54 EDWARD A. WILSON. 
prove conclusively that the Adélie 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 Adélie Penguin is not the only bird that suffers 
from it. The adult Adélie 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 Adélie 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 
Adélie 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 
