304 3fusdes of the Chelo7iian Shoulder-girdle. 



If our homologizing of the Cheloniaii shoulder-girdle be correct, 

 the representative of this muscle should arise from between the cora 

 coid and acromion elements. Its insertion should be into the exter- 

 nal or radial tuberosity. Now let us see how nearly these require- 

 ments are met. In the Chelonians there are two, more or less distinct 

 bundles of muscle arising from the acromion and coracoid — from the 

 edges facing each other and from the lower surfaces (PI. 18, figs. 1, 5 

 and 6, 6, 6'', e' ,). In some genera these two bundles are quite distinct 

 and separate throughout all their fleshy portion, and in others they 

 are continuous, forming a broad but thin bundle, filling up the space 

 between the acromion and coracoid, even to their medial extremities — 

 the fibers forming the middle part of the biindle arising from the cor- 

 aco-acromial ligament ; Imt, in all cases observed, the two bundles 

 have a common insertional tendon, which is inserted into the head of 

 the radial (the "greater" in anthropotomy, the "lesser" of Cheloni- 

 ans) tuberosity of the humerus (PI. 13, figs. 3 and 4, e). These two mus- 

 cles are the M. acroinio-humeralis secundas, and the M. coraco-hioite- 

 rcdis secnndus. It will be ol)served that the insertion of their com- 

 mon tendon .is near the insertion of M. scapxdo-acromio-hximeralis, the 

 representative of the " infi*aspinatus " and "teres minor," the relation 

 between them being almost precisely that which is observed in anthro- 

 potomy. 



The only other humeral motor arising from this surface of the 

 human scapula is the " coraco brachialis." In man this muscle arises 

 from the extreme end of the coracoid process, together witli one 

 head of the triceps (PI. 12, fig. 1, t). In its course it lies outside of 

 the " subscapularis," and is insert;ed into the shaft of the humerus 

 near its middle, in a line with the lesser or ulnar tuberosity (PI. 12, fig. 



3, 7). 



In the Chelonians we find a muscle ai'ising from the upper surface 

 of the coracoid (PI. 13, fig. 2, 7), passing outside of the representa- 

 tive of the '•'• subscapularis^'' and inserted into the humerus on the 

 head and lower edge of the ulnar tuberosity (PI. 13, figs. 3 and 4, 7), 

 which is here greatly developed, so that it is larger than tlie radial 

 one. This is the M. coraco-hunieralis primus, and must be regarded 

 as the representative of the " coraco-brachialis," if the assumptions 

 already made be correct. 



The " biceps " of anthropotomy arises by two heads ; one area of 

 origin covers the rim of the glenoid cavity at the base of the cora- 

 coid (PI. 12, fig. 1, 9); the other area, in connection with that for the 

 "coraco-brachialis," covers tlie end of the coracoid process (9«). Tlie 



