THE CHIMPANZEES AND ORANGS. 21 
hallux (i) and the other digits (i—v), and greater inequality in respect of length, than in 
Man: above all, the innermost digit, by express modification of size and shape of the 
entocuneiform (7), is set at nearly a right angle to the other toes, converting the foot into 
a hand, and one gifted with a prodigious power of grasp (Pl. XI. fig. 2). These pecu- 
liarities involve modifications of greater or less degree in all the tarsal bones. 
The naviculareorscaphoid (n), answering to the carpal bone of the same name, is broader 
than in Man and less deep,—the dorsal surface being more on the same plane, not bent 
down so abruptly as the inner (tibial) side, increasing also more in breadth towards that 
end which is produced, as an obtuse process (n), beyond the contiguous parts of the astra- 
galus (a) and entocuneiform (7). This strong tubercle of the naviculare receives part of 
the insertion of the tibialis posticus muscle, and shows a smooth facet for the bursa 
interposed between it and the major part of the tendon proceeding to the entocuneiform. 
The proximal concavity for the astragalus is broader and deeper transversely than in 
Man, and less extended vertically. The distal articular surface covers a smaller 
proportion of that part of the bone, both transversely and vertically, than in Man. The 
inner facet, for the entocuneiform, is more convex than in Man ; the middle facet is also 
convex, but is flat in Man; the outer facet is more concave than in Man. The feeble 
concavity of the outer, and convexity of the inner, facets in the Human naviculare, 
seldom noticed in Anthropotomy, receive a new significance from this comparison with 
the Gorilla. The proximal and distal articular surfaces of the naviculare are separated 
by a less thickness of bone at the outer (fibular) end in the Gorilla than in Man; never- 
theless the facet for the cuboides, inconstant in Man, is present in the four instances of 
the Gorilla examined by me. The naviculare of the Gorilla is nearly twice the weight 
of that in Man; its ‘tibial’ production, with the corresponding inclination of the 
coarticulated part of the astragalus, more plainly shows its true character, as the 
innermost of the proximal row of tarsal bones, than could be seen in Man. 
The astragalus (Pl. XI. fig. 2, a), answering to the lunare of the wrist, exclusively 
affords the articular surface to the bones of the leg. In the Gorilla it expands more 
as it advances, and becomes broader in front; it slopes more from without inward 
and downward, and the facet for the malleolar process of the tibia is less vertical and 
less defined from the upper surface than in Man (fig. 1, a) ; that surface is less convex 
from behind forward, and is rather more concave transversely than in Man, showing 
a less extent of the raising and depressing movements of the foot, and greater freedom 
and frequency of the movement from side to side, especially of inversion of the 
sole. The fibular facet resembles that in Man; but its lower angle is turned rather 
more outward. The groove for the flexor longus pollicis at the back part of the 
bone is wider than in Man; the posterior concave surface is less deep transversely, 
the tibial border being less produced downward. The groove dividing this from 
the anterior articular surface is deeper in the Gorilla. The anterior surface for 
the calcaneum resembles that of Man; it joins at a similar angle the convexity for 
