and Clavicular Arch in Sauropterygia. 



129 



contours of the clavicle are irregularly concave, and as they extern d 

 inward are continuous with the posterior border of the interclavicle, 



Tigs. 2 and 3. — Ventral and visceral aspects of clavicular arch of Plesiosaurus 

 arcuatus, showing the median interclavicle and lateral clavicles. Ic is 

 placed on the anterior margin. 



