134 ON A NEW SPECIES OF DICYNODON 
skull, is shaped like an Egyptian doorway, being high, straight-sided, 
and wider below than above. It is rather more chan ,ths of an 
inch in height, ;%;ths of an inch broad at the base, and ;‘gths of an 
inch at che summit, which is 1 inch distant from the upper edge of 
the occipital plate. 
I have spoken of this great quadrate bony mass as the “ occipital 
plate,” because it appears to me to be formed by the combination of 
all the elements of the occipital bone. There are traces of the 
primitive sutures between the basi-occipital and the exoccipitals ; 
but those which should appear between the exoccipitals and supra- 
occipital are not clearly traceable. On the other hand, there is a 
very distinct line of separation, which externally becomes a space 
jth of an inch wide, between the upper margin of the occipital 
plate and the body and lateral processes of the parietal. This latter 
bone has a triangular outline when viewed from behind, measuring 
fully 12 inch from base to apex. The union of its lateral processes 
with the squamosals is distinctly traceable on one side. The parietal 
process, whose end is rather more than 2 inches from the centre of 
the bone, passes in front of, and overlaps the inward process of the 
squamosal. 
A strong inferior process or “hypapophysis” is seen descending 
from the base of the skull on the right side. The quadrate bone is a 
broad, but comparatively thin, bony plate, 1} inch wide superiorly 
and 3 inches long. Its anterior face and its outer edge are convex. 
The posterior face, which is very concave from above downwards 
superiorly, and convex in the same direction below, is divided by a 
vertical ridge into a large outer portion, whose plane is nearly the 
same as that of the occiput, and a smaller inner division, bent for- 
wards almost at a right angle with the foregoing. The lower moiety 
of this inner division of the posterior face of the bone is pretty closely 
applied to the end of the broad process of the exoccipital. The 
upper moiety forms, with the concave surface of the exoccipital 
above this process, the lateral walls of a deep fossa, roofed over, 
above and externally, by the recurved upper part of the quadratum, 
which is separated from the occipital plate by a small intercalary 
bone. This appears to me to correspond with that bone called “une 
espece d’épiphyse, ou plutot d’os interarticulaire pour le tympanique,” 
in the Monitor, by Cuvier (Oss. Foss. ed. 2, vol. x. p. 16). 
The mandible is imperfect posteriorly ; and a considerable part of 
its symphysial end has also disappeared. It measures about 4 inches 
as it is, but probably attained between 5 and 6 inches in length when 
perfect. The depth of the symphysial part of the mandible could 
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