212 
Annals oe the Tkansvaal Museum. 
not in connection witli this part. A vertical section over the upper 
and lower connections of the two parts of the angular will make their 
position clear (fig. 13). 
The outer part of the angular continues backwards past the 
connecting portions, but does not reach the protruding border of the 
articulation surface (see also fig. 10). Its hinder border is smooth and 
convex backwards (fig. 4). The surface of this part of the bone is 
slightly convex outwards, but that part of the surface formed by the 
lower process is strongly concave behind, becoming less so towards its 
fore end. 
The inner part of the angular is a thin vertical plate which covers 
the outside of the surangular. It is continued downwards to the 
lower border of that part of the jaw, also behind the outer portion of 
the angular, but the two parts are here divided by an opening. The 
lower border is connected by suture with the parallel prearticular; the 
hinder border in the same, way with the surangular (figs. 5, 8, 10). 
The Surangular . —Only two small parts of this bone are visible 
from the outside, one in the upper hind corner of the vacuity in the 
jaw and the other along* the upper and hinder border of the inner part 
of the angular (fig. 1). An inside view shows the greater part of the 
bone between the articular and the complementary, forming the whole 
upper border of the inner end of the vacuity in the jaw (fig. 2). The 
prearticular and the complementary meet further forwards, and the 
surangular disappears behind these bones in the Meckelian cavity, 
wherein it may be followed far forwards (figs. 9, 15). 
The bone has the shape of a wedge directly behind the dentary 
(figs. 8, 10). The border of this wedge forms the upper border of the 
jaw, and, starting directly behind the dentary, projects at right angles 
over the upper and hinder border of the inner portion of the angular. 
This projecting part of the surangular is broadest under the articula- 
tion surface. This wedge-shaped part is situated between the articular 
on the inside and the angular on the outside, behind the end of the 
inner opening of the vacuity in the jaw. It wedges so far in between 
these bones as to nearly reach their suture bn the lower border of the 
jaw. This height diminishes further backwards. 
The suture with the articular runs from the upper, hinder corner 
of the inner opening of the vacuity in the jaw upwards and backwards 
until it reaches the edge between the inner and upper surfaces of the 
ramus (fig. 6). The upper surface here, in front of the articulation 
surface, is concave, and the suture passes through this concavity and 
backwards to its outer edge. The outer border of the ramus is much 
thicker from this point backwards than forwards, the latter part con- 
sisting of a single sharp edge formed by the surangular and the former 
of two sharp edges separated by a parallel groove. These two are 
situated the one above the other, and are formed respectively by the 
articular and the surangular (fig. 5). The suture between surangular 
and articular runs through the groove, though not through its deepest 
part, but more on the side of the lower ridge. The surangular is here 
only a thin plate which lies against the lower surface of the articular 
(figs. 11 and 12). There was no suture to mark the end of the sur- 
angular here. 
The Articular and the Prearticular . — The hinder border of the 
inner opening of the vacuity in the jaw is formed by the articular. 
