152 



THE OSTEOLOGY OF THE REPTILES 



The ilium is firmly connected with the sacrum, and there is a pubic 

 foramen; the pubo-ischiatic notch is small. In the Plesiosauria (Figs. 



Fig. 125. Pelvic girdle of Trinacromerum osborni, an Upper Cretaceous plesiosaur, 

 from above: />, pubis; is, ischium; //, ilium. 



125, 126), the slender ihum, connected ligamentously with a sacrum 

 of three or four vertebrae, articulates at its distal extremity with the 



