BY W. J. S. McKAY. 311 



Echidna. 

 Origin. The subscapulaiis is large and extensive in its 

 origin. It arises from a triangular-sliaped area on the external 

 surface of the scapula. This area is bounded dorsally by the pos- 

 terior tliree-fourths of the outer margin of the vertebral border; 

 anteriorly by the origin of the infraspinatus and upper half of the 

 glenoid ridge with the origin of the long head of the triceps ; 

 posteriorly by the (actual) posterior border. But in addition to 

 this the muscle arises from the (actual) posterior border and the 

 inner face of the scapula immediately adjoining this posterior 

 border ; this latter origin does not, however, reach quite up to the 

 posterior extremity of the vertebral border, nor yet quite down to 

 the coracoid. (Fig. 10, S. Sc). 



Insertion. The muscle, triangular in outline and very 

 bulky, runs downwards, backwards and somewhat inwards, to 

 become inserted by a tendon on the ventral surface and antero- 

 intenial border of the lesser tuberosity. 



Relations. The muscle at its origin is partially hidden 

 from view by the posterior part of the trapezius, and the dermo- 

 dorsi cervicalis. Posteriorly it is related to the teres major and a 

 slip to the latissimus from the scapula ; while that portion of its 

 origin that extends round from the (actual) posterior border to 

 the inner face of the scapula comes into relation with the inser- 

 tion of the serratus magnus and origin of the omo-hyoid and 

 supraspinatus. At its insertion the muscle is close to the 

 epicoraco-brachialis and the teres minor, inserted distally on the 

 posterior face of the humerus adjoining the lesser tuberosity. 



Ornithorhy-N-chus. (Fig. 12, S. Sc). 



The subscapularis has a very extensive origin from both 

 the external and internal faces of the scapula. It arises from a 

 triangular-shaped surface on the external face of the bone. This 

 is bounded dorsally by the origin of the teres major from the 

 posterior one-third of the vertebral border, and by that portion of 

 the vertebral border between the origin of the teres major and the 



