196 ME. ST. G. MIVAET ON THE SKELETON OP THE PKIMATES. 



upper end of the aimculai* sui-fiice. This upper part of tlie posterior margin is, as also 

 in Troglodytes, much longer than in Man. 



The lower part of the posterior margin (below the auricular surface) is very decidedly 

 concave, but, as in Troglodytes, the concavity is nothing like so strongly marked as in 

 the human ilium (PI. XXXIX. figs. 1 & 2 (/). Indeed it is rather less marked than 

 appears to be generally the case in Troglodytes. 



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 Troglodytes, 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 (PI. XXXIX. tigs. 2, 3, & 4^), 

 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 (PI. XXXIX. tig. 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 (PI. XXXIX. 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 Chimi^anzee ; 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 Troglodytes, thinner from within outwards, and 

 more vertically 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 Tr'oglodytes, is much longer than in Man 

 (PI. XXXIX. 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. Soc. vol. i. p. 363. W. Vrolik calls it " Bpine pubienne ou eminence ilio-pectinee," ' Kecherches 

 d'Anat. Comp. sur le Chimpanse,' p. 10. 



