Hi 



MAE1NE EEPTILES OF THE OXFORD CLAY. 



border. The acetabular border is smootb, with the acetabular surface opposite the 

 posterior union with the ischium running well up on to the outer face of the bone ; 

 from this surface the articulations for the upper end of the anterior process of the 

 ischium and for the upper end of the pubis are separated by a notch, and form a broad 

 smooth area above the anterior part of the acetabular border extending to the antero- 

 ventral angle. The surface for union with the ischium is much roughened, and there 

 seems to be no doubt that in front of it there is a surface for independent union with 

 the upper end of the pubis. The inner face of the ilium (text-fig. 72) is convex : 

 towards its upper border it bears two surfaces (sac.s.l., sac.s.2.) for union with the 



Text-fis. 71. 



Outer side of left half of pelvis of Ifetriorhynchus moreli. (R. 2054, ^ nat. size.) 



(7.(i., anterior angle of ilium ; acet, acetabulum ; a.p.i., anterior process of ischium ; il., ilium; 



is., ischium ; pu., pubis. 



outer ends of the sacral ribs ; the upper part of the surface for the first sacral forms 

 a deep fossa beneath the dorsal border. The surface for the second sacral rib 

 extends nearly down to the postero-inferior angle. 



The ischium (is., text-figs. 71, 72) in its general form is much like that of 

 Steneosaurus, the chief difference being in the relatively rather smaller size of its 

 anterior process. Ventrally the broad expanded blade bears a slightly curved oblique 

 sutural surface [sym.is.) for union with its fellow. The neck is less sharply defined 

 than in Steneosaurus, the bone narrowing gradually to just below the proximal 

 articulation, which bears a surface for union with the posterior portion of the ventral 



