BAT. 



487 



which have become necessary. The scapulae (s) 

 are large, and of a singular form, and they are kept 

 at a considerable distance asunder by the expanded 

 chest : their coracoid processes are also large, and 

 extend in the direction of the sternum. The clavicles 

 (c) are of enormous size and length, being larger 

 than either the scapula or the sternum, and remark- 

 ably curved in their shape. The sternum is much 

 developed, extending laterally, and having a pro- 

 tecting crest along the middle of its lower surface. 



The humerus (h) is strong, but short; apparently 

 in order to avoid the danger of its being snapped 

 asunder by the violent actions of the pectoral 

 muscles, had it been longer. As the leading object 

 of the structure is to give power to the wing, there 

 was no necessity for the rotatory motion of the 

 bones of the fore-arm ; and accordingly we find 

 them consolidated into one (r) ; or rather no part 

 of the ulna is developed, except the process of the 

 olecranon, or elbow, which has become soldered to 

 the radius. 



These advantages in the construction of the fore 

 extremities are obtained at the expense of the 

 hinder, which are too feeble to support the weight 

 of the body in the upright position required for 



