7. DIOPLODON. 355 



are sufficient to clearly characterize the species. Unfortunately the 

 last-mentioned peculiarity is scarcely sufficiently indicated in the 

 figure. 



The edges of the front lower teeth are absorbed or worn away by 

 the fi'iction of the upper jaw against them, the vomer forming a 

 large fusiform prominence on the upper surface of the base of the 

 beak, in front of the blowers, between the narrowed part of the 

 elongate, slender intermaxillarieSj which are enlarged and thickened 

 behind, forming the outer sides of the blowers. 



In this respect it agrees with the figure of the skull of Dioplodon 

 Sechellensis from the Indian Seas, given by M. Gervais (Zool. et 

 Paleont. rran9. t. 40. f. 3-6) ; but the vomer is more prominent in 

 the Cape species. The Cape species has the slender, elongated, 

 tapering lower jaws, and a very much longer beak to the skull, like 

 that of D. microptenis of Havre (Gervais, I. c. t. 49. f. 1). 



I was informed, in 1864, that two Dolphins which agreed with 

 M. F. Cuvier's description and figure of Delphinorhynclms micropterus 

 had been taken on the coast of South Africa, and that the skulls were 

 then in the possession of a surgeon at the Cape. There is also a 

 third skull, in a semifossil state, in the colony. 



7. DIOPLODON. 



Lower jaw broad behind, suddenly narrowed in front before the 

 teeth. Teeth in the side of the lower jaw (of male ?), large, com- 

 pressed, considerably behind the back edge of the rather short 

 symphysis. 



Animal unknown. 



Dioplodon (part), Gervais, Zool. et Paleont. Franq. 



Dioplodon, Gray, Proc. Zool. Soc. 1863, 200. 



Mesiodon (part), Duvernoy, Ann. Set. Nat. xv. 58. t. 2. f. 4. 



Dioplodon Sechellensis. The Seychellc Ziphius. 



Ziphius de Seychelles (M. le Due, 1839), Mus. Paris. 



Ziphius Sechellensis, Gray, Zool. E. c^ T. 28. t. 6. f. 1, 2 (lower jaw). 



Ziphius densirostris, Slainv. Mus. Paris. 



Mesodiodon densirostris, Duvernoy, Ann. Sci. Nat. 1851, xv. 58. t. 2. 



f. 4 (not D. densirostris, Desm.). 

 Dioplodon densirostris, Gervais, Zool. et Paleont. Franq. t. 40. f. 3-6 



(skull) ; Gray, Proc. Zool. Soc. 1863, 200. 



Inhab. Seychelles. Skull in Mus. Paris. 



The skull is very like that of Zijihius, but the nose-bones are 

 thicker, heavier, and higher. The teeth in the middle of the lower 

 jaw, as in the male Z. Soiverhiensis, but larger and compressed. The 

 hinder part of the lower jaw is very broad, the front half much nar- 

 rower and bent down in an arched manner. 



2 a2 



