MUSCLES OF THE FUIJE LIMB 89 



Extensor Mc'tacar/ti Ulnaris. Springs from the external 

 condyle of the humerus. There is generally a second head, 

 which, instead of being tendinous, is fleshy and rises from 

 the humerus a little below the first head. The tendons in 

 which the two end do not join until a little before their 

 insertion 011 to the base of the metacarpal of digit I. The 

 degree of separation of the two heads differs considerably. 

 In the penguins only one head is present. 



Flexor Digitoruin Sublimix. From the internal condyle 

 of humerus to os carpi ulnare is a strong aponeurotic fascia, 

 from the distal end of which springs the muscle in question, 

 to be inserted on to phalanx I. of digit II. In Palamcdea Mr. 

 MITCHELL and I traced the tendon to the base of the second 

 phalanx of the same digit. In Psittacus and Columba the 

 tendon has the same extension. In Struthio the muscle is 

 entirely absent. 



Flexor Digitoruin Profundus. This springs from the 

 middle and proximal third of the ulna, and is inserted on to 

 the basis of the second phalanx of the second digit. In 

 Corvus, &c., the muscle is two-headed, the two heads being 

 separated by the insertion of the brachialis interims. In 

 other birds the extent of the origin varies. 



Abductor Indicis. From metacarpal Il.tobasisof phalanx 

 I. of digit II. In Palamcdea it also arises from the flexor 

 pollicis. 



Flexor Pollicis. From metacarpal I. to thumb phalanx. 

 In Palamcdea its fleshy belly gives rise to a slip which passes 

 to the abductor indicis. 



Adductor Pollicis. In Palamedca it arises from the meta- 

 carpal just beyond the articulation of the thumb ; it ends 

 in the ala spuria and not on the thumb bone. In some 

 birds it has also a connection with the thumb bone. 



Extensor Pollicis Brevis. This muscle arises fleshily from 

 the second metacarpal. It is inserted on to the phalanx of 

 the thumb. 



Abductor Pollicis. This muscle arises from metacarpal I. 

 and passes to phalanx of same digit. 



