44 CHELONIA. 



Argillochelys, sp. b. 



Known only by the mandible, which indicates a form closely 

 allied to, if not identical with, the next species. The mandibular 

 symphysis is wider and flatter than in species a, and the rami are 

 more divergent. 



Hab. Europe (England). 



38099. The nearly entire mandible ; from the Middle Eocene of 

 {Fig.) Bracklesham, Sussex. Eigured by Owen in his ' Eeptilia 

 of the London Clay, &c.' vol. i. pt. i. pi. x. d. figs. 1, 2. 

 The specimen is there stated to be from Hordwell, but its 

 mineral condition and its similarity to the next specimen 

 indicate this to be incorrect. The right articular is 

 wanting. Hastings Collection. Purchased, 1855. 



26134 x. A similar mandible, wanting the greater part of the right 

 ramus ; from Bracklesham. If applied to the type skull 

 of A. cuneiceps, this specimen fits so well that it might 

 almost have belonged to the same individual. 



Dixon Collection. Purchased, 1851. 



38964. A neural bone provisionally referred to this form ; from 

 Bracklesham. In its extreme elongation this specimen 

 agrees with Chelone and differs from Lytoloma, whence it 

 is probably referable to the present genus. 



Hastings Collection. 



Argillochelys cuneiceps (Owen l ). 



Syn. Chelone cuneiceps, Owen 2 . 



Chelone convexa, Owen 3 (in parte). 



The type species. Skull of adult very wide and much depressed, 

 with a sharp descent of the facial profile in the orbital region ; 

 occipital shield thrust back to the posterior extremity of the par- 

 occipitals, which thus meet in the middle line ; interparietal shield 

 elongated, with a deep re-entering angle posteriorly. Mandible 

 unknown, but evidently of the same type as in the preceding form. 



The remarks made under the head of A. antiqua as to the 

 specimens which may probably be the shells of that species will apply 

 equally in the present instance. 



Hob. Europe (England). 



1 Eeptilia of the London Clay, &c. (Mon. Pal. Soc.), vol. i. pt. i. p. 33 

 (1849).— Chelone. - Loo.cit. 



3 History of British Fossil Eeptilia, Chelonia, pi. xxv. figs. 1-3. 



