xiii.] THE FROG. 223 



/;. The bone of the forearm. 



a. Hollowed out above to fit the lower end of 

 the humerus. 



/3. Shewing below a tendency to divide into the 

 two bones of which it is made up; viz. the 

 radius and the ulna. When the limb is 

 stretched out at right angles to the body 

 with the pollex forwards, the radius is on the 

 anterior, and the ulna on the posterior side 

 of the axis of the limb. 



c. The carpus. Two bones (a, b) articulate with 

 the ankylosed radius and ulna. A third bone 

 (c\ on the radial side of the carpus, articulates 

 only with the carpal bones on the proximal and 

 distal sides of it. A large bone (d) occupies 

 two-thirds of the ulnar side of the carpus, and 

 articulates with a, b and c on one side, and 

 with the third, fourth and fifth metacarpals on 

 the other. Two small ossicles articulate with 

 the distal face of c and bear the first and second 

 metacarpals. 



d. The digits. 



Five in number, the first (radial one) being, 

 however, rudimentary: beginning at the ulnar 

 side, we find 



a. The fifth digit (that on the outer or ulnar 

 side of the limb) : it presents a cylindrical 

 proximal bone (metacarpat] followed by three 

 others (phalanges), each shorter than its pre- 

 decessor. 



p. The fourth digit : a metacarpal bone and three 

 phalanges. 



