46 



TEETIAET VERTEBRA TA OF THE EATtlM. 



half at the back. The proximal surface for the cuneiform (cu.) is concave antero- 

 posteriorly and convex from side to side. Distally the bone bears two large surfaces 

 for the fourth and fifth metacarpals, and a much smaller inner surface for the outer 

 facet of the slightly displaced third metacarpal. The surface for the fourth 

 metacarpal is somewhat concave and looks directly downwards ; that for the fifth is 

 convex and looks downwards and outwards, almost joining that for the cuneiform 

 externally, making with it the acute angle which is the thin edge of the wedge. 

 The bone is deeper posteriorly than anteriorly. 



The metacarpals (text-fig. 19, p. 40) were short and stout and much enlarged at their 

 articulations. The first is unknown, but, judging from the size of the distal articulation 

 of the scaphoid, probably little reduction had taken place on this side of the foot. 



mcs. 



Left unciform of Arsmoithernim zitteli : A, from above ; B, from below; C, inner (preaxial) face. 



cu., facet for cuneiform ; mag., facet for magnum ; mc. 3, mc. 4, mc. 5, facets for the third, 



fourth, and fifth metacarpals. | nat. size. 



The second is likewise unknown, but it had on its postaxial side a small surface for 

 articulation with the magnum, as is shown by the presence of the corresponding facet 

 on that bone. The third articulated mainly with the magnum, but had a slight 

 overlap on the unciform at least anteriorly. The fourth and fifth articulated with 

 the unciform, and in some cases {e. g., C, 7968) the fifth seems also to have had a 

 surface of contact with the cuneiform (text-fig. 25, cu.). The posterior face of the 

 upper end of the metacarpals seems in all cases to be produced backwards into a 

 strong roughened prominence. 



