204 cheloiha. 



R. 248. Cast of an imperfect skull. The original was obtained 

 from the Lithographic Limestone of the Continent, and is 

 figured by Kiitimew, op. cit. pi. xiv. figs. 1, 2, where it 

 is provisionally referred to Plesiochelys. The chief ground 

 for this reference appears to be the depressed contour of 

 the cranium. The palatines are separated in the middle 

 line by the vomer ; the pterygoids are of moderate width 

 and deeply emarginate. There appear to be no distinct 

 nasals, and the temporal fossae were more or less roofed. 

 Egerton Collection. Purchased, 1882. 



R. 463. Cast of a cranium. The original was obtained from the 

 Middle Purbeck of Durdlestone Bay, Swanage, Dorset- 

 shire. This specimen is probably flattened by pressure. 

 It presents some approximation to the preceding ; but the 

 orbits are nearer to the nares. The roof of the temporal 

 fossa is very short. 



Presented by Sir B. Owen, K.C.B., 1884. 



21974 x. Slab exhibiting the oral aspect of an imperfect mandible; 

 from the Purbeck of Swanage, Dorsetshire. The articular 

 region is wanting. Purchased, 1848. 



R. 1523. An imperfect mandible, in matrix ; from the Purbeck of 



Swanage. Xo history. 



44815. Fragment of rock showing the ventral aspect of a nearly 

 similar mandible ; from the Purbeck of Swanage. The 

 articular surface would appear to be of the Cryptodiran 

 type. Presented by B. Bright, Esq., 1873. 



Section IV. AMPHICHELYDIA. 



This name has been proposed 1 to include a number of genera- 

 lized later Mesozoic forms which may be regarded as allied to the 

 earlier (and at present unknown) progenitors of the Pleurodira and 

 Cryptodira. 



They are characterized by having a shell constructed on the plan 

 of that of the Cryptodira and Pleurodira, in which mesoplasfcral 



1 Lydekker, Quart. Journ. Geol. Soc. vol. xlv. p. 518 (1889). 





