140 SAUROPTEKYG1A. 



Pliosaurus brachyspondylus, Seeley l . 

 Pliosaurus nitidus, Phillips 2 . 

 Pliosaurus simplex, Phillips 3 . 

 Pliosaurus gamma, Phillips 4 (ex Owen). 



The specimens from the Kimeridge Clay which have been described 

 under the foregoing names are all evidently referable to immature 

 individuals probably belonging for the most part either to P. brachy- 

 dirus or P. ma-crornerus. Their immaturity is shown by the extreme 

 smoothness and the flatness of the terminal faces of the vertebrae, 

 and the relative shortness of the ischia (fig. 44), of which the free 

 borders were evidently covered with cartilage. The base of the 

 neural canal of the vertebrae is also very clearly marked, and its 

 posterior expansion very wide, owing to the incomplete development 

 of the arch. Neither of the above-mentioned names, except those 

 given by Phillips, were sufficiently defined to have a right to 

 supersede the name P. macromerus. 



R. 1243. Cast of the centrum of a late posterior cervical vertebra. 

 The original was obtained, in association with thirty 

 dorsals, from the Kimeridge Clay of Ely, Cambridge- 

 shire, and is preserved in the Woodwardian Museum at 

 Cambridge. It is noticed by Seeley in his ' Index to 

 Aves &c. in Cambridge Museum,' p. 97 (No. e. 5), under 

 the name of P. brachyspondylus ; the associated dorsals 

 being described on pp. 102, 103 of the same. The 

 present specimen is remarkable that while on the right 

 side there is only a single costal facet, on the left there 

 are two such facets. The terminal faces are quite flat ; 

 and the broad posterior expansion of the base of the 

 neural canal is well shown. The dimensions are : — length 

 0,038 (1-5 inches), height 0,071 (2-8 inches), width 0,805 

 (3-2 inches). The specimen closely accords with the type 

 posterior cervical of P. nitidus figured by Phillips in his 

 ' Geology of Oxford/ p. 360, fig. 156. 



Made in the Museum, 1888. 



31925. An entire anterior dorsal vertebra, together with the ribs, 

 of a somewhat smaller individual ; from the Kimeridge 

 Clay of Shotover, Oxfordshire. Accords exactly with the 

 dorsal figured by Phillips, p. 361, fig. 157, as one of the 



1 Index to Aves &c. in Cambridge Museum, p. 102 (1860). 



2 Geology of Oxford, p. 360 (1871). 



3 Ibid. p. 366. 



4 Ibid. p. 358. 



