720 



n. G. SEELET ON THE VERTEBRAL COLUMN 



pressed from side to side below the attachment of the neural arch. 

 The width of the facet for the neurapophysis is 1-| inch. The antero- 

 posterior measurement of the centrum is 2| inches. The lateral or 

 visceral surface of the centrum now becomes more perfectly rounded 



Fig. 5. — View of the Right Side Eig. 6. — Posterior Aspect of the First 

 of the First Dorsal Vertebra, Dorsal Vertebra, \ nat. size. 



\ nat. size. 



a. Sutural surface for the 

 neural arch. 



a. Interspace between the articular face 

 of the centrum and the neural arch. 



from side to side. There are (on the 29th) two rounded vascular 

 foramina on the base, separated by an interspace of an inch to an 

 inch and a half. The neurapophyses approximate nearer together, 

 being 2| inches apart in outside measurement. 



The 34th vertebra has the centrum 2-j---?- inches long, with the 

 anterior articular face 3^ inches deep, and 3 J inches wide ; it is 

 nearly flat. There is a decided forward hang of the upper part of 

 the centrum, as in the dorsal vertebras of Pliosaurs from the Kim- 

 meridge Clay ; and the centrum still has its greatest anteropos- 

 terior measurement below the middle, though the swelling of the 

 bone on the articular faces in that position has disappeared. 



The three remaining dorsal vertebras are badly preserved. 



If this animal be generically identical with the larger Kimmeridge- 

 clay Pliosaurs, it makes known for the first time the number of 

 vertebrae in the neck in that genus, and the modifications of cha- 

 racter which the cervical vertebrae undergo, and also shows the 

 relative size of the neck-vertebrae to those of the back. 



Os Pubis. 



The bone which I regard as a right os pubis of Pliosaurus Evansi is 

 of oblong form, is very thin except in its articular portions, and is 

 preserved upon the original slab of clay on which it was found and 

 forwarded to Cambridge by Mr. Evans. 



The transverse diameter of the bone at the femoral articulation is 

 14{ inches. This posterior outline consists of two portions: — an 



