374 



THE PORTLAND OOLITE PERIOD. 



CHAP. 



height 94; and the anterior dorsal has length 100, breadth 

 height 96. 



The faces of all these vertebrae are equally, but very slightly, 

 concave ; the sides are deeply impressed ; the base somewhat 

 convex along the middle, with two large rather depressed approxi- 

 mate foramina, the processes attached by long oval cicatrices, which 

 in the smaller vertebrae are nearly central, but farther along the 

 column occupy a posterior position. 



Another series of vertebrae, smaller than those last mentioned, 

 though differing a little in some particulars, must be placed 

 very near to them in a natural series. These are three in number, 

 posterior cervicals just passing into dorsals. 



123 



Diagram CLXX1V. Plesiosaurus allied to P. plicatus. 

 i. Seen on left side. 2. Seen below. 3. Seen above. 



PLESIOSAURUS INFRAPLANUS. n.s. 



There is yet another form of cervical vertebrae from Shotover, 

 Stanford, and Brill, longer, rather more depressed, and with the 

 lower face flattened between the approximated foramina, by which 

 it differs from P. carinatus. The lateral cicatrices are deep, and 

 placed in the middle of the length. A specimen from Stanford is 

 longer in proportion, and rather more depressed. 



Length of a specimen from Brill, 1-79 inches; breadth, 2*03; 

 height, 1*82 : or, in proportions, length, 100; breadth, 113; height, 

 101. 



PLESIOSAURUS CARINATUS. n.s. 



A small species with remarkably neat, well-defined vertebrae, 

 cervical, dorsal, and lumbar, comes from Quainton in Buckingham- 

 shire, probably, but not certainly, out of the Portland rock. The 

 bone is dense and fine-grained. 



