130 Annals of the Transvaal Museum. 
end of the bone is thicker and narrower and bends strongly upwards to 
unite with the corresponding parietal. 
Only a small portion of the brain case could be laid bare. All that is 
known about the hinder end of the brain case is mentioned in the dis- 
cussion of the exoccipitals. In skull No. 1 a portion of the front end of 
the brain case is exposed to view. The wall of the brain c'ase in this part 
is very thick and the inner surface seems to be rough. It is sometimes 
difficult to make out whether a certain portion is matrix or bone. The 
top of the brain case is covered by a very thin plate of bone extending 
from a little distance in front of the parietal foramen to the extreme front 
end of the brain case. This is situated in front of a line connecting the 
middle of the orbits. In the front end of this thin plate there is a deep 
notch. The plate seems to be a portion of the bone forming the walls of 
the brain case. Its upper surface is smooth and it was apparently separated 
from the portion of the parietal in the skull roof immediately above it by 
a very thin layer of matrix." 5 
The lower jaw is represented by three fragments, which, fitted to- 
gether, form about two-thirds of the right ramus (PI. XIX, fig. 1). 
The dentary is a long slender bone. At the front end, where the 
ramus is broken off, the angular still surpasses it in height. Towards the 
back its height diminishes. Its hinder end is broken away, but from 
impressions of the bones on the matrix in this region may be gathered 
that the dentary was in touch with the surangular. It could not be made 
out whether any overlapping took place. The outside of the dentary 
forms a high ridge along the outer side of the teeth. The outer surface of 
the dentary is covered with coarse, longitudinal striae behind ; more 
forward these striae become shorter and thicker. 
The angular forms the greater portion of the outer surface of the 
ramus. The bone is highest in the vicinity of its thickend ossification 
centrum, which lies near its hinder end. The outer surface of the hinder 
part of the bone is covered with thick ridges, which radiate from the 
ossification centrum. The outer surface of the front part is unknown. 
From the front backwards the angular becomes gradually higher, until it 
meets the surangular. From this point it quickly subsides to end perhaps 
in the vicinity of the articular. How far it really goes cannot be ascer- 
tained, because the hinder part of the ramus is still intact and as usual the 
rough bones do not show sutures. The angular only shows a small surface 
at the ossification centrum on the inside of the ramus. This surface lies 
at the hinder end of an infra-Meckelian vacuity. In front of this vacuity 
another small surface of the angular is visible. 
The surangular forms the hinder half of the upper border of the supra- 
Meckelian vacuity. The bone is relatively thin and bent in an S shape, 
its upper part being convex inwards and its lower part convex outwards. 
The upper part of its outer surface is smooth ; this portion was apparently 
covered, in a closed mouth, by the quadrato-jugual. The lower part of 
the outer surface is covered by deep pits and ridges. The sutures with 
the angular and the articular could not be made out. 
* The bone which surrounds the front end of the brain case could only be identified 
with the “ rhinencephalic chamber ” of American Stegucephali. In our specimen it was im- 
possible to find its limits. In a recent comparative study (“ On the Skull of a Pariasaurian 
Reptile, and, on the Relationship of that Type,” P.Z.S. 1914, Ft. 1, p. 155) Watson, 
however, succeeded in identifying this bone with the sphenethmoid of the frog. This valu- 
able work only reached us a few weeks ago, after the MS. of this paper had been sent to the 
printer, and therefore no full use could be made of it/ 
