EMPEROR PENGUIN. 
The first adult livery is not quite so rich in colour as it becomes after 
another moult, but is in other respects similar. 
The tail-feathers, twenty in number, become worn to mere quills, and often 
in the breeding rookery one may find all the tail-feathers detached from the 
bird and lying embedded in a large lump of hard and dirty ice upon the floe. 
The scales on the feet also will be no longer a rich black, but brown. 
If one compares the measurements of the birds in these various stages 
of growth, one finds that great changes arc effected in the bill; the chief altera¬ 
tion takes place by the lengthening of the upper mandible, the curve of which 
gradually increases. With this growth proceeding at a faster rate along the 
culmen than the tomia, the nostrils, which arc very definite and well marked 
in the first few months of life, gradually become obscured. So also the thicken¬ 
ing, which is apparent on the culmen about one-fourth of its length from the tip, 
is also gradually obliterated by the elongation of the upper mandible. This 
thickening has served in place of an egg scale, which is not developed as a 
deciduous element at all. The angle of the gonys, too, which is quite apparent 
in the lower mandible up to the fifth month, gradually disappears with the 
lengthening of the bill, and eventually the strong uniform curve of the adult 
bill developes to its full extent. Thus 
Nostril to Tip of Bill. 
5 months old 
18 „ „ 
20 „ 
30 „ and onwards 
3 - 5 cm. 
4 - 3 „ 
4-5 „ 
Gape to Tip. 
8T cm. 
9-3 „ 
10-5 „ 
11*8 „ 
The adult measurements of the wings are reached much earlier, even 
within the first six months, as also are the measurements of the feet and 
claws, presumably as a result of the necessity for extra strength and efficiency 
in those parts to avoid natural enemies over and above their uses in obtaining 
food, while the bill lacks this stimulus to rapid growth. 
The individual variation to be found in a series of Emperor Penguins 
amounts to very little indeed. 
The colour of the side plate of the lower mandible is variable, from yellow 
through orange and red to lilac ; but it seems to depend to a certain extent 
on the condition of the peripheral circulation, turning to a livid lilac when the 
circulation is depressed by cold. The depth of the lemon-yellow colour of 
the breast and abdominal feathers varies considerably according to the extent 
to which the summer sun has faded it. When freshly moulted the whole of the 
lower parts must be described as pale lemon-yellow, not white. 
In describing the immature bird also, there is a point worth noting in the 
colour of the crown, which is of pale bluish-grey, marked off as a distinct patch 
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