MTSCULAll SYSTEM. l(7 



ribs, spreading like a thin aponeurosis over the peritoneum 

 covering the abdominal surface of the lungs, as in many of 

 the cold-blooded vertebrata. The iliacus is here a small 

 muscle within the pelvis, and the psoas appears to be want- 

 ing, but the glutei muscles are of great strength, having to 

 support the whole weight of the trunk upon the posterior 

 extremities alone, as in the human body. The tail is moved, 

 and its feathers are expanded, by several lateral muscles 

 both above and below the coccygeal vertebrae, extending 

 from the sacrum to the spinous, and to the transverse pro- 

 cesses, and extending to the bases of the large quill-feathers 

 themselves. The anterior extremities, like the posterior, 

 have the proximate muscles of great magnitude and strength, 

 while the more distant muscles of these parts are compara- 

 tively small and feeble, and those are especially strong which 

 are placed on the fore part of the sternum, and effect the 

 depression of the humerus, the most powerful and important 

 movement in the flight of birds. The pectoralis major, (Fig. 

 76. d,)' covers nearly the whole surface of the sternum and 

 its crest, and continues its origin along the edge of the cla- 

 vicle, and the surface of the broad ligament which unites the 

 clavicle to the upper margin of the sternum. The insertion 

 of this muscle is extended along a great portion of the hu- 

 meruSj and its magnitude corresponds most generally with 

 the power of flight, and the rapaceous character of the spe- 

 cies. The subclavius, the serrati, the subscapularis, and 

 most of the muscles connected with the scapula, on the 

 upper part of the shoulder, are small in birds as in reptiles, 

 and correspond with the limited extent of surface of that 

 bone. Beneath the extended pectoralis major are the long 

 narrow pectoralis minor, and the coraco-brachialis, which, 

 from its position, looks like a third pectoral muscle. The 

 integuments on the fore part of the wing are expanded like a 

 web, in the bent position of the arms, by two long elastic 

 tendons which originate from a strong cutaneous muscle like a 

 deltoid, extending from the scapula over the head of the hume- 

 rus, (Fig. 76 d, e.) One of these tendons is short, and ex- 

 tends only to a small distance beyond the lower end of the 

 humerus, while the other extends to the wrist, as seen in the 

 annexed figure of the wingof the common buzzard,/a/coteo, 

 (Fig.77. e,e,e.*} In this back view of the muscles of the arm in a 



