820 



caneal convexity is larger ; the intervening groove is narrower and deeper : the scaphoid 

 tuberosity is larger in proportion to the body of the bone, and the part supporting it is 

 thicker and shorter. 



5266. The right calcaneum. 



The superiority of size is still greater in this bone as compared with that in the Chimpanzee, 

 and is principally due to the greater expansion and production of the posterior tuberosity, 

 which expands instead of contracting towards the sole. The broad, rough, flattened, inferior 

 surface of the Human calcaneum offers a marked contrast with the smooth narrow concavity 

 of the same part in the Chimpanzee, and obviously relates to the plantigrade character of Man. 

 All the articular surfaces, but especially the cuboidal one, are larger in Man. The promi- 

 nence supporting the inner astragalar surface is less produced, and the groove for the flexor 

 tendons is wider and shallower in Man : the external tuberosity, especially, is much more 

 feebly developed, and less defined, than in the Chimpanzee. 



5267. The right naviculare. 



This is shorter transversely, its increase of size being a little in depth, but chiefly in antero- 

 posterior extent, and this more manifestly at the outer than the inner side, whence results a 

 more vertical position of the cuneiform facets, which are flatter and more nearly upon the 

 same plane, than in the Chimpanzee. The surface for the cuboid is shorter and broader, 

 although it extends across only half that end of the naviculare, instead of across the whole, 

 and joining the astragalar concavity, as in the Chimpanzee. The internal tuberosity is, how- 

 ever, less produced than in the Chimpanzee. 



5268. The right entocuneiform, or ' os cuneiforme internum.' 



This is larger than in the Chimpanzee, and presents a smaller and flatter facet to the 

 naviculare and a smaller facet for the second metatarsal, which, also, is distinct from the sur- 

 face for the mesocuneiform, instead of being confluent therewith, as in the Chimpanzee. But 

 the most characteristic difference between the entocuneiform of Man and the Chimpanzee is 

 seen in the shape of the surface for the metatarsal of the hallux, which is flat hi Man, but is 

 convex transversely in the ape, to allow of the free movements of approximation and separa- 

 tion of that toe from the rest, required by its function as a thumb in the act of grasping and 

 climbing. . 



5269. The right mesocuneiform, or ' os cuneiforme medium.' 



This bone is larger than in the Chimpanzee, especially in depth : the upper surface is 

 nearly as flat ; the surface for the entocuneiform is divided by a vertical groove ; that for the 

 ectocuneiform extends across the whole of the upper half of the outer surface in the Chim- 

 panzee, but in Man .is limited to the posterior half of the same surface. 



