522 



ZOOLOGY. 



While the sternum of the cassowaries and other stnithious 

 birds (Ratitw) is smooth, approaching that of reptiles, that 

 of the higher living birds is keeled or carinate (Fig. 454, 

 crs) ; hence tliese birds are called Cari- 

 natcB ; to this keel and neighboring parts 

 the muscles which raise and lower the wings 

 are attached. 



The fore limbs of birds (Fig. 455) are 

 greatly modified to form the framework of 

 the wings. In spreading and closing the 

 wings, the bones of tlie forearm slide along 

 each other in a peculiar manner. (Coues.) 

 The ulna is usually thicker and longer than 

 the radius, and there are only two carpal 

 bones, one radial, the other ulnar, in adult 

 recent birds. The hand in the Apteryx and 

 cassowaries has but one complete digit, 

 while in other birds there are three digits, 

 which probably correspond to the first, 

 second, and third fingers of the human 

 hand. The wings are attached to a strong shoulder-girdle, 

 which consists of the two collar bones, uniting to form the 

 wish-bone, and of acoracoid bone and scapula. 



Fig. 454. — Stemnm 

 of the Guinea Hen, 

 seen from in front ; 

 crs, crest : c, coracoid 

 bone. — After Gegen- 

 baur. 



Fig. 455.— Right wing hones of a yonng Chicken. A, shoulder : B, elbow ; C, wrist 

 or carpus : Z>,,tip of third finger ; a, humerus ; &, ulna ; c, radios ; d, scapholnnar 

 bone : tf, cuneiform bone ; /, g, epiphyses of metacarpal bones I. k, respectively ; A, 

 metacarpal and its digit £.— From Conea's Key. 



The pelvis of birds is remarkable for the long slender back- 

 wardly projecting ischium and pubic bones; there is generally 



