196 MR. ST. G. MIVART ON THE SKELETON OF THE PRIMATES. 
upper end of the auricular surface. This upper part of the posterior margin is, as also 
in Zroglodytes, much longer than in Man. 
The lower part of the posterior margin (below the auricular surface) is very decidedly 
concave, but, as in Zroglodytes, the concavity is nothing like so strongly marked as in 
the human ilium (Pl. XXXIX. figs. 1&2 9). Indeed it is rather less marked than 
appears to be generally the case in 7'roglodytes. 
The ilium forms a considerable portion of the acetabulum, but not quite so much of 
it as does the ischium. It is altogether superior to the depressed surface (for fat and 
vessels), which surface is entirely formed by the last-named bone. 
The pubis has a horizontal ramus with three surfaces and three prominent lines, as 
in Man. 
The superior or horizontal surface is broader than in 7'roglodytes, though it is never- 
theless considerably narrower than in Man. ‘This surface presents a narrow groove 
running from without inwards, and concave from behind forwards, the concavity being 
much increased by a very large process. This process (Pl. XX XIX. figs. 2,3, & 4p), 
which exists in almost all adults, is entirely formed by the pubis, and, being situated 
at the internal termination of the ilio-pectineal line, is probably (as Professor Owen! 
names it) the spine of the pubis. It is nevertheless so remote from the symphysis 
and so near the acetabulum that it has rather the appearance of an iliopectineal 
eminence. 
The internal surface of the horizontal ramus (Pl. XX XIX. fig. 3) is smooth, and 
(not counting the just-mentioned spine) is narrower vertically, above the obturator 
foramen, than in Man. 
The external or inferior surface is, as in Man, deeply grooved (Pl. XX XIX. fig. 4). 
Indeed it is often much more so than is sometimes the case in him, the Orang in 
this differing markedly from the Gorilla and Chimpanzee; in both of which (as far as 
I have observed) the groove is never more than slightly marked, while in the Chim- 
panzee it is often altogether absent. 
The external extremity of the bone forms but a very small portion indeed of the 
acetabulum. 
The body of the pubis is, as also in 7'rog/lodytes, thinner from within outwards, and 
more yertically extended than in Man; the margin bounding the obturator foramen is 
also thinner than in him. 
There is no spine of the pubis other than the one already mentioned, and no process 
whatever near the symphysis, which, as also in 7roglodytes, is much longer than in Man 
(Pl. XX XIX. -fig.-2's). 
The descending ramus of the pubis resembles that of the Gorilla and Chimpanzee in 
being much wider than that of Man. 
' Trans, Zool. Soe. vol. i. p. 363. ° W. Vrolik calls it ‘‘ Epine pubienne ou éminence ilio-pectinée,” ‘ Recherches 
d’Anat. Comp. sur le Chimpansé,’ p. 10. 
hy eae 
