THE FOEE-LIMB. 317 



3. The wrist. In the rabbit the wrist or carpus consists 

 of nine small bones, of which one, the pisiform, is 

 commonly regarded as a sesamoid bone or ossifica- 

 tion in the tendon of a muscle, but by some anato- 

 mists is considered to be a vestige of a sixth digit. 

 The arrangement of the remaining eight can best be 

 understood by comparison with more primitive, types. 

 The typical carpus consists of nine bones, arranged 

 in a proximal row of three, articulating with the 

 radius and ulna ; a distal row of five, each of which 

 supports one of the digits ; and a central bone wedged 

 in between the proximal and distal rows. In the 

 rabbit the arrangement is as follows. 



a. The proximal row of earpals consists of the three 



typical bones. 



i. The radiale, or scaphoid, is on the inner or pre- 

 axial side, and articulates with the radius. 



ii. The intermedium, or semilunar, is the middle 

 bone of the three, and articulates with the 

 radius. 



iii. The ulnare, or cuneiform, is the outer or post- 

 axial bone of the proximal row, and articu- 

 lates with the" ulna. 



b. The central bone. 



i. The centrals is a small bone, articulating with 

 the distal surfaces of the intermedium and 

 radiale, and appearing to belong to the distal 

 row of earpals. 



c. The distal row of earpals consists of four bones, 



the two outermost of the typical carpus having 

 fused to form a single bone. 



i. The first carpale, or trapezium, is on the inner or 

 preaxial side of the wrist ; it articulates with 

 the radiale, and supports the first metacarpal. 



ii. The second carpale, or trapezoid, articulates 



