OSTEOLOGY AND ARTHROLOGY 51 



flattened on its anterior surface, and presents at this level 

 a slight depression which corresponds to a small eminence 

 on the anterior aspect of the superior extremity of the 

 radius. The surface which articulates with the ulna, viewed 

 on its anterior aspect, has the shape of a slightly-marked 

 trochlea ; except at the level of the internal lip, which, as 

 in man, descends lower than the surface for articulation 

 with the radius (condyle). Behind, the trochlea is more 

 clearly defined. 



The bear possesses a considerable power of rotation of 

 the radius ; the bones of the forearm are joined only at 

 their extremities, while in the remainder of their extent 

 they are widely separated. The ulna terminates below in 

 a head and a styloid process ; these articulate with the two 

 last bones of the first row of the carpus — viz., the cunei- 

 form and pisiform. The bones of the carpus are seven 

 in number, the scaphoid and the semilunar being fused 

 together. 



The metacarpals, five in number, differ very little from 

 one another in regard to length, though they increase in 

 size from the first to the fifth ; this may be demonstrated 

 by looking at the palmar surface of the hand. It is the 

 reverse of that which we find in man, for the fifth meta- 

 carpal is the thickest of all, and the first is the most 

 slender. 



At the level of each metacarpo-phalangeal articulation 

 are two sesamoid bones. 



The third digit is the longest. The terminal phalanges 

 present two very different portions : one, the anterior, is 

 curved and pointed ; it serves to support the nail, whose 

 shape it assumes ; the other, posterior, forms a sort of 

 sheath into which the base of the nail is received. 



The inferior portion of the posterior surface of this latter 

 part articulates with the second phalanx in the case of 

 each of the last four digits, but with the first phalanx in 

 the case of the thumb. 



Digitigrades : Cat, Dog (Fig. 34).— In these animals the 

 anterior (cervical) border of the scapula is convex ; the 

 posterior (axillary) border is straight or slightly concave. 



4—2 



