MR. ST. G. MIVART ON THE SKELETON OF THE PRIMATES. 207 
anterior articular surface by a groove for the astragalo-calcaneal ligament. This groove, 
though somewhat deeper than in Man (Pl. XLII. fig. 9%), is not nearly so much so as 
in the Gorilla. 
The anterior articular surface for the os calcis (Pl. XLIII. fig. 9h) is much elongated, 
and is concavo-convex, but it is not very distinctly marked off from the rest of the 
articular surface of the head of the astragalus. 
Naviculare. (Plate XLIII. figs. 14-16.) 
This bone in the Orang has a rather more marked proximal concavity than has its 
homologue in the Gorilla, and a much more marked one than that of Man. 
The vertical diameter of the same surface also predominates over the transverse one to 
a greater degree than in the human naviculare. Simia agrees with Homo, and differs from 
Troglodytes,in having the plantar end of the bone less antero-posteriorly expanded; and 
the tuberosity (Pl. XLII. fig. 15 e) is less produced than in Man, and much less so than 
in Troglodytes. , 
The distal articular surface, as a whole, is narrower, in proportion to its vertical 
extent, in the Orang than it is in the Gorilla, and still more so than in Man. It agrees 
with that of Troglodytes, and differs from that of Man in the marked concavity of the 
surface for the ectocuneiforme (Pl. XLIII figs. 14-164), and in the convexity of those 
for the mesocuneiforme and entocuneiforme. Yet the angle formed by the first of these 
with the surface for the mesocuneiforme is smaller than in the Gorilla, and still more 
so than in Man. In the Orang there is generally a larger facet (Pl. XLII. fig. 16 ¢) 
for the cuboid than in Troglodytes. The rough tract on the peroneal surface of the 
bone (between the facet for the cuboid’and the peroneal margins of the proximal 
and distal articular surfaces) is much more extensive in the Orang than in Man or 
Troglodytes (P\. XLII. fig. 16 d). 
Entocuneiforme. (Plate XLIIL. figs. 22-26.) 
. The entocuneiforme of Simia differs much from its homologue in Man or Troglodytes, 
its tibial surface being strongly concave, as also the margin connecting the surfaces for 
the first and second metatarsals. The articular surface for the metatarsal of the hallux 
hasa greater vertical concavity than in any higher species, being sometimes, indeed, truly 
saddle-shaped (PI. XLIIL. fig. 23 & 24a). Sometimes, however (PI. XLIIL. fig 26 a), this 
vertical concavity is absent. This surface looks rather more tibiad than it does forwards’, 
and it cannot be said to be notched on its inner side—as is the case in Man and 7’yro- 
glodytes. ‘The greater part of the anterior aspect of the bone is occupied by a rough 
non-articular tract which extends upwards and widely separates the surfaces for the 
first and second metatarsals? (Pl. XLIII. figs. 23-26 ce). 
 M. Vrolik remarks that it is so placed “ que le gros orteil doit s’écarter des autres.” ‘ Recherches d’ Anat. 
Comp.’ p. 15. * Noticed by Professor Huxley, see ‘ Medical Times,’ 1864, vol. i. p. 565. 
