Apr. 1903. North American Plesiosaurs — WfLusTON. 



49 



the cartilage continued to the rounded outer anterior angle, where 

 the bone is a little more thickened. The acetabular surface is much 

 the larger of the articulating facets. It meets the smaller and rough- 

 ened facet for the ischium in a very obtuse angle. The bone is more 

 thickened on the outer and posterior parts, that is, near the non- 

 cartilaginous border, than elsewhere. (See PI. XVI.) 



Fig. 12. 



Diagram of pelvic girdle of Delichorhynckops estemi, visceral surface. I'n.. pubis; ist, ischium; 

 ;/.. ilium. < 



The ischium is more elongate and proportionally larger than is 

 usual among plesiosaurs, though of the usual hatchet shape. It has 

 three hon-sutural articular surfaces — the larger middle one, looking 

 directly outward in the articulated ischium; a smaller posterior one, 



