54 CHELONIA. 



39771. The imperfect cranium ; from the Middle Eocene of Brackles- 

 ham, Sussex. This specimen agrees precisely in size and 

 characters with the more imperfect type cranium, from the 

 same beds, figured by Owen in Dixon's ' Geology of Sussex,' 

 pi. xiii. fig. 4, and also in his ' History of British Fossil 

 Eeptilia,' Chelonia, pi. xxv. fig. 4, from the palatal aspect. 

 The present specimen, which has been somewhat crushed 

 and has lost the extremity of the beak, shows both the 

 frontal and oral aspects. On the former the occipital 

 shield is distinctly seen. The palate agrees with that of 

 the next species in its width and flatness, the absence of 

 distinct ridges, the very low, sloping alveolar walls, and 

 the position of the posterior nares. The basioccipital is 

 absent, and the two pterygoids have been separated in the 

 middle line. The latter bones appear to be less emar- 

 ginate laterally than in the next species; and in this 

 respect, as well in the more elongated inferior apertures 

 of the temporal fossse, the species approximates to Thalas- 

 soehelys. Morris Collection. Purchased, 1867. 



33233. The parieto-frontal region of a larger cranium not impro- 

 bably belonging to this species ; from Bracklesham. The 

 boundaries of the epidermal shields are not visible. 



Hastings Collection. Purchased, 1855. 



25599. The right quadrate with part of the palatal region of the 

 (Fig.) pterygoid attached, and the stapes in situ ; from Brackles- 

 ham. Figured by Owen in his ' Reptilia of the London 

 Clay, &c.' vol. i. pt. ii. pi. xxix. figs. 3, 4, without specific 

 name. This specimen agrees essentially with the corre- 

 sponding part of the skull of the existing Thalassochelys, 

 and differs from that of Chelone, as is shown especially by 

 the long channel for the stapes, the prominent process 

 immediately above, and the small vertical height of the 

 articular portion. Dixon Collection. Purchased, 1851 . 



R. 1025. The mandible, imperfect posteriorly : from Bracklesham. 

 From its correspondence in character with the cranium 

 there can be no doubt that this specimen is referable to 

 the present species. The symphysis is much flattened, 

 but has an indistinct ridge inferiorly. The left side wants 

 only the articular and splenial. 



Presented by P. E. Combe, Esq., 1888. 



