MUSCULATURE. 271 



scapularis accessorius which is present likewise in the Proechidna. The origin 

 is directly over the center of the glenoid cavity. It passes ental to the triceps 

 back to the lesser tuberosity of the humerus where it inserts just distal to the 

 insertion of the subscapularis. 



The teres major is a large flattened muscle arising from the extreme postero- 

 dorsal angle of the scapula on the external side. It inserts on the humerus 

 by a broad tendon slightly distal to the insertion of the subscapularis. 



The teres minor is lacking in both the Echidna and the Proechidna. The 

 small muscle described as subscapularis accessorius can hardly represent this 

 muscle, on account of its insertion into the lesser instead of the greater tuber- 

 osity. According to Sabatier it is fused with the infraspinatus which seems 

 extremely probable, since the latter is intimately connected along the anterior 

 edge of the scapula, with the S2ipraspinatus where the latter passes out beneath 

 the episternum. 



The coracobrachialis presents quite the same divisions as in the Echidna. 

 The most superficial is the caput longum from the posterior tuberosity of the 

 coracoid by a broad tendon. It passes as a broad muscular band to the internal 

 distal condyle of the humerus where it is inserted by short tendinous fibers. 

 Underneath this head, and from the same origin is the caput breve, which spreads 

 out as a thin muscular sheet over the posterior aspect of the head of the humerus 

 from the lesser tuberosity to the center of the depression between the two 

 tuberosities, and distally for nearly three fourths the length of the humerus. 

 The third portion is much smaller, and is wholly overlaid by the second head. 

 It arises slightly anterior to the latter, in part from the lateral surface of the 

 epicoracoid and passes as a short tenuous sheet to insert on the lesser tuberosity 

 of the humerus just posterior to the insertion of subscapularis. This is the 

 epicoracobrachalis of Coues. 



The biceps arises from the ventral surface of the coracoid below the glenoid 

 cavity. At its anterior edge may l^e separated off a small slip whose origin is 

 from the epicoracoid. The two are closely approximated and after about 

 20 mm. become inseparably fused to form a stout muscle that passes to a tendi- 

 nous insertion nearly a centimeter in length on the medial side of the radius, 

 nearlj' the same distance distal from the sigmoid cavity. The same condition, 

 essentially, is found in the Echidna in which the small sUp from the epicoracoid 

 is considered by Westling a second head. The action of the muscle is to ap- 

 proximate the fore arm to the breast. 



The triceps is very strongly developed, and is separable into the usual 



