AESINOITHEEIUM. 4o 



because its surfaces agree exactly with those of the radius and ulna of that animal and 

 also with those of the scaphoid just described. The proximal surface of the bone 

 is divided into two articular facets by an antero-posterior ridge. The smaller 

 (postaxial) surface (m.) is for the ulna : it is very slightly convex in front and gently 

 concave behind : its outline is roughly semicircular, the diameter of the circle being 

 represented by the straight postaxial border, beneath which there is a very narrow 

 facet for union with the upper edge of the cuneiform. The rest of the proximal 

 surface (r.) articulates with that part of the radial head that is not received by the 

 scaphoid ; it is roughly triangular and is concave posteriorly and internally, but convex 

 in front. The inner (preaxial) face of the bone bears two surfaces (sc, scJ) for union 

 with the scaphoid : one of these (sc.) along the upper border is long and narrow, while 

 the other (scJ) on the lower side is shorter and broader, and the two are separated by 

 a deep groove. There is also a similar groove on the outer face, separating the 

 upper and lower facets for the cuneiform. The distal surface (mfa;^.), which is triangular 

 in form, is gently convex from before backwards and articulates almost entirely with 

 the magnum, but there is some evidence that near its antero-external angle it slightly 

 overlapped the trapezoid (tr. 1). 



This bone diifers from the lunar of JElephas to a considerable extent, mainly on 

 account of the larger portion of its upper surface that articulates with the ulna. In 

 JElephas the ulnar facet is quite small and is confined to the anterior half of the 

 bone, looking much more outwards than upwards, so that very little of the weight 

 transmitted to the foot through the ulna is borne by the lunar. 



The cuneiform (text-fig. 22) is, on the whole, much like that of Elephas, but its 

 articulation with the ulna {ul.) is larger, extending farther outwards, and this surface 

 is gently convex internally, but concave externally, with a raised outer angle. The 

 surface for the pisiform (p^.) is nearer the inner (preaxial) side of the posterior face 

 of the bone than in Elephas, It is nearly quadrate in outline, and its upper edge 

 joins the posterior border of the ulnar surface : in Elephas this surface is triangular. 

 Postero-externally the lower edge of the bone is produced downwards and 

 backwards into a strong hook-like process. The distal articular surface is very 

 gently convex from before backwards and concave from side to side ; externally it 

 extends outwards for a considerable distance on the ventral face of the process just 

 described. A narrow strip of this surface occupying its inner (preaxial) side is 

 marked ofi" from the rest by a very slight groove : this seems to have overlapped and 

 articulated with the magnum, as mentioned above in the general remarks on the 

 carpus. The remainder of the surface articulated with the unciform. On the inner 

 (lunar) side of the bone there are two facets for union with the lunar {I.) — a 

 broader one along the upper edge and a narrower one along the lower, which projects 

 considerably beyond the upper, from which it is separated by a groove^ 



The pisiform (text-fig. 22, pi.) is tongue-shaped. Its free end is rounded and 



q2 



