Type of the Genua Masso.spondylus. 105 



side, and moderately elevated long parapophysial facets for 

 the rib, below the middle of the sides of the anterior face 

 for the centriun. The body of the vertebra is 4y=V inches long 

 at the ba^e and hardly more than 4 inches long at the neural 

 canal, showing that the cervical vertel)ra3 were carried in a 

 curve which was convex on the anterior or ventral surface, 

 from which it follows that the neek was elevated. The ante- 

 rior face of the centrum is slightly distorted, but appears to 

 have been circular, T,V inch in diameter. The surface 

 aj)pears to have been concave and bordered by a sharp margin, 

 but it is imperfectly excavated. At the base of the articular 

 surface is an ajipearance as tiiough there may have been a 

 narrow, thin, intercentral ossification, not unlike that seen in 

 Pareiasaurus. A somewhat similar bevelling, which I should 

 attribute to a like cause, is seen below the posterior articular 

 margin, and may account for the original identification of the 

 vertebra as caudal. The posterior end of the centrum is 

 rather larger. A sharp, straight, median ventral ridge extends 

 concavely from front to back along the base. The sides of 

 the centrum are greatly constricted and consist of inferior 

 portions, which converge downward from the lower articula- 

 tion for the rib, and superior ])ortions, which are nearly 

 vertical and ])arallel. The centrum is thus constricted in the 

 middle to less than half its width at the ends. This con- 

 striction or excavation is greatest below the transverse process, 

 which is given ofi'just above the neuro-central suture. That 

 process has a long base, is directfd outward and a little down- 

 ward ; it is compressed from above downward, is slightly 

 convex above and rather concave below. There is no evidence 

 of a pneumatic foramen on its underside. 



The neural arch, in harmony with the slender centrum, is 

 chiefly remarkable for the low truncated neural spine and 

 strong cleft divergent zygapophyses. Seen from above the 

 anterior and posterior ridges of tlie zygapophyses approximate 

 almost in the form of a ca])ital X, owing to the lateral trans- 

 verse constriction above the transverse processes being similar 

 to that of the centrum. The neural spine is lj*o inch above 

 the zygapophysial ridge ; its vertical anterior border is in a 

 line with the middh- of the transverse process. Superiorly 

 it is gently convex frum front to back. Its short posterior 

 border is rather in advance of the slight notch for the inter- 

 vertebral nerve. From the base of the neural spine the 

 zygapophyses diverge as compressed wedge-shaped processes, 

 sejjarated throughout their length, with the articular facets 

 inclined, so that the anterior pair look inward and upward. 

 These facets are slightly convex. The process is concave on 



