Cope.l 2QQ [January 20, 



I. The vertebrfe plane, moderately elongate. 



Tail very long, compressed; fore limb small; no diapophyses 

 on lumbar region Elasmosaurus. 



Tail short, depressed; forelimb strong; diapophyses on lumbar ver- 

 tebrae CiMOLIASAURUS. 



II. The vertebrte with very short antero-posterior diameter, slightly 

 biconcave Crymocetus. 



The species indicated are seven, as follows : 



Elasmosaurus Cope. 



Elasmosaurus platyurus Cope. Proc. Acad. Nat. Sci., Phil., 

 18G8, 92. 



Length about forty-five feet; bulk of body near that of an ele- 

 ■ phant. The upper cretaceous of Kansas. 



Elasmosaurus orientalis Cope, MS. 



Dimensions similar to those of the jireceding. The Cretaceous 

 Green-sand of New Jersey. 



Elasmosaurus eonstrictus. Pledomurus constricius Owen, 

 British Reptiles. 



Known only from a caudal vertebra from the British Chalk. 



CiMOLIASAURUS Leidy. 



ChnoUasaurus, Discosaurus and Brimo'^aurus Leidy. 



Cimoliasaurus miagnus Leidy, Cretaceous Reptiles N. Am. 

 Discosaurus vetustus Leidy 1. c. 



Cretaceous Green-sand of the Eastern United States. 



Cimoliasaurus grandis Leidy. Brimosaurus grandis Leidy. 

 Proc. Acad. Nat. Sci., Philad., 1854, 72. 



L^pper cretaeeous of Arkansas. 



Cimoliasaurus latispinus. Plesiosaurus latiqnnus Owen, Brit- 

 ish Reptiles. 



From the Green-sand of England. Perhaj^ it is an Elasmosaurus. 



Crymocetus Cope. 



Crymocetus Barnardi. Plesiosaurus Barnardi Owen, British 

 Reptiles. Pala;ontographical Soc, Cretac. Rept., Tab. xviii. 



From the chalk of England. This species is founded by Owen on 

 supposed cervical vertebras. They appear to me to be rather lumbars, 

 and to indicate an ally of the preceding genera. 



