8ff STRUCTURE AND CLASSIFICATION OF BIEDS 



ulna to be inserted on to the great tuberosity of the ulnar 

 carpal bone. A thin muscle arising from it passes into a 

 tendon which is connected with the secondary feathers. 

 The above refers to Palamcdea. In penguins the entire 

 muscle is represented by a tendon only. 



Extensor Digitorum Corn-inn nis. Arises from the external 

 condyle of humerus. It splits on the hand into two tendons, 

 of which one is inserted on to the basis of the first phalanx 

 of digit I., the other on to the corresponding phalanx of 

 digit II. In Struthio the first of the two tendons is wanting. 

 In the penguins the muscle is represented only by a tendon 

 which is inserted on to the outer side of metacarpale II. and 

 on to the basis of the first phalanx of that digit. 



Extensor Longus PoHicis. This muscle arises from the 

 proximal region of both radius and ulna. The common 

 tendon is inserted on to the origin of metacarpale I. 



Extensor Indicis Longus. This muscle is two-headed. 

 The longer head arises from the radius from its middle two- 

 thirds, bat sometimes also receives a few fibres from the 

 ulna ; the second much shorter head springs either from the 

 distal end of the radius or from the os carpi radiale, or 

 finally from the basis of metacarpale II. ; the united tendons 

 are inserted on to the head of the first and the basis of the 

 second phalanx of digit II. The second head is absent in 

 Fulica and in some other birds. 



Interosscus Dorsalis. This muscle arises fleshily from 

 the opposed surfaces of metacarpals II. and III. The 

 common tendon is inserted on to the base of the second 

 phalanx of the second digit. 



Interosseus Palmar is. Has an origin from the same 

 metacarpals as the last and is inserted on to the first phalanx 

 of digit II. 



Ulni-metacarpalis Ventral is. It arises fleshily from the 

 radial face of the last quarter of the ulna, and is inserted on 

 to the head of the first metacarpal. 



Ulni-metacarpalis Dorsalis. SFhis springs by a tendon 

 from the distal region of the ulna, and has an insertion upon 

 the third metacarpal. 



