ARSINOITIIETITUM. 
45 
of the rest of this surface articulated with the lunar (/%.), though, as above mentioned, 
a narrow strip on the outer side was probably overlap])ed by the cuneiform ; in no 
specimen of the magnum, however, have actual traces of this overlap been observed. 
The surfaces for the trapezoid on the one liand, and for the unciform [unc.) on the 
other, are similar : each consists of a facet which extends the whole depth of the bone 
in front, but is confined to the upper half posteriorly, the ventral portion of the 
posterior part of the bone being pinched up into a rounded and backwardly 
Text-fig. 23. 
B., 2. C. 
Left magnum of Arsinoitherium zitteli : A, unciform face ; B, from above ; C, from below, 
lu., facet for lunar ; me. 2, me. 3, facets for the second and third metacarpals ; sc., facet for scaphoid ; 
unc., facet for unciform. ^ nat. size. 
projecting knob. The distal surface {inc. 2 and me. 3) is nearly triangular, the 
posterior angle extending on to the narrowed posterior region just referred to. In 
some specimens a small area at the antero-internal angle {me. 2) of this surface is 
marked off from the rest, and indicates that the articulation of the second metacarpal, 
in some cases at least, extended slightly on to the magnum. 
The uneiform (text-fig. 24) is a wedge-shaped bone, the base of the wedge being the 
inner surface articulating with the magnum [mag.), the facet for which is nearly 
flat and extends the whole depth of the bone in front, but is confined to the upper 
