THE FORE FEET. 



115 



The proximal surface of the magnum (figure 5), by which it bears 

 upon the scaphoid and lunar bones, is much elevated posteriorly in the 

 region of the face for the lunar, but the two facets are so perfectly 

 confluent as scarcely to be distinguished. The face for the scaphoid is 

 strongly saddle-shaped, and does not extend quite to the anterior margin 

 or the bone. 



The face for the lunar is nearly flat, or slightly convex from side 

 to side, sigmoid from before backward, and is carried well over to the 

 posterior face of the bone. The variation in the form of this curve is 

 considerable, but the specimen figured on the Plate may be regarded as a 

 fair average, while extreme forms are represented in woodcuts 121 and 

 122, below. 



Figure 121. — Right magnum of DinoCKias mirabile, Marsh (No. 1211); side view. 

 FiGCKE 122. — 'Right magnum oi Dinoceras miraiile, {So. 1230); side view. 



/. face for lunar; mcIII. face for third metacarpal; un. face for unciform. 

 Both figures are one-half natural size. 



The distal face of the magnum (Plate XXXIV, figure 6) is mostly 

 occupied by an elongated articular face for the support, in great part, of 

 the third metacarpal. This face is more or less moderately concave from 

 before backward, slightly convex transversely, and is usually a little 

 broader in front than behind. It is separated by a rounded ridge from the 

 confluent, narrower and oblique, face lying along its radial side, and 

 aiding in the support of the second metacarpal. 



The dimensions of the magnum bone of four individuals of the 

 Dinocerata are as follows : 



