346 



THE PORTLAND OOLITE PERIOD. 



CHAP. 



Length of these last, 2*0 inches; breadth, 4-3 (including the 

 cicatrices, 5*0); height, 3*75; or, if length = 100, breadth = 210, 

 height = 187. 



Fifteen cervical vertebrae from Shotover, apparently belonging 

 to this species, have the following proportions : Length being 100, 

 breadth varies from 293 to 308, and height from 243 to 188. 



The dorsal vertebrae have the articular faces nearly plane and 

 (except in the anterior bones which are wider) nearly circular, but 

 truncated above by the neural cicatrices and canal. The neural 

 canal is much contracted in the middle, and much widened behind. 

 The neurapophysis is stated by Owen to rise 7 inches, so as to 

 make the dorsal vertebra 1 1 inches high. The zygapophyses appear 



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



i. Dorsal vertebra, seen from below. 2. The same, seen from above. 

 3. The same, seen in front. 



to have articulated by plane oblique surfaces, not in spoon-shaped 

 processes as in plesiosaurus, but none are perfect. The sides and 

 lower surface evenly convex, contracted in the middle, and smooth 

 except at the edges, which are more or less roughly furrowed. 

 Four foramina appear. The whole has a cylindrical aspect. The 

 transverse processes are very prominent, directed upward, and have 

 large convex articulating ends for round-headed ribs. 



Length, 3*85 inches ; breadth, 4-15 ; height to the canal, 3*75. 



