188 ME. ST. G. MIVAKT ON THE SKELETON OF THE PEIMATES. 



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 (PI. XLII. fig. 2 a). 

 It is less quadrate than in the Gorilla, and less transversely elongated than in Man. 



The radial tuberosity (PI. XLII. figs. 2-4, b) appears much produced, because of the 

 narro\vness 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 (PI. XLII. fig. 3 c) 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 smaU irregular surface, with several vascular foramina ; and radiad, 

 again, of this last surface is another smaller articular one (PI. XLII. figs. 3 «& 4, e) for 

 the radial side of the thii'd or proximal face of the intermedium. External again to 

 this [i. e. on its radial side), and on the inferior aspect of the base of the tuberosity, is 

 a small surface (PI. XLII. fig. 4y) 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 ^ ascular 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 (PI. 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 (PI. XLII. fig. 6), 

 is concave, 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. 508.3 A, in the Museum of the Royal CoUege of Surgeons, almost demonstrates this homology, as 

 in that Chimpanzee the scaphoid 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. 



