SAURO PTERYGIA 



8i 



quite certain because_of the very broad expanse of the coracoids, 

 between tin- articulations of the front legs. 



The shoulder girdle or pectoral arch is strangely unlike that of 

 any other reptiles. There is no breast bone, since the breast bone 



Fig. 35. — Pectoral girdle of Tr'ntacromcrum from above: ic, interclavicle; d, 

 clavicle; sc, scapula; c, coracoid. 



is a comparatively late development in reptiles, not appearing, 

 probably, until after the plesiosaurs had begun their existence. 

 Taking the place of the sternum, the very large and broad coracoids 



