Ghelonia. 
41 
Fig. 54. — a, Frontal, and b, Palatal aspects of the cranium of a young individual of 
Argillochelys cuneiceps (Owen), from the London Clay of Sheppey. pmx, premaxilla; 
mx, maxilla; pt, pterygoid; ept, ectopterygoid process of the pterygoid; bo, basi- 
occipital; a, occipital shield; 6, paraoccipital shield; c, interparietal shield; d, 
frontal shield. 
Fig. 55. — The imperfect carapace of Plesiochelys valdensis (Lydekker), Weal den, Isle of 
Wight (’ nat. size), nu } nuchal bone ; nl-nl, neural bones ; cl-c7, costal bones. 
Tektiaey and Secondary Chelonia. 
