Scott.] ^^^ [May 18, 



is a small nodular bone, which is attached to the scaphoid and trapezoid, 

 but lias no facet for a first metacarpal. In view of the fact, indicated by 

 Osborn and Wortman, and confirmed by one of the specimens received 

 from Mr. Hatcher, that a hallux was present in the pes, the absence of the 

 pollex, which is preserved in at least two oreodonts, is decidedly unex- 

 pected. There is reason to believe, however, that the pollex was retained 

 in A. antiquus. The trapezoid is considerably larger than the magnum, 

 especially its dorsal portion ; posteriorly it is excavated on the ulnar side 

 for the extension of the magnum. The surface for the scaphoid is some- 

 what warped ; broad and proximal in front, narrower and obliquely lateral 

 behind. The distal portion of the trapezoid articulates only with the second 

 metacarpal. The magnum differs from that of Oreodon in several im- 

 portant respects. Its proximal surface is occupied principally by the 

 lunar, the scaphoid being confined to a relatively narrow surface in front, 

 though posteriorly the contact is more considerable, and further the 

 magnum has but a very small facet for the second metacarpal. The unci- 

 form differs considerably from that of Oreodon. Anteriorly the lunar 

 facet forms an excavation upon the radial side of the bone, but posteriorly 

 an almost cylindrical process extends beneath the lunar. The proximal 

 surface, which in Oreodon is divided equallj'^ between the lunar and cunei- 

 form facets, is occupied almost entirely by the facet for the cuneiform. 

 The articular surface for the fifth metacarpal differs from that of the last- 

 named genus in its larger relative size and more distal position, and the 

 posterior hook of the unciform is decidedly more massive. 



The metacarpals are represented by the proximal and distal ends of the 

 second and fourth and by the third complete. They display several signifi- 

 cant difl^erences from those of Oreodon. As already mentioned, the pollex 

 was probably entirely absent and the other metacarpals are of more uni- 

 form size, giving a more isodactyl form of manus than in Oreodon. The 

 head of mc. ii is slightly smaller than that of mc. iv, and has a large con- 

 cave facet for the trapezoid and a very minute one for the magnum. The 

 shaft is more rounded and less antero posteriorly compressed than in 

 Oreodon. The distal end is creodont rather than ungulate in appearance. 

 This appearance is due to the great enlargement of the processes for 

 attachment of the lateral ligaments, the more distinct constriction of the 

 trochlea and its almost spherical shape and to the greater prominence of the 

 carina. Mc. iii is the heaviest of the series ; it bears a large facet for the 

 magnum, which is convex antero-posteriorly and concave transversely, 

 and abuts against the unciform by a process which overlaps the head of 

 mc. IV ; this process is, however, relatively smaller than in Oreodon. 

 Mc. IV requires no particular description ; it is rather smaller than mc. iii 

 and somewhat larger than mc. ir. 



The phalanges are, at first sight, very different from those of Oreodon, but 

 a careful comparison shows important resemblances, especially if the small 

 species, A. antiquus, from the lower beds be considered. In the proximal 

 phalanx the following differences from Oreodon may be observed : (1) 



