ANTERIOR LIMBS OF BIRDS, ETC. 67 



cassowary, and others — the wings are alto- 

 gether so undeveloped, that they are iTseless 

 for flight, and the great muscular powers are 

 consequently transferred from the chest to the 

 thighs and haunches. IMany birds use their 

 Avings as weapons, and in the jacana, the 

 horned screamer, and certain species of plover, 

 the shoulders are armed with very sharp, 

 hard, horny spurs, capable of inflicting a 

 severe wound. As among quadrupeds so 

 among birds, we find some which have the 

 anterior limbs transformed into paddles. This 

 is the case with the great auk, {Alca impennis) 

 a large bird inhabiting the arctic seas, and 

 incapable of flight ; nevertheless it uses its 

 wings as oars, with great vigovu- and address, 

 making its way so rapidly that a six-oared 

 boat has been known to give chase in vain. 

 In the antarctic seas, we have various species 

 of penguins, in which the wings, covered 

 with minute scale-like feathers, are even more 

 admirably fashioned as oars. These birds 

 swim submerged, using the wings much in 

 the same Avay as the marine turtle its flippers. 

 On shore the great Patagonian penguins some- 

 times assault each other, striking with the 

 posterior edge of the wing; and IMr. Darwin 



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