiUs which may be assigned to this genus. 

 It is fouud, hosTcver, in many cases that when a large num])er of these 

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

 differences between the extremes of these series are often striking and 

 l)erfectly definable, but in the middle they melt away and elude defi- 

 nition. 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 way (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 i)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 

 (>r all these species in the following table: 



Proddphirjus caTixleo-albus (Meyen). 

 cnphrosyue (Gray). 

 Styx (Gray), 

 euplirosynoides (Gray). 



Prodt'li)liiiuis dorides (Gray). 



tetliyos (Gervais). 

 margiiiatus (Dnvernoy). 

 dubius (Ciivier). 



