144 THE MYOLOGY OF THE RAVEN. 



flexor digitorum profundus. Owen calls this muscle the 

 flexor metacarpi idnaris, and says of it in the Apteryx 

 that it " arises beneath the forearm from the internal 

 pulley of the ulna ; continues fleshy to the pinion ; and 

 is inserted, first into the ulnar carpal bone, then into the 

 ulnar phalanx. The latter insertion is wanting both in 

 the Ostrich and Penguin " (Anat. Verts., vol. ii. p. 99). 



When we come to examine it carefully in the Raven, 

 especially the distinctness of its external head, and a 

 median fascia that runs longitudinally through its belly, 

 and finally its distal tendinous offshoot, it is not difficult 

 for us to imagine that the muscle originally was com- 

 posed of two parts, or perhaps two distinct muscles 

 (Figs. 31 and 36). 



84. The flexor carpi idnaris brevior 1 is a muscle 

 that I do not find described in any work at present 

 available to me, and which I here provisionally bestow 

 this name upon in view of the fact that the flexor carpi 

 idnaris is often split up into several portions in some 

 other vertebrates, and this is more than likely an in- 

 stance of it. And then, again, I was influenced in my 

 decision from the additional fact that in its action it 

 assumes in part the function of the flexor carpi idnaris 

 in those animals where it does occur normally. The 

 flexor carpi ulnaris brevior in the Raven, however, not 

 only to a limited extent flexes the hand upon the fore- 

 arm, but by its peculiar carpal insertion rotates the hand 

 towards the side of the body a very important action 

 during flight. 



This muscle arises from quite a broad area covering 

 the middle third of the upper side of the shaft of the 



1 From Gadow's account (foe. cit., p. 272) I would say that this 

 muscle was represented by his No. 86. M. ULNI-METACARPALIS VEN- 

 TRALIS the adductor metacarpi of Schopss and of Watson. 



