298 
TERTIAliY VERTERRATA OF THE FAYCM. 
short ])CMlicle and is considerably bcdow the level of the lower border of the com- 
j)letely closc'd tyin])anic ring, which is oval in outline. So far as can be determined, 
the form and relations of the squamosal, quadrato-jugal, and jiigal do not differ 
in any inq)ortant r('S[)ect 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 
,sj)I/enoidale (f-s.) is showir in PL XXV. fig. 1, opening in front of the epiotic. 
The symphysial region of the mandible (PI. XXV. fig. 3, si/m.) 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 rrpwards into strong 
pointed coronoid p)rocesses (cor.), while the posterior side is slightly concave. This 
])osterior 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 
dee})ly 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 (aug.), the ui)per surflrce of which is concave. 
The extraordinary massiveness of the symphysis 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 place, this form of shell, like 
the skull, is the commonest occurring in the Qasr-el-Sagha beds, and in the second 
])lace it differs widely from the shell of Podocnemis, the only other Pleurodiran genus 
found at this horizon. 
The most nearly complete s})ecimen is a somewhat crushed shell (text-fig. 9(i), 
both carapace and plastron being so coated with gy])sum that many of the sutures 
and most of the grooves between the epidermal plates cannot be seen. The carapace 
(text-fig. 9G, A) is depressed, this being in ])art due to crushing, though it is clear 
that the shell was much wider and less convex than in the next species, !S. lilnjca, 
approaching in this respect X as described by Keinach. Ihe number 
* Bull. Mus. Boy. Hist. Nut. Bulge, vol. iv. (1880) p. 120. See also Eydekker, Proc. Zook Sue. 1880, 
p. GO. 
