393 



roughest, flattened side, or "sole," being below (fig. 7 c); the two broader, smoother 

 concave sides converge to the superior or anterior rounded angle (fig. 6, b) : the free end 

 is due to a tuberous epiphysis (a) with an upper smooth bursal surface on the terminal 

 facet. The upper angle (fig. 6, b) expands to the anterior articular or tarsal portion of 

 the bone, which is more abruptly enlarged, and especially to the outer side : this sup- 

 ports the subconvex articular surface (d) for the external malleolus formed by the distal 

 epiphysis of the fibula (PI. LXXIV. fig. 8, b). The upper surface of the expansion 

 supports the convex surface (i) for the articulation (i) of the astragalus (fig. 4). The 

 upper and inner rising is divided into a small anterior smooth articular surface (fig. 6, 

 k) for that marked k in the astragalus (fig. 4), and a posterior, chiefly roughened, 

 surface (h) for syndesmosis with the apical part of the astragalus (fig. 4, h). In advance 

 of the astragalar expansion the calcaneum, somewhat contracted, extends, and terminates 

 in the large subtriangular vertical surface for the " cu- 

 bo'ides." The outer half of this surface (fig. 8, e) is more 

 produced than the inner one (ib. f), and is continued 

 into the lower or apical part (ib. g) of the cuboidal facet. 

 The astragalar expansion (figs. 6, 7, d, n, e) overhangs the 

 lateral concave surface on both sides of the bone, but 

 most so on the outer one (fig. 2), which develops two 

 tuberosities (fig. 7, n, n'). 



The inner production has more vertical extent, and is 

 impressed by a longitudinal channel : it supports the sur- 

 face (fig. 6, I) for that so marked on the navicular part of 

 the astragalus (fig. 4). The ridges, so formed (figs. 1 & 2, 

 m, n'), afford fulcral resistance to the strong tendons gli- 

 ding along the concave channels (ib. b, b') from the leg to 

 the foot beneath them. A well-marked groove (fig. 7, o) 

 divides the fore part of the " sole " of the calcaneum from 

 the apical part of the cuboidal articular facet (e,f). 



The navicular (fig. 1, n) is a small, oblong, subqua- 

 drate, compressed bone, presenting a narrow concavity 

 to the facet (f) of the astragalus (figs. 4, 5), and an ob- 

 long undulate surface divided between the proximal ones 

 of the ento- (c i) and the ecto- (c e) cuneiform bones. 



The entocuneiform (cut, Fig. 1, ci) is an oblong flat- 

 tened bone notched at its hind margin. It is pushed 

 inward and backward, articulates by its upper (proximal) end or surface with the navi- 

 culare, by the inner surface of its proximal part with the ectocuneiform (ce) which it 

 overlaps, by its anterior border and contiguous inner surface of its distal half with the 

 mesocuneiform (cm), and by its distal end with the major part of the proximal articular 

 end of the metatarsal (n). 



Parts of tarsus and metatarsus, 



Macropus major. 



