STRUCTURE OF BIRDS. 35 



Plate III. represents the muscular apparatus of the wings, 

 seen after the feathers and skin have been removed. Fig. 1 . 

 shews the bones, which have already been explained. In 

 Fig. 2, which represents the wing seen from above ; and 

 in Fig. 3, representing it seen from beneath, the regions are 

 marked as in the figures of Plate II. ; a, being a portion of the 

 body ; 6, c, the brachium or arm ; ^, c?, the cubitus or fore- 

 arm ; c?, ^, the carpus and metacarpus ; 6, y, the digital bones ; 

 ^, the pollex. The muscles to be described are : 1^^, those 

 inserted into the scapula ; 2dly^ those inserted into the brachial 

 bone ; Mly^ those inserted into the hand. In the figures the 

 same muscles bear the same numbers. 



I. Muscles inserted into the scapula. 



1. The first muscle is the trapezius^ which, arising from the 

 spines of the last cervical and all the dorsal vertebrae, except- 

 ing the last two, is inserted into the dorsal edge of the scapula 

 and the extremity of the furcula. Its action is to draw the 

 scapula towards the spine, and to fix it during flight. 



Under this are the rJiomboideus^ which passes from the spines 

 of some of the anterior dorsal vertebrge, to the dorsal edge of 

 the scapula ; and the levator scapidw^ which, arising from the 

 transverse process of the last cervical vertebra and a few of the 

 anterior ribs, is inserted into the dorsal edge of the scapula, 

 which it pulls upwards and forwards. 



2. The serratus magnus anticus arises by digitations from the 

 last four ribs excepting two, and is inserted into the extremity 

 of the scapula. A slender slip, 2 a, separates from it, to be 

 inserted into the skin of the posterior edge of the brachium. 



There is also a serratus parriis anticus^ or costo-scapularis^ 

 which arises in like manner from the first two ribs, and is 

 inserted into the anterior part of the lower edge of the sca- 

 pula. 



II. Muscles inserted into the humeral or brachial bone. 



3. The two superficial slips seen on the back are analogous 

 to the latissimiis dor si in man. They arise from the spinous 

 processes of the last cervical and some of the anterior dorsal 



