814 



5224. The left radius. 



It is straighter and less expanded at its distal end than in the Chimpanzee. The margin 

 of the circular proximal articulation is less obtuse, but at the same time less produced, so 

 that what may be called the neck of the bone which intervenes between this surface and the 

 bicipital tuberosity is less defined : it is thicker and shorter, and is more in a line with the 

 shaft of the bone, in Man. The depression for the ' extensor digitorum ' is less deep, the 

 bounding ridges being less developed in Man ; and the same may be said of the contiguous 

 grooves for the extensors of the thumb and index finger. The tuberosity for the insertion of 

 the great supinator muscle is less developed. The radial end of the distal articular surface 

 is narrower ; but in the form of the surface for the ulna and the prominence of the anterior 

 angle, the Chimpanzee comes nearer to Man than the Orang does. 



5225. The left ulna. 



It closely corresponds in length and general proportions with that of the Chimpanzee, but 

 its distal half is somewhat more slender. The ulnar boundary of the great sigmoid cavity is 

 interrupted by a deeper groove, but not to the same extent as in the Chimpanzee : the radial 

 side of the sigmoid cavity extends, as in the Chimpanzee, to the back part of the olecranon. 

 The lesser sigmoid cavity is transversely oblong, not produced downwards into the semicircular 

 form ; it also extends to the posterior surface of the ulna, which is not the case in the Chim- 

 panzee. That surface is broader and less convex along the proximal half of the ulna than in 

 the Chimpanzee. The ridge and fossa for the origin of the flexor profundus are less sharply 

 defined and are shorter than in the Chimpanzee. The interosseous angle is much better 

 marked along the middle of the shaft of the bone ; but this part is straighter in Man, not 

 bent forwards as in the Chimpanzee. The antero-posterior diameter of the distal end is less 

 in proportion to the transverse, and the groove between the radial tubercle and styloid pro- 

 cess is less marked. 



5226. The right humerus. 5227. The right radius. 



5228. The right ulna. 



5229. The right scaphoides. 



It is smaller than that of the Chimpanzee, and its convex side is more equally divided by 

 a constriction into the radial and trapezial portions. The radial portion is a triangular con- 

 vexity with the angle rounded off, and forms an obtuse angle with the trapezial convexity, 

 which is ovate : they are divided by a broader tract than in the Chimpanzee. The obtuse 

 ulnar angle is much less produced : the concavity for the magnum is deeper and better 

 defined than in the Chimpanzee. 



