140 HOMOLOGIES OF CERTAIN MUSCLES OF THE SHOULDE-JOINT. 



playing over the lower and outer angle of the coracoid ; it arises also from the 

 three anterior sternal ribs, and from a triangular space on the sternum, lying 

 between the two other points of origin. It is inserted into the great tuberosity 

 of the humerus by a tendon attached distally and internally to those of the 

 epicoraco-humeral and deltoid. 

 eh. Epicoraco-humeral muscle. It arises from the mesial point of the sternum or 

 'rostrum' of the bone, from the coraco -clavicular membrane extending from the 

 sternal rostrum up to the clavicle, and, thirdly, from an irregularly quadrangular 

 praeglenoid headland, which, as verified in a young specimen, is constituted by 

 scapula as well as by coracoid. It is inserted into the humerus a little proximally 

 and internally to the deltoid, and superficially to the coraco-brachialis. It is 

 obviously the homologue of the pectoralis secundus s. levator humeri of ordinary 

 birds. (See Meckel on Anatomy of Cassowary, 'Meckel's Archiv,' 1830, 



P- 255- 50 



be. Tendon of biceps inserted into the humeral, and not, as in the Crocodile, into 

 the cephalic edge of the coracoid. Between this tendon and that of the epicoraco- 

 humeral or pectoralis secundus is seen the coraco-brachialis muscle, much reduced 

 in size as compared with its homologue in. the Crocodile. It has lost all the 

 portion which arose mesially to the insertion of the biceps, and which Meckel 

 called ' coraco-brachialis inferior s. pectoralis tertius,' and Schoepss, 1. c, • pectoralis 

 medius.' Neither Schoepss nor Meckel seems (as far as the name 'deltoides 

 inferior' can show, which they have given to the small muscle arising in ordinary 

 birds from the lip of the coracoid underneath the tendon of the biceps, and 

 inserted into the upper part of the great pectoral tuberosity) to have recognised 

 its homology with the upper part of the coraco-brachialis muscle of the Crocodile 

 and the coraco-brachialis brevis s. rotator humeri (Wood) of mammals. The only 

 difference, however, between the muscle which Meckel and Schoepss call ' del- 

 toides inferior ' in the common Fowl and that which I have called in the Emu 

 'coraco-brachialis' is, that the larger biceps of the former animal has overlaid 

 and stunted the muscle which the smaller biceps of the Emu has allowed to 

 retain its reptilian proportions superiorly to its own insertion. 



d. Deltoid, overlying and concealing from view a teres minor not found ordinarily 

 in birds. 



tc Triceps. 



