94 - Bulletin American Museum of Natural History. © [Vol. XXXIV, 
therium and Mesonyz. The trapezium and entocuneiform are reduced to 
about the same extent, and as in those genera have small facets for the first 
digit, which in the hind foot is clearly a small nodule indicated by a pit for 
its reception on mt. II. In the fore foot the pollex was probably also a 
vestigial nodule, as the facet for its articulation on the trapezium is quite 
small. The second metacarpal has much heavier shaft than the third or 
fourth, while the fifth is decidedly shorter than the fourth with about the 
Fig. 82. Pachyena ossifraga, fore-foot bones, natural size, a, proximal view of manus, 
6, inner view, c, distal view of trapezium showing the small facet for vestigial pollex. From 
skeleton No. 16154, Gray Bull beds of Big Horn Basin. 
same weight of shaft. In the hind foot the fifth digit is much smaller than 
the others, but its length is not preserved, the second has a somewhat 
heavier shaft than the third and fourth. The distal ends of the metapodials 
and the phalanges show the same features as Mesonyx. The most obvious 
primitive character is the relative shortness and breadth of the astragalus 
and flatness of its trochlea. 
° 
