6 PEOFESSOB FLOWEE ON EISSO'S DOLPHIN. 



inches. 



Length of inferior surface of conjoined bodies 2-4 



Length of conjoined arches "'^ 



Height from inferior surface of atlas to apex of conjoined spinous 



5-4 

 processes ^ ^ 



Breadth of articular surfaces of atlas 4- / 



Breadth between tips of transverse processes of atlas 7-7 



Breadth between tips of transverse processes of axis 5-3 



Breadth between tips of transverse processes of seventh vertebra . .5-2 



Greatest breadth of simial canal (inside arch of atlas) 2-0 



Height of spinal canal at the same place 1"4 



The thoracic vertebi-ae are twelve in number. The body of the first is but 0-6 of an 

 inch in length ; they gradually increase from this to the fifth ; but the remainder are 

 very nearly equal, viz. 1-7 inch in length, and present no marked differences in breadth 

 and height. Articular surfaces for the heads of the ribs are developed on the hinder 

 edge of the base of the pedicle of the arch of the first five ; and on the sixth there is a 

 rough tubercle in the corresponding position. The spine of the first is very small and 

 directed forwards ; that of the second is equally low, but broader in the antero-posterior 

 direction; that of the third is long and pointed, and sloping much backwards; the 

 remainder increase gradually in length to the last, and become more upright in position ; 

 beyond the sixth they have a slight forward curve. The transverse processes arise in the 

 anterior vertebrae high up on the sides of the arch ; but, as in other true Dolphins, their 

 position is gradually lowered until, before the termination of the thoracic region, they 

 are transferred to the bodies of the vertebrae. In the first seven vertebrae they are of 

 nearly equal length, but from the eighth to the twelfth they gradually increase. They 

 all have articular surfaces at their extremities for the heads of the ribs, at first oval 

 from above downwards, but gradually becoming elongated in the other direction. In 

 the twelfth the surface is convex and very slightly marked. Zygapophyses are deve- 

 loped only as far as the articulation between the sixth and seventh. The metapophysial 

 tubercles are slightly indicated on the third, near the outer end of the anterior edge of 

 the transverse process ; on the sixth and seventh they are prominent, conical, and close 

 to the base of the process ; on the eighth they become less marked, and begin to rise 

 on the side of the arch ; and they no longer exist as distinct processes on the eleventh, 

 and thenceforth are only indicated by a slight bulging forwards of the anterior edge of 

 the upper part of the arch, and do not reappear, as is usually the case, in the lumbar or 

 caudal region'. 



The bodies of all the lumbar vertebrae are very nearly equal in length, viz. 1"4 incli. 



' The metapophyses of the posterior thoracic region are much better developed in the skeleton of the 

 " Grampus rissoanus," figured by Van Beneden and Gervais (op. cit. pi. 54. fig. 1), than in the present 

 specimen. 



