2&7 



Tlie sides of" ilie IxkIv are coinparativcly fcel)ly coiistriclcd, much leys lliau 

 in Plesiosaurus, and beneath, the constriction is triHing in degree. 



Transverse processes or diapophyses project from the sides of tlie l)ody, 

 just above its middle and below tlic conjunction of the neural arch. Their 

 bases ate broadly conical; wider than high, and appear originally to have had 

 a sutural connection. The ends are broken off in the specimen. 



The nsual nutritive foramina are visible at the floor of the verteljral canal 

 and beneath the body. 



The peculiarities of the fossil appear to justify its reference to a previously 

 undescribed genus and species, and we have therefore attributed it to an 

 animal with the name at the head of this chapter. 



The measurements of the specimen are as follows: 



Lines. 



Lengtli of body beneatb 12 



Depth of body in front 19 



Width of body iu front 23 



Widtli of body at chevron-facets . 18 



Width of vertebral canal 6 



Leugtb of axis of tlie body 8 



NOTHOSxiURUS. 



NOTHOSAURUS OCCIDUUS. 



The above name was appropriated to a saurian indicated by a detached 

 vertebral body or centrum, represented in Figs. 11 to 13, Plate XV. The 

 specimen was obtained by Professor Hayden on the Moreau River, a tribu-. 

 tary of the Upper Missouri, and is probably a Cretaceous fossil. In form and 

 construction it resembles the vertebral centra of Nothosaurus, an extinct 

 reptile of the Triassic formation of Europe, and probably it belongs to an 

 animal of the same order if not the same genus. The specimen appears to 

 pertain to a dorsal vertebra, to which the neural arcli was attached by broad 

 suture, as usual in the sauropterygians. 



The body is nearly cylindric, longer than wide or liigh, and is moderately 

 narrowed a short distance from the ends. Inferiorly it jirescnts a central 

 roughness, probably for ligamentous attachment. The articular ends are 

 nearly round, but flattened above, and are neai'ly as wide as high. They are 

 slightly concave and exhibit a slight central protuberance, apparently the 

 ossified notochord. 



The sutures for the neural arch extend nearly three-fourths the length 



