77 



gate conic crowns, which arc minutely but sharply striate to the tip; the 

 ridges straight, continuous. There are no indications of nostrils, so that these 

 were probably posterior, and near the orbits, as in Plesiosaurus. 



The pelvic arch is more extended than the scaj)ular, and strongly re- 

 sembles the pelvic arch of the Fksiosauridcc. The scapular arch is peculiar ; 

 the claviculi are broad, flat bones, resembling the pubes of certain tortoises, 

 while the coracoids are much like the coracoids of Plesiosaurus. The clav- 

 icles have a greater transverse extent than the latter, and have a very exten- 

 sive line of union medially, and a narrow posterior prolongation, which meets 

 a similar anterior one of the coracoids, separating the intervening foramina. 

 They appear to form about one-third of the walls of the glenoid cavity, and 

 have a constricted base, as in some riesiosauria, applied to the extremity of 

 the coracoid. The form of the glenoid cavity cannot be readily ascertained 

 from the absence of the scapula. What we have of it would suggest the ex- 

 istence of a fore-limb, of comparatively little power, though no remains of such 

 have been found. The acetabulum is smaller than the glenoid cavity ; this 

 point, with the obvious source of propulsive power in the tail, indicates that 

 the hind limbs were smaller than the fore. There is no trace of sacrum, nor 

 of any modified diapophyses for support of an ilium. 



The ischia are flat, subtriangular bones, with a long median line of junc- 

 tion, and communicating anteriorly with the posterior prolongation of the 

 pubic plate. Their postero-exterior margins project well backward. The 

 pubes are broad plates, whose anterior margins diverge from each other. 

 They are broader than the ischia, and form a broad, shallow basin for the 

 support of the viscera. The suture defining these elements is obliterated ; 

 they are continuous, and form a weak, inferior keel on the median line. A 

 simple curved ilium has been preserved, for which there appears to be a 

 smooth articular surface on the pubis, to which it was attached. 



The acetabular portions of these elements are flattened and furnished 

 with convex articular surfiiccs. The supposed ilia are short, curved bones, 

 resembling that of Plesiosaurus latispinus, Ow., or of some of the other spe- 

 cies of that family. The shank is flattened cylindric ; the distal extremity 

 dilated, rounded, and flattened ; the proximal extremity subtruncate, or trun- 

 cate in two or three unequal planes, and witli a median pit. It fits well 

 when applied to a concavity on the articular surface of the pul)is. Tiie ver- 



