PLESIOSAUEID^. 



271 



2056*. An imperfect late cervical vertebra, apparently referable to 

 this species ; probably from Lyme-Regis. 



Hawkins Collection. Purchased, 1834. 



C. Longirostrine Group. 

 Skull comparatively large, with long mandibular symphysis. 

 Cervical vertebras of moderate length, vrith the terminal faces of 



Fig. 81. 



pr.z- 



Plesiosatirtis rostratiis. — Left lateral and posterior aspects of a middle cervical 

 vertebra ; from the Lower Lias of Lyme-Eegis. i. Letters as in fig. 69, p. 225. 



the centra deeply cupped, the costal facets either single or double* 

 and the neural spines very short. Pectoral girdle unknown. 



This group is represented in the Upper Lias by P. longirostris, 

 Blake \ which is probably identical with P. ccelospondylus, Owen \ 

 It is not improbable that Peloneustes may be directly descended from 

 this group. 



Plesiosaurus rostratus, Owen 3 . 



Of comparatively large size, the length exceeding 12 feet. Skull 

 with the prem axillary region produced into a spatulate rostrum. 

 Neck probably of considerable length, the number of vertebrae being 

 unknown. Cervical vertebrae with the cupped terminal faces of 

 the centra bevelled at the edges, and the haemal surface with a 

 prominent ridge flanked on either side by a deep pit; in the 

 anterior region the apparently single costal facet placed low down 



1 In Tate and Blake's ' Yorkshire Lias,' p. 250 (1876). 



2 Liassic Kept ilia (Mon. Pal. fcioc.), iSauroptengia, p. 12 (1865).- 

 ciently characterized. 



s Ibid. p. 20 (1865). 



Insuffi- 



