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