1^98 
TEliTlAliY VERTEEKATA OF THE FAYOM. 
short pedicle and is considerably below the level of the lower border of the com- 
pletely closed tympanic ring, which is oval in outline. So far as can be determined, 
the form and relations of the squamosal, quadrato-jugal, and jugal do not differ 
in any im[)ortant respect from those of the same elements in Fodocnemis, and the 
same may be said for the bones of the side of the cranium. The large foramen 
i^plienoidale [f-s.) is shown in PL XXV. fig. 1, opening in front of the epiotic. 
The sympliysial region of the mandible (PI. XXV. fig. 3, sym.) is very large and 
massively constructed. In form it is roughly pentagonal, the two anterior sides 
forming the labial borders, the two laterals being produced upwards into strong 
pointed coronoid processes [cor.), while the posterior side is slightly concave. This 
posterior border is greatly thickened and deeply grooved ; in front of it the bone 
thins gradually towards the labial borders. The lateral edges of the symphysis are 
also deeply grooved {m.g.), the groove being continued back on to the rami as far as 
the articulation. The ventral surface of the symphysis is very slightly convex in all 
directions ; it is separated from the ventral surface of the rami by shallow grooves, 
and probably was covered by a single large horny plate. The rami are not only 
deeply grooved on the outer face, as already mentioned, but are also hollowed on the 
inner side. The articular surface [art.) for the quadrate is large ; it is convex from 
side to side and slightly concave from before backwards : behind it there is a blunt 
angular process [ang.), the upper surface of which is concave. 
The extraordinary massiveness of the sym]diysis and the great development of the 
processes and grooves for the attachment of the jaw-muscles indicate that the jaws 
with their horny covering must have formed a very powerful crushing-ap[)aratus. 
A similar modification is observable in some Cyptodiran tortoises, e. g. Lgtoloma, 
described and figured by Dollo *. 
Although in no case have the carapace and plastron been found associated with 
the skull in such a manner as to leave no doubt that they belong to the same 
individual, nevertheless the shell now to be described may be regarded with reasonable 
certainty as belonging to the present species. In the first ])!ace, this form of shell, lik(^ 
the skull, is the commonest occurring in the Qasr-el-Sagha beds, and in the second 
place it differs widely from the shell of Podocnemis, the only other rieurodiran genus 
found at this horizon. 
The most nearly complete specimen is a somewhat crushed shell (text-fig. 9(>), 
both carapace and plastron being so coated with gypsum that many of the sutures 
and most of the grooves between the epidermal plates cannot be seen, 'fhe carapace 
(text-fig. 9G, A) is depressed, this being in part due to crushing, though it is clear 
tliat the shell was much wider and less convex than in the next species, S. liht/ca, 
approaching in this respect X as described by lieinach. The number 
* Hull. Mus. Roy. Hist. Nat. Bolge, vol. iv. (1880) p. 129. Soo also J.ydeklicr, Froc. Zool, Soc. 1889, 
p. GO. 
