10 W. P. PYCRAFT. 
grey, deepening to black, or nearly black, on the head. This is succeeded, according to 
Mr. Eagle Clarke, by ‘‘a darker coat of down, to the tips of which the paler down of the 
first coat is attached for a time.” It differs then from the Adélie Penguin only in that 
the down of the first coat is conspicuous on the tips of the second. This is not the case 
in any of the penguins which I examined. In these, consequently, the displaced down 
of the first crop is only to be made out by microscopic examination. But for this it 
would seem that the differences in texture and length between the down of the newly- 
hatched and full-grown chick were simply differences in the rate of growth of a normal 
downy covering. 
The Composition and Sequences of the Neossoptiles. 
I have elsewhere shown that the nestling down of birds may be of two kinds, 
which may exist either singly or in combination. It would seem, so far as our present 
knowledge of the matter goes—which is not far—that as a rule the nestling is clothed 
in down feathers which are finally pushed out on the tips of the first generation of 
contour feathers, and these, in consequence, I have called pre-penne. In many cases, 
however, these pre-pennz are intermixed with down-feathers, “ pre-plumule,” which 
are later succeeded by adult down-feathers. Only “ pre-pennee” appear to occur in the 
young of the Galli and Anseres, for example. It might have been expected that 
pre-plumule also would occur in the Anseres, inasmuch as these birds have a thick under- 
clothing of down feathers when adult, but these do not make their appearance till the 
end of the nestling stage. 
The admixture of pre-penne and pre-plumule can be seen in the nestling of the 
Hoatzin (Opisthocomus cristatus) or in the young of the Accipitres, eg., Falco 
tinnunculus, There it will be found that the pre-penne are insignificant in size, and 
take but a small share in the covering of the body, while the pre-plumule are of great 
size, entirely superseding the pre-penne. It is not surprising, therefore, to find that 
in some species, ¢g., Phalacrocoraz and Colymbus, the pre-penne have entirely 
disappeared and pre-plumulz only remain. So far, the question of the down-plumages 
of nestling birds appears to involve only plain, straightforward issues—the plumage 
may consist of pre-pennze or pre-plumulz only, or a combination of both, then follow the 
teleoptiles. 
As a matter of fact, however, this apparent simplicity is illusive. I have already 
shown that the owls (11) and the megapodes (12) furnish us with exceptions to this 
rule ; inasmuch as in the former the pre-penne are not succeeded by normal contour 
feathers (except in the case of the Barn owl, which has hitherto been supposed to agree 
with all other owls), but by a type of plumage intermediate between down and contour 
feathers ; while the megapodes pass through a downy stage while yet embryonic, and 
emerge with an intermediate type of plumage answering to that of the nestling owl. 
These facts now prove of much more importance than seemed to be the case at the time 
of their discovery. And this because of what has come to light during my investiga- 
