88 



body than is characteristic of true serpents, and with two pairs of limbs, or 

 paddles. It progressed by the strokes of its paddles, assisted by its powerful 

 and oarlike tail. The body was steadied by the elevated keel of the median 

 dorsal line, formed by the broad, high, neural spines. The snakelike neck 

 was raised high in the air, or depressed at the will of the animal, now arched 

 swanlike, preparatory to a plunge after a fish, now stretched in repose on the 

 water or deflexed in exploring the depths below. 



Comparisons. — In Cimoliasaurus ?nag?ius, the dorsals with elevated diapo- 

 physes have considerably larger centra than those in which they are situated 

 lower down. In E. platywus, these vertebrae are of relatively equal length. 

 The cervical pleurapophyses in C. magnus are anteriorly considerably stouter 

 and less flattened. 



In comparing this species with the Cimoliasaurus grandis, Leidy, from 

 Arkansas, we observe, first, the generic chai - acter of the strong inferior dia- 

 pophyses in the latter. That species marks itself also as a pre-eminently 

 short-necked form, as these anterior dorsals are even shorter than in C. mag- 

 nus, being nearly twice as wide as long. The depth of the articular faces is 

 also relatively greater than in the E. platywus. 



Localities. — This species has been found in various parts of Kansas, be- 

 sides that from which the specimen above described was procured. Prof. 13. F. 

 Mudge obtained vertebrae from a point thirty miles east of Fort Wallace which 

 probably belong to this animal. 



PLESIOSAURUS, Conybeare. 



Two American species have been provisionally referred to this genus : 

 the P. loclacoodii, Cope, from Xo. 3 of New Jersey: and the P. gitlo, Cope, 

 from Kansas. This determination is only temporary, since the structure 

 of the sternum, in which the type-characters of the sauropterygian families 

 are to be observed, are unknown. The two species agree witli Plesiosamus, 

 and differ from Elasmosaurus and Cimoliasaurus in the non-coossification 

 of the arches and centra of the vertebrae. 



Plesiosaurus gulo, Cope. 



The typical specimen consists of eleven cervical, thirteen dorsal, and 

 seven or eight other vertebra?, with portions of scapular and pelvic arch and 

 ribs. 



