W. p. PYCRAFT : NESTLING BIRDS. 165 



can best be studied in the Tawny Owl. In this bird the 

 first down-phimage is composed of long- delicate plumes, or 

 rather tufts. This stage is succeeded by a quite peculiar 

 plumage, made up of feathers of a semi-plumous type. 

 Unlike the earlier down-feather, but like the typical 

 feather, each of these semi-plumes is found to be composed 

 of a long shaft bearing weak barbs, or rami, and still 

 weaker barbules or radii (Fig. 4). In colour this plumage 

 is faintly barred. The wing and tail quills are now 

 assumed, and in this dress the bird remains until its first 

 autumn, Avhen, by moulting, the typical feathers are 

 developed. 



All the other Owls, I believe, will be found to agree 

 in this matter, save only the Barn-Owls, in which the 

 white, fragile down-tufts are replaced at once by feathers 

 indistinguishable from those of the adult bird (Fig. 3). 

 That this white down is really a degenerate form of the 

 semi-plumous tyj)e seen in the Tawny Owl, the first 

 generation having been suppressed, is, I think, certain. 



In the Gamebirds, and Ducks and Geese, the nestling- 

 down is composed of feathers of the semi-j)lumous type, 

 which I have named, and shall hereafter in these pages 

 call mesoptyles, while I shall use the term protoptyles to 

 designate the down-plumage of the first generation. 



That the nestling-down of the Gamebirds and Geese 

 answers to the ifnesoptyle plumage of the Tawny Owl we 

 may be certain of for two reasons. Firstly because when 

 completely developed, as in the young of the Common 

 Fowl and Turkey, and to a less extent in the Pheasant, 

 such feathers not only have a well-defined shaft, and barbs 

 arranged along it in pairs, but also an aftershaft. This 

 latter, however, is but feebly, if at all, developed in the 

 Geese. Secondly, I have found, in the more primitive 

 Geese, e.</., Gloephacja, distinct remains of the protoptyle 

 plumage adhering to the tips of the mesoptyles. 



The mesoptyle plumage in the Gamebirds, as I have 

 already hinted, does not, in all species, exhibit the same 

 perfection of development, and this fact is of some little 



