70 THE MYOLOGY OF THE RAVEX. 



of the system in a Eaven, both as regards weight and 

 general bulk. It arises from the posterior moiety of the 

 anterior surface of the sternal body, to the extent shown 

 in Fig. 25 ; from the entire marginal third of the corre- 

 sponding aspect of the keel, as seen in Fig. 24 ; and 

 finally from the entire outer side of the corresponding 

 clavicular limb of the furcula, as indicated in Fig. 8. 

 The fibres from this extensive origin converge, with but 



o o 



little tendency to overlap as we find them in man, 

 toward the proximal third of the humerus of the same 

 side, into which they are inserted by a broad tendon 

 occupying the entire surface of the palmar aspect of the 

 pectoral crest. The posterior surface of the pectoralis 

 major is far more tendinous in structure than its anterior, 

 and as it passes over the shoulder-joint this tendinous 

 portion becomes intimately blended with the long head 

 of the biceps, while near this point it also receives the 

 insertion of the dermo-humeralis (No. 12), the fan-like 

 tendon of the latter blending with the broad tendon of 

 the pectoralis. 



In the sternal region the pectoralis major completely 

 covers the other two pectoral muscles which arise from 

 the sternal body. 



This muscle when contracting depresses the humerus 

 with great force, and consequently the wing of the bird, 

 and so forms the chief agent of flight. 



In describing the pectoralis major for birds in general, 

 Sir Richard Owen says that " This muscle is very long 



Ohne Namen erwahnt. Schopss, p. 112. 

 Dermo-humeralis. Owen, p. 24. 



Panniculus carnosis (second portion). Eeid, p. 139. 

 Muscle des parures. Gervais et Alix ; Alix, p. 401. 



,, ,, Watson, p. 81." 



[See the present writer's description of the dermo-humeralis in 

 the present connection.] 



