some Remains of Rodeufs. 191 



narrower, so tluit its plan is triangular instead of nearly 

 rectangular. In the beaver the astragalean facette is a 

 circular, rather deep basin, with a well-defined posterior rim, 

 occupying about half of the proximal surface ; in the fossil it 

 is a rather shallow, irregularly shaj)ed concavity, with an 

 ill-detined posterior margin occupying fully two-thirds of the 

 proximal surface. Tiie distal surface presents the usual 

 three facettes for the cuneiforms^ and these have a greater 

 antero-posterior extent than in the beaver. The facette for 

 cuneiform III, is nearly plane instead of concave antero- 

 posteriorly ; that for cuneiform II. is relatively wider and 

 gently convex from behind forwards, instead of nearly fiat. 

 The facette for cujieiform I. is large, crescentic, and concave, 

 forming the anteiior side and roof of a profound notch which 

 cuts almost through the bone from the distal to tiie proximal 

 surface; in the beaver this notch is much less deep and 

 the facette is greatly reduced and convex, only the anterior 

 part of the facette of the fossil being represented. On the 

 other hand, in the beaver the anterior face of tiie greatly 

 developed descending process or "spur " bears a small addi- 

 tional facette for the i)osterior margin of cuneiform I., which 

 is not represt^nted in the fossil. Between the superior border 

 of the chief facette for cuneiform I. and the astragalean 

 surface there is in the beaver a rather large, slightly inclined, 

 oval facette for the '^ navicidare tibude^^ ; in the fossil this 

 facette is also present, but is narrower, triangular in shajie, 

 and highly inclined. The outer (libular) side of the bone is 

 occupied anteriorly by the cuboid facette. In the beaver 

 this IS relatively short, low behind, its plane nearly vertical, 

 and very slightly concave antero-posteriorly. In the fossil 

 it is longer, much higher behind, its nearly vertical anterior 

 portion faces backwards and outwards, and its oblique hinder 

 part faces .slightly forwards, downwards, and outwards; the 

 outer border of the bone, when viewed from below, conse- 

 c^uently appears widely notched instead of straight or gently 

 concave. Tiie posterior spur is much less developed than in 

 the beaver ; in the latter its plan is nearly square, its flat 

 upper surface ascends posteriorly, while below it is produced 

 as a massive projection descending considerably below the 

 general level of the distal surface ; in the fossil it is narrower. 

 Its upper surface is rounded and shelves away behind and 

 laterally, while below the de.scen ling process is little developed 

 and scarcely atUiins the level of the distal surface. Tiie 

 measurements recorded in the following table bring out many 

 important distinctions: — 



