INTRODUCTION xxxv 



in the Game-cock, or by several, as in the Peacock- 

 pheasant. But, beside these, a few birds have a simi- 

 lar, and equally powerful, armature in the wings. In 

 some, as on the "Screamers" (Palamedea and 

 Chauna) , two spurs are developed, one at each end of 

 the fused metacarpal bones — the bones which form 

 the "palm" of the hand ; in all other birds but one spur 

 is developed, and this may spring from one of the 

 wrist-bones, as in the Spur-winged Goose, or from 

 the base of the thumb, as in the Jacanas. 



Flight and its Mechanism. — While, in the posses- 

 sion of feathers, birds are unique in the animal king- 

 dom, they are not to be so distinguished in the matter 

 of flight, for many creatures even far below them in 

 the scale of life have this most enviable form of loco- 

 motion; while the Bats, which belong to man's own 

 class — the Mammalia — on the other side of the scale, 

 are also adepts in the art. In the manner of their 

 flight, at any rate, the birds are peculiar. 



In the study of "the way of the bird in the air," it 

 is difiicult to know where to begin, and having made 

 a beginning, it is by no means easy to tell a plain, 

 straightforward tale. Though birds are essentially 

 flying animals, and though to attain this power they 

 have become profoundly modified as to their bodily 

 shape, they have yet, in some respects, not gone so 

 far as, say, the Bats. The latter have almost com- 

 pletely sacrificed the power of walking, while birds 

 have, with some few exceptions, preserved this. Let 

 us come to closer terms with our subject by a study 

 of the bony framework of the body in its relation to 

 flight. 



