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 Adelie 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-pennse. In many cases, 

 however, these pre-pennse are intermixed with down-feathers, " pre-plumulse," which 

 are later succeeded by adult down-feathers. Only " pre-pennse " appear to occur in the 

 young of the Galli and Anseres, for example. It might have been expected that 

 pre-plumulas 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-pennse and pre-plumulse can be seen in the nestling of the 

 Hoatzin (Opisthocomus cristatus) or in the young of the Accipitres, e.g., Falco 

 tinnunculus. There it will be found that the pre-pennse are insignificant in size, and 

 take but a small share in the covering of the body, while the pre-plumulse are of great 

 size, entirely superseding the pre-pennse. It is not surprising, therefore, to find that 

 in some species, e.g., Phalacrocorax and Colymbus, the pre-pennse have entirely 

 disappeared and pre-plumulse 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-pennse or pre-plumulse 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-peunse 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- 



