48 CHELONIA. 



R. 910. A larger shell, apparently belonging to this form ; from 

 Sheppey. The marginals are wanting, and the carapace 

 has been flattened by pressure, and is otherwise imperfect. 

 The neurals are not distinctly keeled, but the general 

 contour of these bones, as well as that of the vertebral 

 shields, accords with the preceding specimen. The long 

 xiphiplastrals are shown. No history. 



39765. An imperfect shell • probably referable to this species, in 

 which the sides of the carapace have been crushed together 

 by pressure ; from Sheppey. The contour of the bones 

 and shields of the carapace seems to be nearly similar to 

 the last specimen. Bowerbank Collection. 



37208. The imperfect shell of a very young individual, probably 

 referable to this species ; from Sheppey. In the plastron 

 the characteristic form of the ento- and xiphiplastrals is 

 well displayed. Bell Collection. Purchased, 1863. 



38956. An imperfect young shell of a similar type ; from Sheppey. 



Bowerbank Collection. 



Argillochelys convexa (Owen '). 



Syn. Chelone convexa, Owen 2 . 



Puppigerus convexus, Cope 3 . 

 ? Chelone declivis, Owen 4 . 



Distinguished from the preceding species by the more vaulted 

 carapace, in which the middle and hinder neurals are relatively 

 shorter and wider, and generally without a distinct keel, while the 

 vertebral shields are often wider. In the plastron the ossification 

 is still more imperfect. 



As suggested by Owen, it is probable that the characters on 

 which Chelone dedivis was separated are merely due to difference of 

 age. The skulls referred by Owen to the present species are noticed 

 under the heads of A. cuneiceps and Lytoloma planimentum. 



Hah. Europe (England). 



39764. An imperfect shell, provisionally referred to this form ; 

 from the London Clay (Lower Eocene) of the Isle of 

 Sheppey. This specimen, in which three of the middle 



1 Rep. Brit. Assoc, for 1841, p. 178 (1842).— Chelone. - Loc. cit. 



3 Trans. Amer. Phil. Soc. vol. xiv. pt. i. p. 235 (1870). 



4 Reptilia of the London Clay, &c. vol. i. pt. i. p. 30 (1849). 



