MYOLOGY OP OPISTHOCOMUS CEISTATUS. 357 



to the costo-coracoid membrane against which it is immediately applied. It is expanded 

 and rounded at its distal extremity, corresponding to the club-shaped lateral extremity 

 of the sternum between the incurvated great pectoral origin. Its tendon of insertion 

 commences on the coracoid, and plays over it in a pulley-like fashion, crosses the head 

 of the humerus to a prominent ridge on the middle of the dorsal surface, immediately 

 above the articular facet on the summit of the great tuberosity of the humerus. 



The 3rd pectoral has its usual origin. It is moderately well developed. It runs 

 almost parallel with the coracoid, crosses behind the coraco-brachialis ; its tendon of 

 insertion glides over the pulley-like summit of the ulnar tuberosity of the humerus to 

 be inserted into a depression immediately below the tuberosity, and below the insertion 

 of the teres major, the latter muscle crossing it obliquely. This muscle and the 

 coraco-brachialis cover the axillary space, and are applied directly against the axillary 

 vessels and nerves. 



The coraco-brachialis is inserted into the summit of the inner tuberosity of the 

 humerus by a short slender tendon, which joins with that of the subscapularis. 



The subscajmlaris arises from the anterior two-thirds of the ventral surface of the 

 scapula ; it is a triangular-shaped muscle, and rapidly converges towards its insertional 

 tendon. It is crossed by the coraco-brachialis and the 3rd pectoral. The tendon of 

 the latter muscle lies imbedded in the muscular fibres of the subscapularis, but does not 

 divide it into two parts, as described by Owen in other birds. 



Depressor coracoideus and costo-scapularis are closely associated at their origin, arising 

 as a broad, but thin, muscular band from the anterior external angle of sternum, and 

 1st sternal rib as far as its angle. The muscle then divides into two portions — the 

 coracoid factor passing obliquely upwards, forwards, and outwards, to be inserted into 

 the sternal 3rd of the coracoid, its lower border and posterior surface ; the scapular 

 factor is slender and elongated, and passes horizontally outwards, terminating in a short 

 flattened tendon, which is inserted into the ventral border of the scapula about half an 

 inch posterior to its articular extremity. The subscapularis muscle lies in front and 

 partially conceals it. It is applied for half its length against the 1st vertebral rib. 



Teres major, large, fleshy, and wedge-shaped, arises from the anterior border of the 

 lower half of the scapula, and from the posterior two thirds of its dorsal aspect. It 

 terminates by blunted cone-shaped musculo-tendinous fibres in a large depression situated 

 below the inner tuberosity of humerus. There was no scapular attachment as mentioned 

 by Owen in the birds which he dissected. 



Serratus magims is a thin muscular band imperfectly developed. It arises, apparently, 

 from the 3rd, 4th, and 5th vertebral ribs, about midway between the sternum and the 

 vertebrae. It is inserted into the lower third (or a little more) of the ventral border of 

 scapula, and also into the inferior angle. 



The supraspinatus is represented by a small muscular fasciculus. 



I did not notice in either of the two specimens the small muscular slip, called by Owen 



