Argillochelys cuniceps
A. cuniceps like P camperi is a relatively common turtle and fragments can be found in the pyrite accumulations on the beach, but to find a whole skull or carapace is again, extremely rare.
Three views of a skull, note the palette definition. Similar to P. crassicostatus but more deeply ridged.

Argillochelys sp most probably cuniceps found on the extreme low tide mark on the foreshore October 2012. This is an exceptionally well preserved immature specimen. looking carefully amongst the bones at the top of the left hand image the partial remains of the skull can be seen.

A recent find by David Wells of Sheerness who found this specimen eroding from a clay slip on the beach betwen Paddies Point & Eastchurch gap. This specimen has an almost complete set of nural plates, esential for identification.
Upper and lower view of an almost complete carapace
 
Upper and lower view of a carapace, this time more wear is evident, especially to the upper side of the carapace