CHAPTER III. 



ANTERIOR LIMBS OF BIRDS, KEniLES, AND FISHES. 



In the -wing of the bat we found the bones 

 adapted for the extension of a sensitive mem- 

 brane, the whole constituting an efficient in- 

 strument of flight. In birds, as a general 

 rule, the anterior limbs are also constructed 

 for flight, but in a different manner to what 

 we see in the bat; for the efficiency of the 

 wings depends in birds upon the extent and 

 quality of the feathers of the pinions, which 

 are acted upon by muscles of extraordinary 

 vigour. If we look at the bones of a bird's 

 wing we find them to consist of the upper- 

 arm or humerus, the fore-arm with its two 

 bones, the ulna and the radius ; and a portion 

 analogous to the hand, consisting of wrist- 

 bones (^cai'ims) supporting a thumb, two meta- 

 carpal bones of considerable length, and, lastly, 

 the phalanges in a rudimentary state of two 



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