CHELONID^}. 



45 



41636. The imperfect cranium ; from the London Clay (Lower 

 (Fig.) Eocene) of the Isle of Sheppey. The type specimen ; 

 figured by Owen in his ' Keptilia of the London Clay, &c/ 

 vol. i. pt. i. pi. xv. The extremity of the beak and the supra- 

 occipital region are wanting ; and the right quadrate and 

 inferior temporal arcade are likewise broken away. The 

 contour of the epidermal shields is very clearly displayed. 

 The two paroccipital shields are in contact, so that the 

 azygous paroccipital, if present, must evidently have been 

 thrust back to the extremity of the supraoccipital, as is 

 often found to be the case with Thalassochelys. The 

 ectopterygoid processes are beautifully shown. 



Toulmin-Smith Collection. Purchased, 1869. 



Fig. 11. 



Argillochelys cuneiceps. — Frontal and palatal aspects of the cranium of an 

 immature individual ; from the London Clay of Sheppey. T . The palate 

 is partially restored from No. 41636. pmx, premaxilla ; mx, maxilla ; 

 pt, pterygoid ; ept, ectopterygoid process of pterygoid ; bo, basioccipital ; 

 a, occipital shield ; b, paroccipital shield ; c, interparietal shield ; d, frontal 

 shield. The bones on the frontal aspect correspond with those of fig. 10. 



44092. An imperfect cranium ; from Sheppey. This specimen, 

 although more imperfect, agrees closely with the preceding, 

 such remnants of the boundaries of the epidermal shields 

 as remain showing the same general contour. 



Purchased, 1863. 



37213 a. The cranium of a young individual, somewhat imperfect 

 {Fig.) posteriorly ; from Sheppey. Figured in woodcut (fig. 11). 



