This question leads to another. Why did that giant razor- 

 hill known as the great auk become flightless ? It would seem 

 that its wings somehow failed to keep pace with the growth of 

 its body, so that while they remained sufficient for flight under 

 water, they became useless for flight in the air. Its failure in 

 this led to its extinction, for it was unable to escape from its arch- 

 enemy man. When the old-time sailors, somewhere about one 

 hundred years ago, discovered its haunts in Iceland could be 

 profitably invaded for the purpose of collecting feathers, and bait, 

 they speedily wiped out the race ; for being flightless they were 

 imable to escape the marauders once they had effected a landing. 

 Unhappily there was no Bird Protection Society in those days, 

 to stop this senseless slaughter. 



Here our survey of Birds on the Wing ends. It began with 

 flight through the air, it ends with flight through the water. 

 It is not a little surprising, surely, to find that the same wing 

 can be efficiently used for both these extremes of motion. And 

 still more surprising to find that, this being so, the penguin should 

 have been forced, so to speak, to adopt the expedient of evolving 

 a paddle ; and so forego the power of aerial locomotion. The 

 skeleton of this wing, it was pointed out, differed is no essential 

 from that of the typical avian wing. In some points, however, 

 it has changed conspicuously. For the bones have become greatly 

 flattened, and the several parts of the wing — arm, fore-arm, and 



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