GEOLOGICAL SURVEY OF THE TERRITORIES. 393 



The allied genus Cimoliasarus, Leidy, possesses a femur, as described 

 iu the work quoted above; it is of shorter aud thicker form than in 

 most Plcsiosauri. 



The skeleton so nearly complete would indicate no violent disturb- 

 ance of the carcass ; but if there were, it would be an unusual accident 

 that all of the four limbs should have been removed from their sockets 

 without leaving even fragments. 



This genus is well distinguished from Plesiosaurus by the peculiarity 

 of the scapular arch. The mesosternum appears to be coossitied with 

 the claviculi, and the three elements form a broad breast-plate. If the 

 claviculus was ever united with the scapula as in Plesiosaurus, no evi- 

 dence of it can be seen in the specimen. Both the clavicular and me- 

 sosternal elements are broader and more extended anteriorly. 



The American genera of Elasmosauridcs may be compared as follows : 



Posterior cervical vertebras without diapophyses: cervicals longer, 

 compressed, neck very elongate. 



Elasmosaurus. 



Posterior cervical vertebras with diapophyses: cervicals quadrate, 

 shorter, depressed, rapidly diminishing in size, hence the neck shorter. 



ClMOLI AS AURUS. 



Professor Owen figures and describes (reptiles of the Cretaceous, Pal- 

 eon togr. Soc.) a vertebra which very closely resembles the cervical of 

 Elasmosaurus. He considers it to be the cervical of a peculiar Plesio- 

 saurus, which he calls P. co?istrictus, remarking at the same time, its 

 remarkably inferior pleurapophyses. This I believe to be a species of 

 Elasmosaurus or an ally, and to be called for the present Elasmosaurus 

 constrictus. 



ELASMOSAURUS PLATYURUS, (COPE.) 



Leconte's Notes, loc. cit. Proceed. Acad. Nat. Sci., 1838, 1. c. 92. 

 Discosaurus carinatus, Cope. Leconte's Notes, 1. c. 



This, after Mosasaurus, the most elongate of the sea saurians yet dis- 

 covered, is represented by a more than usually complete skeleton in the 

 Museum of the Academy of Natural Sciences in this city. It was found 

 by Dr. Theophilus H. Turner, the physician of the garrison at Fort Wal- 

 lace, a point situated three hundred miles westward from Leavenworth 

 on the Missouri River, and some distance north from the Smoky Hill 

 Fork of the Platte River. Portions of two vertebras, presented by him 

 to Dr. Leconte when on his. geological tour in the interest of the United 

 States Pacific Railroad Company, were brought by the latter gentleman 

 to the academy, and indicated to the writer the existence of an unknown 

 Plesiosauroid reptile- Subsequent correspondence with Dr. Turner 

 resulted in his employing a number of men, who engaged in excava- 

 tions, and succeeded in obtaining a large part of the monster. Its ver- 

 tebras were found to be almost continuous, except a vacancy of some 

 four feet in the anterior dorsal region. They formed a curved line, a 

 considerable part of whose convexity was visible on the side of a bluff 

 of clay shale rock, with seams and crystals of gypsum. The bones were 

 all coated with a thin layer of gypsum, and in some places their dense 

 layer had been destroyed by conversion into sulphate of lime. 



The scapular arch was found in large part adhering to the bodies and 

 neural spines of a series of the anterior dorsal vertebras, and was de- 

 tached from it at the academy. The pelvic arch had been slightly 

 crushed, and the lumbosacral vertebras forced into contact with the ischia, 

 where they remain. A broken extremity of the supposed ilium was 



