158 THE MAMMALIA OF THE DEEP RIVER BEDS. 



scaphoid, but the inferior one is very large and passes without interruption into the 

 surface for the magnum, which is altogether lateral in position. In M. ccenopus the 

 magnum facet is strongly convex, but in M. montanus it is almost flat. The lunar 

 rests entirely upon the unciform and its whole distal surface is occupied by the large 

 concave facet for that bone ; it is very oblique in position and forms, with the mag- 

 num surface, a sharp edge or beak which descends almost to the third metacarpal 

 and prevents any anterior contact between the magnum and unciform. 



The cuneiform has an oblique position in the carpus, running outward and back- 

 ward from the lunar. In shape it is rather low and narrow, but greatly extended in 

 the dorso-palmar direction. The radial side presents two facets for the lunar, of 

 which the proximal one is very small and the distal one quite large. The proximal 

 surface for the ulna is a simple groove and the facet for the pisiform is large, triangu- 

 lar and almost flat. The distal face of the. bone is occupied by the large and simply 

 concave surface for the unciform. 



The trapezium is preserved in Prof. Cope's type specimen and, as in the case of 

 Mesoreodon, demonstrates that the pollex was not present. It is a small nodular 

 bone which appears not to touch the scaphoid but to articulate merely with the 

 trapezoid and second metacarpal. 



When seen in position, the trapezoid appears to be as large as the magnum, but 

 is really very much smaller in all its dimensions. The proximal side forms a narrow, 

 imperfectly saddle-shaped facet for the scaphoid, and on the palmar side is a small 

 surface for the attachment of the trapezium ; on the ulnar side the trapezoid is closely 

 applied to the magnum. The metacarpal facets are two in number, a large distal 

 one for the second and a small infero-lateral one for the third metacarpal. 



The exposed anterior face of the magnum is quite small and yet the bone is a 

 rather large one. The proximal surface is altogether taken up by the facet for the 

 scaphoid, the contact with the lunar being entirely lateral. The scaphoid surface is 

 very convex and rises steeply towards the palmar side to form an ill-defined head. 

 The lunar facet is but slightly concave and in this respect is very different from the 

 surface which occurs in M. ccenopus, where the magnum encloses the lunar almost in 

 a semicircle. On the radial side of the magnum is quite a deep concavity which 

 receives the trapezoid. The hook-like process which is given off from the palmar 

 side of the magnum is long and heavy and is strongly recurved towards the radial 

 side. The distal side bears a saddle-shaped facet for the third metacarpal, but there 

 is no anterior contact with the second. 



The unciform is a large bone of irregularly cuboidal shape. The proximal sur- 

 face is almost equally divided between the facets for the cuneiform and lunar, though 



