xi. CETEOSAURUS. 255 



cases the opposite sides have been forced into interference ; occa- 

 sionally the pressure has been endways, and the bone has become 

 fimbriated or spread out like a fungus to more than its original 

 diameter. The processes are generally broken off, and the frag- 

 ments, probably by carelessness of the workmen, have been so 

 confused and injured, that only one anterior dorsal vertebra has 

 been reconstructed, and it is imperfect in the lower part. 



This vertebra is represented in Diagram LXXXVI. 



The dorsal vertebrae of our ceteosaurus are not constructed on the 

 crocodilian type, except in their bearing double-headed ribs. The 

 body is contracted in the middle, and deeply impressed under the 

 rib-bearing process. The articulating faces are nearly circular, 

 one concave, the other convex, but the crushed state in which 

 they occur renders it often difficult to say which is anterior. In the 

 specimen represented above the anterior face is convex, the posterior 

 concave, but the outline of the body is incomplete and deficient 

 of the whole border n . 



The diapophyses are strongly carinated, and directed upwards 

 and outwards, so that if prolonged downwards they would meet 

 centrally at a right angle ; the neural spine, a broad vertical mass, 

 is expanded laterally, and finishes in a thick massive subquadrate 

 head, instead of forming a thin longitudinal blade, as in crocodiles. 

 In these massive processes are cavities of considerable size ; and 

 in the angular shape of the bones, and a sort of buttressing ob- 

 servable in the arrangement, we seem to behold a structure of 

 as much lightness as could be consistent with the required 

 solidity. 



The articulation of one vertebra with another is quite unlike 

 in different parts of the vertebral series, and even in the dorsal 

 series itself. The vertebra shewn is a forward dorsal, the para- 

 pophysis not being borne on the lateral spine. The zygapophysis 

 appears to form a large concave sweep above, buttressed below at 

 each end, and supported in the middle by a vertical ridge, which 



n Streptospondylus. Professor Owen mentions (Eeport on Eeptiles, 1841, p. 88) 

 a vertebra of this genus, or rather the anterior half of one, as being in the collection 

 of Mr. Kingdon of Chipping-Norton, and found in the oolite near that town. It is 

 an anterior dorsal, convex in front, with a deep lateral pit behind each of the costal 

 articular surfaces : a portion of a spinous process, rugged and quadrilateral at the 

 summit, accompanied the vertebra. This description seems to correspond to the 

 anterior dorsals of our ceteosaurus from Enslow "Rocks. 



