282 



SAUROPTERTGIA. 



11903. An ulna indicating an individual of the approximate size 

 of P. dolichodirus ; from Lyme-Regis. Mantell Collection. 



R. 1399. A fibula; from Lyme-Regis. This specimen indicates an 

 individual about the size of P. rostratus. No history. 



Serial Position Uncertain. 



Plesiosaurus costatus, Owen 1 . 



Of large size, but very imperfectly known. Cervical vertebrae 

 with centra of moderate length ; their terminal faces subcircular, 

 deeply cupped, and without bevelling of the edges ; two costal facets, 

 of which the upper is approximated to the n euro-central suture ; 

 haemal surface with a very prominent ridge, on either side of which 

 is a deep ovoid pit ; margins of external surface of centrum rugose. 



This species was founded upon the evidence of an anterior cervical 

 vertebra from the Rhaetic of Aust Cliff, near Bristol, of which the 

 dimensions are : — length 0,038 (1*5 inches), height 0,046 (1-8 

 inches), width 0,05 L (2-0 inches). Avery similar vertebra from the 

 Rhaetic of Autun (Saone-et-Loire), France, is described and figured 

 by Sauvage in the ' Ann. Sci. Ge'ol.' vol. xiv. art. 3, p. 24, pi. vi. 

 fig. 5 (1883). 



Hah. Europe (England and France). 



31882. A somewhat imperfect late cervical vertebra ; probably from 

 the Rhaetic 2 (Upper Trias) of the neighbourhood of Bristol. 

 The neural spine is wanting, but the right side of the 

 arch and centrum is well preserved. The dimensions of 

 the centrum are : — length 0,049 (1*95 inches), height 

 0,059 (2-32 inches), width 0,069 (2-74 inches). This 

 specimen agrees in all its characters with the type, showing 

 the same deeply cupped terminal faces, the approximation 

 of the upper costal facet to the neuro-central suture, the 

 prominent haemal ridge, and the rugosity of the borders 

 of the free surface of the centrum. Purchased, 1859. 



Of the following specimens some may belong to the present and 

 others to the next species. 

 49. The crown and part of the root of a large tooth, in matrix ; 

 from the Rhaetic bone-bed of the " Old Passage," near 

 Bristol. Presented by Sir Henry Delabeche. 



1 Eep. Brit. Assoc, for 1839, p. 80 (1840). 



2 The matrix and mineral condition of this specimen differ from those of 

 Lower Liassic specimens, and Mr. Etheridge has little doubt that it is really 

 Rhretic. 



