xm. PLESIOSAURUS. 375 



Cervicals. The articulating faces elliptical, plane, pitted in the 



Diagram CLXX V. Plesiosaurus carinatus. Scale one-fifth of nature. 

 Cervical vertebra, seen from below (upper figure), and from above (lower figure). 



centre ; the foramina on the lower face approximate, with a pro- 

 minent narrow ridge between them. 



Length, 1-63 inches; breadth, 1*95; height, 1*60: or, length, 

 100; breadth, 120; height, 98. 



In the anterior dorsals the interforaminal space remains ridged ; 

 they are shorter than the cervicals. 



Length, 1-45 inches ; breadth, 2*00 ; height, i'64. 



In the dorsals the interforaminal ridge is gradually lost. 



Length, 1-40 inches ; breadth, i'8o; height, 1*60. 



One lumbar vertebra is in the collection. 



PLESIOSAUKUS HEXAGONALIS. n.s. PhU. 



A small caudal vertebra from the Cowley clay pits, of somewhat 

 remarkable figure, deserves mention for its almost hexahedral shape, 

 the broad semicylindrical neural canal making one side. The 



Diagram CLXX VI. Caudal of a Plesiosaur. Scale one-fifth of nature. 



articulating faces are equally concave, much wider than high ; there 

 are two medial and two lateral foramina, and the cicatrices for the 



