HYEACHYUS. 667 



The extremity bears two facets, the larger for the cuneiform, the smaller 

 for the pisiform bone. 



The radius is throughout its length a stouter bone than the ulna, and 

 bears much the greater part of the carpal articulation, viz, with the scaph- 

 oid, lunar, and part of the cuneiform bones. This articulation is transverse 

 to that of the ulna, which is thus at one side of and behind it. The head 

 is a transverse oval in section, the narrower end outward. The articular 

 face consists of one and a half trochlese, the latter wider and internal. The 

 shaft is a transverse oval in section, with an angular ridge along the middle 

 externally, and the distal part proximally. A broad groove marks the 

 upper face of the epiphysis, where the shaft has a vertical inner face. 



Measurements. 



M. 



Length humerus (axial) 0.270 



Diameter head to bicipital groove •.... 037 



Length along crest outer tuberosity (about) 052 



Transverse diameter, distally O'*^ 



Anteroposterior diameter of inner condyle 042 



Width olecrauar fossa 020 



Length ulna '-^60 



Depth olecranon distally 027 



Depth at coronoid process "25 



Depth of distal end 019 



Depth at middle shaft 019 



Length radius .- 200 



Width of head 036 



Depth of head 021 



Width shaft at middle 021 



Width near distal end (greatest) 037 



Width distal articulation 030 



The elements of the carpus are distinguished for length, and for reduc- 

 tion of width. The anterior faces of all are considerably longer than broad, 

 but the longest faces of the cuneiform, scaphoid, and trapezoides are antero- 

 posterior. The facets are as usual in the carpus; scaphoid ^; lunar J; 

 cuneiform |; trapezium \; trapezoides j; magnum |; unciform |. The 

 cuneiform has a rather L-shaped external face, its ulnar face being strongly 

 excavated in correspondence with the angular extremity of the ulna. This 

 peculiarity is not seen in Hyracotkeriwm venticolum and Triplopus cuhitalis. 

 The pisiform has two proximal facets, and is enlarged and thickened dis- 

 tally; pressed inward, it reaches the scaphoid. The trapezium is a small 



