102 



5. DI0PL0D0N. 



Dioplodon, Gray, I. c. pp. 327, 355 ; Synops. Whales fy Dolph. p. 10. 

 Teeth 2 or 4, conical, in the middle of the sides of the lower jaw. 

 Lower jaw broad behind, suddenly contracted in front. Symphysis 

 moderate, not reaching halfway to the teeth. 



1. Dioplodon sechellensis. 



Ziphius sechellensis, Gray, Syiiops. Whales fy Dolph. t. 6. f. 1, 2 



(skull). 

 Dioplodon sechellensis, Gray, Cat. S. fy W. p. 355 ; Synops. Whales 



Sf Dolph. p. 10, t. 5. f. 4 ; Ann. Sf Mag. N. H. 1870, vi. p. 343, fig. 



(skeleton) ; Gervais, Osteog. Cet. t. 25 (skull). 

 Dioplodon densirostris, Gervais, Zool. Paleont. Franq. t. 43. f. 3-6. 



Inhab. Seychelles. Mus. Paris. Lord Howe's Island (Krefft). 



The form of the lower jaw gives a very peculiar appearance to 

 the skeleton. The cervical vertebras are united together by their 

 bodies and large dorsal spines, the latter forming a thick conical 

 process. The bodies of the dorsal vertebrae are very small, en- 

 larging in size towards the tail ; they are thirty-six in number. 

 The four terminal caudal ones are very small, forming a kind 

 of cylindrical process. There are eight chevron bones. The tho- 

 racic cavity is small. There are twelve ribs on each side. The 

 dorsal processes of the first eighteen vertebras have an anterior basal 

 process, which becomes gradually smaller. 



Upper arm-bone ver) 7 slender, slightly curved ; the lower arm- 

 bones moderate, straight, parallel to each other, and rather longer 

 than the upper arm-bone. The ribs very broad at the upper end, 

 and gradually tapering towards the chest, where they are nearly 

 cylindrical. 



" The total length of the skeleton, without cartilage, is 14 feet 

 8 inches ; the head measures 2 feet 5-^ inches in length, and the 

 lower jaw 2 feet 3 inches in length. The first three cervical ver- 

 tebras are anchylosed ; the next one is more or less free ; and the 

 remaining three are anchylosed again. The dorsals are ten in 

 number, the last bearing a short rib 8 inches in length. Five of 

 these ribs are jointed direct to the sternum ; the following two meet 

 the cartilage of the fifth rib. 



" The sternum is composed of four pieces, 20 incbes long, with a 

 width of between 5 and 7 inches. It is not yet sufficiently cleaned 

 to enable me to have it photographed ; this, however, will be done as 

 soon as possible, and copies forwarded to the Society. The lumbars 

 number twenty, the last nine having V-bones attached. The fifth 

 lumbar is 17^ inches high, 4 inches wide at the top, and llf inches 

 at the base, including the side processes. The eleventh lumbar is 

 the widest, being 4| inches at the top. The caudals probably 

 amounted to 13 ; but five of these are missing ; the basal one is very 

 small, about the size of a pea ; and as it was firmly attached to the 

 second last, there can be no mistake about it. 



