100 THE MYOLOGY OF THE RAVEN. 



appendage ; and finally by another digitation, the 

 largest of the three, from a like origin on the outer 

 surface of the following rib. These three digitations 

 form a broad, flat muscle lying close against the parietes 

 of the thorax. Its fibres converge and pass upwards and 

 forwards, but as they enter the scapulo-thoracic space 

 they become converted into a broad, thin, flat tendon, 

 which, passing between the two divisions of the sub- 

 scapularis, is inserted on a line, covering the junction 

 of the middle and anterior thirds of the outer margin 

 of the corresponding scapula (Fig. 24). This muscle, 

 when the ribs are fixed, draws down the scapula to the 

 side of the chest, but when the shoulder-girdle is 

 fixed by the opposing set of muscles, it draws up the 

 ribs to which it is attached, and thus increases the 

 capacity of the chest, and performs an important 

 function in the act of inspiration. 



From what I quoted from Sir Richard Owen, above, 

 it would seem that this muscle corresponded with his 

 pectoralis minor, and if we be permitted to compare 

 the two, it seems to correspond even with the pectoralis 

 minor in a man, but a far greater amount of study will 

 have to be undertaken than has been done up to the 

 present time, before we can say much about such 

 homologies. 



Mivart says of the pectoralis minor that " the 

 smaller pectoral is a much less constant muscle than 

 the large one, being very frequently absent. Even in 

 animals closely allied to man (e.g. many Apes) it is in- 

 serted into the capsular ligament of the humerus instead 

 of into the coracoid process. It may form one with the 

 pectoralis major, as in birds" (Elem. Anat., p. 326). 

 It will be seen that this last statement of this authority 

 cannot be reconciled with what we have found to be the 



