PLESIOSAURID^. 211 



than those to which the caudals of No. 46488 of C. eury- 

 merus belonged ; the centrum is also more elongated in a 

 vertical direction. Sharp Collection. 



47169 k. The centrum of an anterior caudal vertebra; from Stilton. 

 This specimen was associated with the preceding, and has 

 the terminal faces crushed in in the same manner. 



Sharp Collection. 



B. Typical Group. 



Vertebrae with the centra usually more or less elongated (especially 

 in the anterior cervical region), and their terminal faces nearly flat ; 

 cervicals with the neural spines tall, the zygosphenes deep, and the 

 zygapophyses much curved ; in some cases anchylosis of the chevrons 

 to the caudal centra. Humerus relatively small, with moderate 

 distal expansion, and with the trochanter in some cases small and 

 never extending obliquely outwards from the shaft ; when only the 

 radius and ulna articulate with the humerus the ulna less elongated 

 transversely than in the preceding group, and separated by an 

 interval from the radius. 



This group includes the type species, and also Elasmosaurus of 

 Cope, Mauisaurus of Hector, and the type of Murcenosaurus of 

 Seeley. 



Cimoliosaurus magnus, Leidy \ 

 Syn. Discosaurus vetustus, Leidy 2 . 



The type species, known only by detached vertebrae. Of largo 

 size, but smaller than C. constrictus. Cope's identification of Disco- 

 saurus vetustus with this species has been already mentioned. The 

 vertebras figured by Leidy as lumbar are really cervical. The 

 species was founded upon the evidence of vertebrae from tho Cre- 

 taceous of New Jersey ; Discosaurus being described on specimens 

 from both that district and Alabama. 



Hob. North America. 



40981 a. An imperfect vertebra probably belonging to the lumbar 

 region ; from the Cretaceous of Withers-Green County, 

 Alabama. From the subcylindrical terminal faces of the 

 centrum it is inferred that this specimen belongs to the 

 lumbar rather than tho " pectoral " region, since tho 



1 Proc. Ac. Nat. Sci. Philad. for 1851, p. 325 (1862). 



2 Ibid. p. 326. 



p2 



