xni. PLEIOSA UR US. 345 



Length, r6 inch ; breadth, 3-9 ; height, 3-4 to the neural canal ; 

 or, if length = 100, breadth 244, height = 312. 



123 



Diagram CXXXVII. Pleiosaurus brachydeirus. Scale one-fifth of nature. 



I. Cervical vertebra, seen on the left side. 2. The same, seen in front. 

 3. The same, seen from above. 



A seventh cervical vertebra, which perhaps follows immediately, 

 has the lateral cicatrices not completely double; from this point 

 these scars rise rapidly on the following vertebrae, and on the tenth 

 it is a large oval space, no longer distinctly double. Of these 



Diagram CXXXVIII. Pleiosaurus brachydeirus. Scale one-fifth of nature. 

 I. Posterior cervical, seen on the left side. 2. The same, seen in front. 



vertebrae the central parts of the articular faces are tumid; the 

 greatest diameter is above the centre; the thickness augments. 

 They may perhaps be as well called anterior dorsals. 



c Professor Owen describes an extraordinary cervical vertebra, possibly of this 

 species, in the following words : 



' Perhaps there is no example, save the genus Pleiosaurus, in the whole class of 

 reptiles, living or extinct, which has any of the vertebrae presenting such proportions 

 as those of the following specimen in Dr. Buckland's collection from the Kimmeridge 

 clay of Foxcombe Hill near Oxford. The breadth of the body of this vertebra is six 

 inches ; its depth, or vertical diameter, five inches ; while in length it measures only 

 an inch and a half.' 



These measures give the unexampled proportions of Length, 100 ; breadth, 400 ; 

 height, 333. 



It is to be regretted that this, and some other specimens of importance to the 

 study of fossil reptiles, can no longer be found in Dr. Buckland's collection. 



