THE PENGUINS 289 



sweepiii.s' up the coasts of Chili and Peru, reduces the temperature 

 of the ocean at the Galapagos to 62° or 66° F., whereas its normal 

 temperature at the Equator is 81° to 88° F. 



There is vet one more point of interest in connection with 

 penguins. "What part has natural selection played in their 

 development? Their feathers, their wings, and the backward 

 position of the legs are obviously adaptations for an oceanic life, 

 and the fatty subcutaneous layer is an adaptation for keeping 

 the body warm. All these are due to natural selection. 



But it cannot be said with certainty that all the generic 

 characters are adaptations. The differences here are chiefly 

 in the bill and the tail. In Aptenodytes, the bill is lo^g and 

 slender and is curved downwards at the tip. This seems to be an 

 adaptation for catching fish ; lint it has not been stated that the 

 king penguin feeds more on fishes than other species do. The 

 chief character of Cutarrliactes is the strong bill, which is swollen 

 at the base of the latericorn; and, as the males have larger bills 

 than the females, it may be supposed that this is an adaptation 

 for fighting, and it may be due to natural selection. But it is 

 hard to suggest a use for the feathers on the bill of the PygosceUs, 

 or for the longitudinal grooves at the base of the mandibles in 

 Sphe niscus. In Eudyptula, Spheniscus, Megadyptes, and 

 Aptenodytes, the tail is short, and is composed of from sixteen to 

 twenty feathers ; in PygosceUs and CatarrJiactes, it is long, and is 

 composed of from twelve to sixteen feathers. Of what use can 

 these differences be? Penguins may, perhaps, use their tails as 

 rudders, but it is difficult to say which of these different tails 

 would answer the purpose best. It must be remembered that 

 different genera of penguins sometimes inhabit the same island, 

 as at Kerguelen, the Falklands, and Macciuarie Islands. They 

 seem to have the same food, and the same methods of capturing 

 it. Genera which inhabit similar localities when breeding, and 

 which feed together, so far as is known, on the same kind of food, 

 could not have been differentiated by the direct action of external 

 conditions, and yet it is equally hard to explain how this could 

 have been brought about by natural selection. 



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