452 



reappears in the caudal vertebra at the fore-part of the base of the spine*. The six anterior 

 pairs of ribs support hsemapophyses which unite directly with the sternum. 



Presented by Sir Everard Home, Bart., V.P.M.S. 



2490. The anterior portion of the upper jaw of a Dolphin (Delphinus delphis). It 

 includes 31 teeth : the external alveolar wall has been removed, and a vertical 

 section of the roots of the teeth has been made to expose their pulp-cavities. 



Hunterian. 



2491. The skull of a Dolphin (Delphinus delphis). 



Number of alveoli : ^~ = 1 73. 



Hunterian. 



2492. The skull of a Dolphin (Delphinus delphis), wanting the lower jaw. 



Alveoli of the upper jaw : 49 5 1 . 



Hunterian. 



2493. The skull of a Dolphin (Delphinus delphis}. 



Hunterian. 



Number of alveoli : *~= 186. 



2494. The skull of a Dolphin (DelpMnus dubius, Cuv.). 



4040 



Alveoli of jaws : ^=160. 



This skull differs from that of the Delphinus delphis, as Cuvier has observed, by the 

 appearance of the vomer in a longitudinal space on the palate, between the maxillaries and 

 premaxillaries : the palatal prominence formed by the palatine bones is broader and shorter, 



* There are no anapophyses in the Cetacea, and the metapophyses seem hitherto to have been over- 

 looked in this order. Cuvier, in his description of the vertebrae of the Dolphin, confounds them, as 

 Straus-Durckheim has done in the Cat, with the true zygapophyses. He writes, " The last cervical 

 and the first six dorsals have their articular processes joined together by horizontal facets, of which the 

 anterior looks upwards. At the sixth they begin to be oblique ; at the seventh they are nearly vertical, 

 the anterior looking inwards." But in the figure which he refers to, of the fourth dorsal vertebra of 

 the Delphinus delphis, the accurate artist, M. Laurillard, represents the metapophyses as distinct from 

 the prozygapophysis or anterior articular process, although less so than it is in nature ; and it is incon- 

 testably the progressive development of this superadded process which gives rise to the change of posi- 

 tion of the articular surface of the connate prozygapophysis : and the metapophysis continues to be 

 developed, as the figures in the ' Ossemens Fossiles ' demonstrate, long after the articular process or 

 any articular surface has ceased to exist (May 1845). 



