MUSCULAR SYSTEM OF AVES. 99 



the phalanx of the thumb immediately beyond the tendon of the 

 preceding muscle. The two tendons are quite distinct from one 

 another in the birds of prey, the Ostrich and Parrots, but unite 

 at the lower end of the fore-arm in the Anatidcs, PhasianidcE, and 

 Grid dee. 



The extensor carpi ulnaris. ib. 34, comes off from the inferior 

 extremity of the outer condyle of the humerus, passes along the 

 middle of the exterior surface of the fore-arm, and its tendon, 

 after passing through a pulley at the distal end of the ulna, is 

 inserted into the ulnar phalanx. It draws the hand toward the 

 ulnar edge of the fore-arm, and is the principal abductor or folder 

 of the pinion. 



The flexor metacarpi radialis, ib. 35, is a short and weak 

 muscle, which arises from the inferior part of the ulna, descends 

 along the internal side of that bone, winds round its lower extre- 

 mity and the radial edge of the carpus, passes beneath the tendon 

 of the radial extensors, and is inserted, external to the latter, 

 high up into the dorsal aspect of the radial phalanx of the meta- 

 carpus. In the Ostrich it arises from the lower third of the 

 ulna. In the Peno-uin it is wantino;. 



The flexor metacarpi ulnaris, ib. 36, arises beneath the fore- 

 arm 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. 



The muscles of the pinion or hand are few, and very distinct 

 from one another ; the index or spurious wing is moved by four 

 small muscles, viz. two extensors, an abductor, which draws the 

 digit forward, and an adductor. The middle digit receives three 

 short muscles, two of which are extensors, and the third an 

 abductor ; in this action it is aided by one and opposed by another 

 of the extensors. The outer digit receives an abductor, which 

 comes from the ulnar edge of the preceding phalanx. 



§ 134. Muscles of the Legs. — The muscles of the pelvic limb are 

 here described chiefly as they exist in the Apteryx, in which they 

 present their full developement. The most superficial of the 

 muscles on the outer side of the leg is that very broad one which 

 combines the functions of the tensor vaginai and rectus femor is, but 

 which, in the opinion of Cuvier^ and Meckel,^ is the homologue 

 of the tensor vagijicc and glutcBus maximus (seu externus) : since, 



^ XII'. torn. i. p. 502. 2 xlvi*. th. iii. p. 361. 



H 2 



