xin. PLESIOSAURUS. 371 



Allowing two for the anterior missing vertebrae, we shall have 

 in all, probably, twenty-eight unequivocal cervicals ; and perhaps 

 one or two more may have deserved to be classed in this category 

 rather than as anterior dorsals. 



Diagram CLXXI. Cervical vertebra of Plesiosaurus validus. 

 Seen on the left side and behind. 



These vertebrae have neatly bordered oval articulating fa^es, 

 equally concave, with rounded margins; the greatest breadth on 

 the anterior face being 3*85 inches; height, 3*10; length, 2*30. The 

 smallest specimen has a breadth of 1*60 inches; height, 1*30; length, 

 I 26. The neural canal is wide, very little contracted in the 

 middle ; the sides are impressed, the base pierced by two foramina 

 situated in depression, which separate more and more as we proceed 

 from the head. The neurapophyses, which are incomplete, rose 

 to about twice and a half the height of the body of the vertebra ; 

 the basal processes were short, broad, plane, and directed down- 

 ward. 



The length of the smallest (say 3rd) vertebra is equal to 1*5 

 inches; of the largest (say 3 8th), 2*15. 



There appear no dorsals or lumbars in either of these sets of 

 vertebrae ; there may have been thirty of them. 



Nine very distinct caudals appear in the collection from Baldon. 

 Eight of these are consecutive. They occupy a length of 16-9 

 inches; the most forward four occupy 9-0, and the latter four 7*9, 

 the reduction of thickness being regular. The breadth of the 

 anterior face of the longest of the eight is 3-9 inches, of the smallest 

 3' i. The separate vertebra (23rd) has a breadth of 2.0 inches. 



B b 2 



