1901.] 



ANATOMY OF GEU1FOKM BIRDS. 



637 



division throughout the greater part of the extent of the muscle, 

 and, save in OaUinulu pKcenicurus and Porzana Carolina, they are 

 actually in continuity. The posterior part, corresponding to the 

 posterior division in most birds, is enormously strong and large, 

 and its origin has spread distally until it has reached a considerable 

 portion of the ilium and the musculature of the thigh. At the 

 insertion, the fleshy and broad insertion of the anterior portion 

 (text-fig. 74. L.A.) is superficial, and its proximal edge is in contact 



Text-fig. 74 



Shoulder-muscles of Rail us longirostris. Shoulder-muscles of Psophia obscura. 

 Musculature of right shoulder, external view. 



2. Tendon of supra-coracoideus A.S. Anconajus scapularis, cut short, 

 and in text-fig. 75, reflected. 8.A. S'capuli-humeralis anterior. 8.P. Scapuli- 

 humeralis posterior. 8. Expansor secundariorum. L.P. Latissimus clorsi 

 posterior. L.P. A. Slip of lat. dorsi post, to anconeus scapularis. L.A. 

 Latissimus clorsi anterior. AM. Auconaeus huuieralis. 8.C. Sub-seapuli- 

 coracoideus. 



S. Humeral anchor of anconseus. .'/. Humeral insertion of lat. dorsi ant. 

 The tendinous areas arc dotted. 



and partly fused with the tendinous insertion of the posterior division 

 (text-fig. 74, ./). The latter runs to the humerus, in close associa- 

 tion with the humeral anchor of the anconseus scapularis (text- 

 tig. 74. ■!). It also sends proximally a remarkable muscular slip 

 (text-fig. 74, L.P. A.) which is fused with the chief origin of the 

 anconseus scapularis. The condition of this muscle offers three 

 points of special note. The great size and backward extension of 

 the muscle with its iliac origin are certainly apocentric. The fusion 

 of the two divisions along a great part of their course, from 

 origin to insertion, is possibly archecentric, and brings to mind 

 the -ingle latissimus dorsi of Aptery.v, a condition possibly arche- 

 centric for Aves, and to he compared with the single muscle in 

 Reptiles. The muscular attachment to the anconseus of the inser- 

 tion of the posterior division possibly is archecentric : in any case 

 the only parallel to it with which I am acquainted is the similar 

 condition described by Furbringer in the ease of Gcuuarhtt. 



In the Oruidee the conditions differ. In the Grruinte the two 

 Pboc. Zool. 8oo.— 1901, Vol, II. No. XIJI. 12 



