NEOCOMTAN EOCKS OF COMEX, iSTEAE TEIESTE. 



53 



only pelvic element clearly exhibited ; and that is directed backward in 

 the usual lacertian manner (fig. 1, i). The hind limbs are preserved, 

 though they were fast becoming obliterated by weathering. The caudal 

 vertebrae lie upon one side, and consequently do not give a very dis- 

 tinct idea of their forms. They, however, show no trace whatever 

 of the neural spine, though the chevron bones are well developed, 

 and are preserved down the greater part of the tail. The dorsal 

 vertebree apparently rest upon the neural surface and expose the 

 visceral surface. This may be inferred from the form of the cen- 

 trum, the curvature of the ribs, which are concave in length as 

 exposed, and the fact that the ilium underlies the femur ; but the 

 face of each centrum has been somewhat dissolved, so that it cannot 

 in any case be said to exhibit the unaltered appearance of the bones. 

 Each centrum in the dorsal region is rather less than ^ a centim. 

 in length, and is about 6 millims. wide in front. The sides converge 

 posteriorly to about 3 millims. ; so that, besides being a far smaller 

 animal, the lower dorsal vertebrae appear here to be relatively 

 shorter, and the centrum, instead of having the concave lateral 

 outlines of Hydrosaurus, has its side rather convex in length; 

 and the anterior surfaces on each side of the anterior articulation 

 look more forward and less outward than in that genus. There 

 is, moreover, no ] indication of the transversely concave outline of 

 the intervertebral union — but in place of it a notch in the ante- 

 rior border, as though there were a small ossicle at the junction of 

 each two vertebrae ; but this apparent notch may be nothing but 

 the neural canal exposed in this position by the thin base of the 

 centrum being there dissolved. As the vertebrae pass downward 

 towards the sacrum, their aspect seems to be less massive, and the 

 posterior end becomes a little more compressed from side to side. 

 There are slight indications of two ridges running longitudinally 

 on the base of the centrum from the outer corners of the anterior 

 •cup towards the posterior articular ball. All the dorsal vertebrae 

 were furnished with ribs ; but they become shorter and smaller 

 towards the sacrum. On the right side of the specimen they lie 

 together, touching each other along their lengths, except in the case 

 of the last three or four, which are only indicated by impressions. 

 The ribs appear to be flat on the under side and moderately curved ; 

 the rib of the third vertebra preserved is 2 centims. long and 2 

 millims. wide at the proximal end. The ribs appear to be tubular 

 and single-headed ; they taper evenly to a blunt point, but scarcely 

 give the impression of being relatively so stout as the ribs of Hydro- 

 saurus. The sacral vertebrae are no better defined than those of the 

 dorsal region, being partly covered by femoral bones. There is an 

 angular bend in the tail, beyond which the vertebrae lie on their 

 sides more perfectly displayed than in the case of the first few caudals. 

 The neural arches of the caudal vertebrae were low, without any indi- 

 cation of neural spines, the neural arch being concave superiorly from 

 front to back, and articulating with the arches of adjacent vertebrae 

 by zygapophyses, which were elevated high above the neural sur- 

 face. The neural arch widens in front, and is smooth at the sides. 



