COMMON PIGEON. 267 



proximal lip of the cup-shaped pneumatic cavity of the humerus. The 

 opposite lip of this cavity receives the tendon of the teres major /; and from 

 the triangular space between the muscular bellies of these two muscles, the 

 subscapularis muscle, together with the upper portion of the scapula, and 

 a small muscle, the serratus anticus, which passes between the fibres of the 

 subscapularis to be inserted into the inferior edge of the scapula, have been 

 removed. 



v. Coracobrachialis superior, a bicipital muscle with a very extensive origin; 

 arising, superiorly, from the inner surface of the vertebral end of the 

 clavicle ; inferiorly, from a facet on the lateral aspect of the upper surface 

 of the sternal rostrum; and between these two points of origin from the 

 upper and inner surface of the ligament connecting the coracoid, clavicles, and 

 sternal rostrum. Its tendon, which is joined by that of the subscapularis, 

 is inserted proximally and anteriorly to that of the preceding muscle u. 



iv. One head of the extensor plicae alaris anterioris longus, arising from the upper 

 end of the clavicle in continuity externally with a head of the extensor brevis. 

 These muscular bellies appear to be divarications of the deltoid. 



wi. Muscle in connection with the long alar extensor tendons. Its fibres have 

 in the natural condition of the parts much the same direction as those of the 

 muscle w and of the deltoid ; but its origin is mainly from the fascia which 

 covers the biceps in front, and being interposed between that muscle and 

 the tendon of the great pectoral, it is continued up into the tendinous 

 expansion by which the posterior layer of the tendon of the great pectoral 

 connects itself more or less intimately with the coracoid head of the biceps 

 and obtains an insertion into that bone. The muscle wi is inserted mainly 

 into the inner of the two tendons at its distal extremity. This tendon is 

 prolonged down to be inserted into the radial process of the carpo-metacarpal 

 bone which carries the pollex. It is more or less intimately connected with 

 the two other long extensor tendons from the muscle w and from the great 

 pectoral, which are here drawn as one ; as also with the extensor brevis 

 which is not shown in this figure. 



x. Tendon of great pectoral muscle turned back. The posterior portion of this 

 tendon receives at its lower edge the tendon of a cutaneous muscle which 

 is figured as attached to its outer angle, and higher up it receives the main 

 tendon of origin of muscle wi, and is ultimately prolonged either separately 

 or in connection with the tendon of the biceps up to the coracoid. 



xi. Biceps. Its tendon is seen running upwards to be inserted into the internal 

 anterior process of the upper end of the coracoid ; it has a small insertion 

 into the humerus also, which is not shown here. 



