54 EDWARD A. WILSON. 



prove conclusively that the Adelie Penguin takes fourteen months to assume its adult 

 plumage, and two years to reach maturity. The one immature bird that we captured 

 in McMurdo Sound in February was of the glossy blue-backed, white-throated phase, 

 which had but a month ago shed its down. The other was considerably larger, with 

 still a white throat, but a dark brown plumage, which was on the point of being 

 shed, by an autumnal moult, and which during the month of February would be replaced 

 by the full black-throated, blue-black plumage of the adult. Having undergone these 

 changes it would join the nesting colonies in the following spring, and at the com- 

 mencement of its own third year begin to breed. 



This brown plumage is merely the weathered condition of the first year's suit, in 

 which some of the blue colour remains, but from which the black has faded by the 

 weathering of a winter and of a summer's sun. The bleaching power of the Antarctic 

 sun is quite extraordinary, and the Adelie Penguin is not the only bird that suffers 

 from it. The adult Adelie is also changed from bluish black to brown before it moults, 

 as also is the Emperor Penguin, both adult and immature. The skua gull's dark 

 brown feathers are often bleached pure white, and the same effect was seen not only in 

 the hair of all the seals, but even in ourselves, for hair and beards were in several 

 cases bleached to a flaxen whiteness at the end of some months of sledging on the 

 Barrier snow plains. That the brown Adelie Penguins taken in February were on the 

 point of moulting was obvious from the fact that just beneath the skin the new set of 

 feathers was imbedded in a mass of fat. The adults were also at this time moulting, 

 and the whole process would be over for young and old well before the onset of 

 the actual winter. 



There is nothing to add to what has already been done in describing the adult 

 bird, though of its variations a word or two may be said. In the ' Southern Cross ' 

 collections a bird was mentioned by Dr. Sharpe which had a patch of white feathers 

 on the nape. As individual variation in any species was held to be a question of the 

 greatest interest, we kept a constant look-out for examples to illustrate it both in this 

 and every other animal we came across, the interest lying mainly in the fact that the 

 number of species being very limited there is no keen competition and no great 

 difference in the conditions of life or difficulty in obtaining food. And, so far as the 

 Adelie Penguins were concerned, we were struck more by the extraordinary uniformity 

 of their plumage than by the number of even trifling variations. 



We procured but one bird irregularly marked, somewhat as in the example men- 

 tioned by Dr. Sharpe in the ' Southern Cross ' collections, and we saw from the ship 

 at times, when it was impossible to procure the specimens, about two or three other 

 examples of variation in the distribution of black and white about the head and neck. 

 That there should be some such tendency might be expected from the fact that it 

 changes so markedly in the second year ; but it is interesting also for the bearing it has 

 on the utility of the markings of just that region of the body. 



These examples, though few, are important as far as they go because they 



