214 



PKOF. H. Gr. SEELEY ON HETEROSUCHUS VALDENSIS 



inferior margin of the cup is in every case worn, the obliquity appears 

 greater than it was in life. Each centrum is -about 19 millim. long ; 

 the articular ball is well rounded. The form of the centrum is 

 compressed from side to side below, with the base rounded. The 

 sides are concave, without any thickening of the bone in the position 

 where the neurocentral suture is usually present. The transverse 

 processes are broken, but enough remains to show that the usual 

 posterior concave incision existed between the transverse process 

 and the postzygapophysis. Prom the hinder margin of the transverse 

 process a sharp ridge descends in a concave curve as it extends 

 backward to the outer border of the articular ball. Posterior 

 to this ridge the bone of the neural arch is impressed, and ascends 

 to the postzygapophysis. The underside of the transverse process 

 (fig. 8, t) which was compressed from above downward in the usual 

 way, appears to have been convex at its base. Prom both the anterior 

 and posterior zygapophyses well-defined compressed rounded ridges 

 ascend and converge, as they extend inward towards the neural 

 spine. Between these ridges is a concave recess with a flat base, 

 forming the inward termination of the upperside of the transverse 

 process. The height from the base of the centrum to the transverse 

 process is greater in the anterior vertebrae of the series than in 

 the later ones. In the third it is 15 millim. ; towards the end it is 

 scarcely more than a centimetre. The neural spines are well 

 developed; they ascend vertically in the anterior vertebra and 

 are inclined slightly forward in the later ones. The height from the 

 base of the centrum to the summit of the neural spine is about 33 

 millim. The spine widens a little towards its summit, which is 

 convex from front to back ; its anterior and posterior margins 

 are slightly concave. 



A lumbar centrum is present, and exhibits a rather narrow neural 

 canal. 



The sacral vertebras are imperfectly preserved; there were 

 probably two. From the second the transverse processes are 

 completely lost, but the first shows these processes to have been 

 quadrate and strong. As in existing Crocodiles, they are concave in 

 front, flattened above, and, as they extend outward, depressed below 

 the prezygapophyses. The transverse measurement across the 

 processes, as preserved, is 25 millim. 



The vertebral characters described show divergences from existing 

 Crocodilia, such as on the whole are approximations towards Dino- 

 saurian types of Wealden age, a condition of more interest from 

 the Crocodiles of the Gosau beds having shown some approxima- 

 tions in vertebral characters to the Gosau Dinosaurs. 



A few isolated vertebrae of similar character were collected by 

 Dr. Mantell, from Tilgate, and from Brook in the Isle of Wight. A 

 small caudal vertebra from Tilgate has the base of the centrum 

 compressed from side to side and rounded, with a concave impression 

 above the middle of the side, immediately beneath the transverse 

 process. The prezygapophysis is long and directed upward and 

 outward. The articular cup is perfectly circular. The centrum is 



