ANATOMY OP THE SHOE-BILL. 



675 



proximal mass of tlie muscle converges to a strong flattened 

 tendon (text-tig. 128, 1), wliicli is inserted to the humerus rather 

 distally and not far from the posterior end of the deltoid inser 

 tion. The more distal portion of the muscle converges to a macK 

 broader tendon, which forms the posterior border of the whole 

 mviscle and then dipping under the first tendon of insertion runs 

 in to the humerus proximally of it (text-fig. 128, 2). There is 

 also a strong anchoi' to the humerus, shown as cut and reflected 

 in the figure (text-fig. 128, 3). 



Text-fio-. 128. 



r^CRo. 



Pectoral muscle of Balceniceps. Tendon dotted ; muscle striped. 



AcRO. Acrocoracoid process. Hu. Humerus. 



Pec. Pectoralis major, cut across. 



1, 2. Insertion tendons of pectoralis to humerus. 3. Anchor to humerus, 



divided and reflected. 

 P.pt. Pectorales propatagiales. 



Su. Tendon of insertion of supracoracoideus (Pect. minor). 

 I)e. Deltoides major. 

 Cor. ex. Coracobracliialis externus. 

 ]J. 1. Tendon of origin of biceps. V>. 2. Cut bell^' of biceps. 



The large area of origin of the great pectoral is of course 

 associated with a powerful wing, and is probably purely adaptive 

 Proc. Zool. Soc— 1913, No. XLY. 45 



