Ohelonia. 



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; b, paraoccipital shield; c, interparietal shield; d, 

 frontal shield. nat. size. ^SL 



FIG. 55._The imperfect carapace of Plesiochelys valdensis (Lydekker) ; Wealden, Isle of 

 Wight (* nat. size), nu, nuchal bone ; nl-nl, neural bones - r cl-cl, costal bones. 



TEETIABT AND SECONDABY OHKLONIA. 



