44 
TERTIAEY VEliTEBliATA OF THE FAYDM. 
it bears on its u])])cr surface a ])rominent knob. The proximal end, which is a 
little wider than the distal, is entirely occupied by an oblong facet for articulation 
with the cuneiform ; connected with the upper edge of this surface there is another 
very narrow facet extending across the whole width of the bone and marking its 
point of contact with the ulna. Connected with the ventral border of the cuneiform 
facet there is a rather irregular rounded surface, somewhat roughened and apparently 
resulting from the occasional contact with the upper face of the posterior process of 
the cuneiform. 
Text-fig. 22. 
Left cuneiform and pisiform of Arsinoltherium zitleU : A, from above ; B, lunar face. 
h, facets for lunar; |u'., pisiform ; mZ., surface for ulna, h nat. size. 
The trapezium and trapezoid are not certainly known. 
The magnum (text-fig. 23) is (piadrate in section anteriorly, but posteriorly it 
narrows considerably at least on its ventral side. The Tip])er surface is gently 
concave in front, but posteriorly is raised into a considerable convexity, the ]>ostero- 
internal slope of which supplied a surface for union with the sca{)hoid (sc.). Most 
