WINGS AND FEET 
sequence they have been able to retain large 
wings for aerial flight. That they can develop 
great speed under water and are very expert 
fish-catchers is well known. 
The other line of evolution, the subaqueous 
flight by anterior propulsion, or by the use of 
the wings alone, reaches its height in the 
penguins, and probably in the extinct great 
auk, two birds widely separated genetically 
but converging to the same result in this par- 
ticular. Both birds in developing speed under 
water by the use of the wings, reduced them 
in size to the proportions of seal’s flippers, — 
most markedly so in the case of the penguins, — 
thereby showing that large wings are not only 
unnecessary, but even a hindrance in suba- 
queous flight. In attaining this end they were 
obliged to sacrifice aerial flight. This the 
penguins were able to do owing to the absence 
of land mammals in their antarctic breeding 
grounds. The same conditions existed for the 
greak auk at its chief breeding place in this 
country on Funk Island, until the arrival of 
that most destructive land mammal, the white 
man. 
The diving petrel of the Straits of Magellan 
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