THE FOKE LLA1B8. 97 



This articulation presents a striking difterence in direction from that 

 seen in the corresponding face on the ulna of the elephant and mastodon. 

 It is so placed on the shaft of the bone as to look almost directly forward, 

 and only very slightly upward, instead of looking nearly upward, as in the 

 mastodon. It forms, comparatively, a much smaller part of the face for 

 the humeral trochlea. 



In shape, this articulation is distinctly tri-lobate. One rounded lobe, 

 convex from side to side, runs backward and upward to the summit 

 of the beak of the olecranon. A second, and Large lobe, moderately 

 concave in both directions, runs inward, articulating with the ulnar portion 

 of the trochlea of the humerus. An outer, small and flattened, lobe 

 articulates with the ]iosterior part of the radial surface of the trochlea. 

 The front, or lower, outline of the articular face is moderately concave, 

 and adapted to the surface of the radius by a narrow face, becoming wider 

 toward each extremity. 



The distal end of the ulna is terminated by an articular surface, which 

 is somewhat quadrant-shaped. The inner and })Osterior outlines are 

 nearly sti'aight, and meet at a right angle, while the anterior and outer 

 margins are formed by a curved line. 



This face is convex in an antero-posterior direction, strongly so behind. 

 In a transverse direction, it is moderately concave, except near the inner 

 edge, where it is broadly beveled olf, for union with the lunar bone of 

 the carpus. 



Much the larger part of the distal articular face of the ulna articulated, 

 during life, with the pyramidal bone, or the cuneiform bone of man\ 

 anatomists. 



Posteriorly, a surface was presented for the pisiform, and, on the 

 inner side, a narrow beveled surface united with the liuiar bone. 



Farther within, and on the surface of the shaft of the bone, a small 

 surface was presented to the radius, although the two bones, as ah-eady 

 stated, were strongly iixed, during life, in their relation to each other. 

 13 ^ 



