451 



2484. The skull of the Bottle-nose Dolphin (Delphinus tursio), wanting the lower 

 jaw. 



The number of alveoli in the upper jaw is: 23 24=47. The teeth are directed from 

 above obliquely downwards and forwards at a more acute angle than in younger specimens. 

 A great proportion of the crown is worn away in all except the last two or three, and a large 

 proportion of the unenamelled fang is exposed, upon which their more oblique position and 

 larger proportional size appear to depend. 



Mm. Brookes. 



248 5. The skull of an apparently aged specimen of the Delphinus tursio. 



All the teeth have been lost in this specimen, and the sockets are obliterated, except at the 

 anterior part of the alveolar tracts, where they are very shallow. This animal has been sub- 

 ject to some injury or disease of the jaws, which has occasioned an ulcerated surface in the 

 upper maxillary bone and in both rami of the lower jaw. 



Hunterian. 



2486. The skull of the Bottle-nose Dolphin (Defyhinus tursio). 



The number of alveoli in the jaws is : ^~^. 



Hunterian. 



2487. The petrotympanic bones of the Bottle-nose Dolphin (Delphinus tursio}. 



Hunterian. 



2488. The cervical vertebra? of the Bottle-nose Dolphin (Delphinus tursio'). The 

 atlas and axis have coalesced. Presented by Prof. Owen, F.E.S. 



2489. The skeleton of the common Dolphin (Delphinus delphis). 



The number of alveoli in the jaws is : J|^=182. Of the 7 cervical vertebrae the first 

 two have become anchylosed together : there are 63 other vertebrae, of which the first four- 

 teen bear moveable ribs, but it appears that a fifteenth pair of ribs is lost : thirty-four verte- 

 brae have transverse processes without ribs : the forty-second vertebra from the skull begins 

 to support heemapophyses : the eight terminal vertebrae consist of the centrum only, and are- 

 much flattened. The metapophysis begins abruptly, as a long well-marked process, from the 

 fore part of the diapophysis of the fourth dorsal, progressively approximates and attains the 

 outside of the prozygapophysis in the eighth dorsal, performs the function of an articular 

 process as far as the sixth lumbar, clamping, as it were, the sides of the back part of the base 

 of the spine of the antecedent vertebra, disappears in the next dozen lumbar vertebrae, and 



3 M 2 



