200 SAUKOPTERYGTA. 



The following specimens are from the Neocomian bone-bed of Potton, 

 Bedfordshire, and were doubtless derived from the Kimeridge 

 Clay. 



42089. A very early (? third) cervical vertebra, wanting the greater 

 part of the neural arch and ribs. This specimen is 

 indistinguishable from the Ely example No. 41802 x. 



Purchased, 1870. 



40444 a. The centrum of a middle cervical vertebra. 



Purchased, 1867. 



40444 b. The centrum of a somewhat later cervical vertebra. In 

 general characters this specimen comes nearest to the 

 cervical described as Plesiosaurus validus, No. R. 1286. 



Purchased, 1867. 



40444 C. An early posterior cervical vertebra. Closely resembles the 

 Ely specimen No. 41802. Purchased, 1867. 



Cimoliosaurus brachistospondyius (Tlulke 1 ). 

 Syn. Plesiosaurus brachistospondyius, Hulke 2 . 



As large as the preceding species, but with the centra of the 

 vertebrae much shorter. This species was founded upon the under- 

 mentioned dorsal vertebrae 3 (No. 45869). The cervicals described 

 below differ from those of O. trochanterius in their relatively shorter 

 centra, and the presumption, therefore, is that they should be referred 

 to this species. 



Hob. Europe (England). 



42089. An imperfect anterior cervical vertebra ; from the Neocomian 

 bone-bed of Potton, Bedfordshire ; derived from the 

 Kimeridge Clay. This specimen is relatively much shorter 

 than the anterior cervicals of G. trochanterius, the dimen- 

 sions of the centrum being : — length 0,035 (1*36 inches), 

 height 0,033 (1-3 inches), width 0,045 (1-77 inches). 



Purchased, 1870. 



40444. A somewhat later anterior cervical vertebra, in an imperfect 

 condition ; from Potton. Purchased, 1867. 



46448. A still later imperfect anterior cervical vertebra ; from 

 Potton. Purchased, 1875. 



1 Quart. Journ. Geol. Soc. vol. xxvi. p. 611 (1870). — Plesiosaurus. 



2 Loc. cit. 



3 In the ' Geol. Mag.' dec. 3, vol. v. p. 354, the writer suggested that the 

 shortness of these "vertebra; might be due to pressure, a view which is not 

 supported by subsequent observations. 



