188 MR. ST. G. MIVART ON THE SKELETON OF THE PRIMATES. 
does not articulate with the trapezoides and os magnum, being separated from them by 
the os intermedium. 
The proximal or superior side of the scaphoides articulates with the radius by a large 
rounded surface, which is decidedly less convex than the corresponding one of Man, or 
than that of the Gorilla, and is much like that of the Chimpanzee (Pl. XLII. fig. 2 a). 
It is less quadrate than in the Gorilla, and less transversely elongated than in Man. 
The radial tuberosity (Pl. XLII. figs. 2-4, 6) appears much produced, because of the 
narrowness of the bone. It is not, however, really very much more so than in Man, and 
is not so much so as in Troglodytes. There is a deeper concavity between the tuberosity 
and the radial articular surface than in Man. 
The distal, or inferior, side of the bone presents a strong concavity divided by a 
transverse prominence into two articular surfaces. The smaller and more proximal of 
these (Pl. XLII. fig. 3c) joins the semilunare, and, as in Troglodytes, is larger than the 
corresponding surface of Man. The one nearer the palmar (or more distal) surface is 
more concave, and articulates with the ulnar end of the os intermedium. Palmad and 
radiad of this is a small irregular surface, with several vascular foramina; and radiad, 
again, of this last surface is another smaller articular one (Pl. XLII. figs. 3 & 4, e) for 
the radial side of the third or proximal face of the intermedium. External again to 
this (7. e. on its radial side), and on the inferior aspect of the base of the tuberosity, is 
a small surface (Pl. XLII. fig. 4) which joins the trapezium. 
On the upper part of the bone, towards its ulnar side and between the surfaces for 
the radius and semilunare, is a small irregular tract of bone with vascular foramina. 
The interspace on the dorsal surface of the carpus, between the scaphoides and 
intermedium, answers to the dorsal groove of the scaphoid of Man and Troglodytes. 
Intermedium. (Plate XLII. figs. 5, 6.) 
The intermedium is a slightly crescentic bone, but not very dissimilar in shape to the 
cuneiforme, which about equals it in size; its extension, however, is mainly in the 
transverse direction. 
It may be described as having three surfaces and three borders. 
The first of these surfaces (Pl. XLII. fig. 5), and the one which looks backwards, 
downwards, and more or less radiad, consists for the most part of a transversely extended 
and slightly convex articular surface for the trapezoides. The ulnar end, however, pre- 
sents a rough tract for the attachment of ligaments. 
The second surface, which looks palmad, downwards, and ulnad (Pl. XLII. fig. 6), 
is concaye, and articulates with the rounded head of the os magnum. 
The third surface, the one which looks upwards and rather ulnad, is convex, and 
skeleton No. 5083 A, in the Museum of the Royal College of Surgeons, almost demonstrates this homology, as 
in that Chimpanzee the seaphoid has a development almost exactly corresponding to that of the scaphoid, plus 
the intermedium, of the Orang. See Philosophical Transactions, vol. clvii. (1867) plate xiv. fig. 1. 
