90 



is relatively about as long as in the English Pleswsauri, and the adjacent part 

 of the bone has a similar form. 



Measurements. 



M. 



Length of the anterior cervical 0.062 



Depth of the articular face of the anterior cervical 0. 050 



Width of the articular face of the anterior cervical 0. 050 



Length of the posterior cervical 0.070 



Depth of tho articular face of the posterior cervical 0. 052 



Width of the articular face of the posterior cervical 0.090 



Distance between parapopbysial pits 0. 048 



Length of the anterior dorsal vertebra 0. 059 



Depth of the articular face of the anterior dorsal 0. 062 



Width of the articular face of the anterior dorsal 0. 072 



Width of the neural canal on the centrum 0.017 



Long diameter of the proximal cud of the clavicle 0. 114 



This saurian is readily distinguished from the Elasmosaurus platyurus, 

 Cope, by the relatively shorter cervical vertebrae and. the regular acute ridges 

 on the exterior surfaces near the margin of the articular faces, as well as the 

 less contracted form of all the vertebral centra. As the neural arches and 

 the cervical parapophyses are not coossified with the centra, the species is 

 referred to the genus Plesiosaurus. 



The bones of this reptile and those of a smaller species, probably a 

 Clidastes, were found in close proximity, near Sheridan, Kansas, by Joseph 

 Savage, of Leavenworth. According to this gentleman, the vertebral column 

 of the Clidastes was found immediately below that of the plesiosauroid, and 

 in a reversed position, as though it had been swallowed by the latter, and larger 

 reptile. The largest vertebrae of the Clidastes were about three-quarters the 

 length ami one-fourth the diauietej of those of the plesiosauroid, and the 

 animal must have furnished a large, or at least a long, mouthful for its captor. 

 The bones of the Clidastes were not in good condition, and resembled those 

 of C. cineriarum. Cope, though smaller. 



TESTUDLNATA. 



This order is but sparingly represented in the marine formation of No. 3, 

 and more abundantly in the fresh-water beds of No. 6. Of the former, there 

 arc three species, two of them with natatory limbs of the character now 

 known among sea-turtles. Of the latter, all are Trionychidce and Emydidce; 

 the laud-tortoises not appearing among them, according to present information. 



