504 PROF. VLOWER ON THE DELPHINID^. [j^O^- 20, 



Gervais in the ' Osteograpliie des Cetaces,' pi. xxxix. figs. 10 and 11. 

 The specimen is from the Malabar coast, and marked " Dussumier, 

 1827," but does not appear to have been described until the publica- 

 tion of the ' Osteographie.' It is certainly not the D. longirostris of 

 Gray's ' Spicilegia,' p. 1 (1828), described from a skull now in the 

 Leiden Museum, as that has fewer teeth and no grooves on the palate, 

 and is therefore not a true Belpkinus, although, as said above. Gray 

 in his Catalogue and Synopsis places it at the head of the section of 

 Dolphins characteiized by the " Palate with a deep groove on each 

 side," and joins the Paris specimen with it in his account of the species. 



It may be convenient to append a Synopsis of the principal charac- 

 ters of the divisions of the whole family, which appear to me of 

 generic value, with some remarks upon the best-known species. 

 This will serve to show what are the natural groups into which the 

 different members of which it is composed appear, according to our 

 present knowledge, to resolve themselves, although in endeavouring 

 to set it out, the usual difficulty has occurred in arranging in a 

 linear series a number of forms the affinities of which are so closely 

 intertwined. Although the most nearly allied have been brought to- 

 gether when possible, this cannot always be done in such a list. 

 The arrangement must therefore be considered to a certain extent 

 arbitrary, and subject to modification according to the judgment of 

 different zoologists. Even in the primary grouping together of the 

 Dolphins with rounded heads and those with projecting beaks I have 

 probably followed loo much the traditional and artificial order, 

 instead of finding one more consonant with natural affinities. 



We must wait until our Museums are more abundantly supplied 

 with specimens before it will be possible to attempt with any success 

 a complete and critical examination of the minor modifications which 

 we commonly call specific. 



Synopsis of the Genera of DelphiniDjE. 



A. With rounded head, without distinct rostrum or beak. In the 

 skull the rostrum is about equal in length to the cranial portion. 



a. The first and second cervical vertebras not united. 



MoNODON, Linnaeus, Syst. Nat. ed. 12, i. p. 10.5 (176()). 



Pterygoid bones very small, not meeting in the middle line, ap- 

 proaching each other posteriorly as in Lelphinaptei'us (see fig. 3, 

 p. 472). Dentition reduced to a single pair of teeth, which 

 lie horizontally in the maxillfp, and which in the female remain 

 permanently concealed in the alveolus, while in the male the 

 right tooth usually remains similarly concealed and abortive and 

 the left is immensely developed, attaining a length equal to more 

 than half that of the entire animal. Vertebrae : C. 7, D. 11, L. 6, 

 C. 26 ; total 50 '. Cervical region comparatively long, and all the 



' The numbers of the vei-tebra? and of the teeth given in tliis synopsis are 

 averages, subject to shght individual modifications. 



