12 W. P. PYCRAFT. 
here than outline the facts which showed me the need of some such inquiry as that on 
which we have embarked. 
These three plumages are developed, in anything like completeness, in but a few 
groups. But they can he followed in the owls for example, with one remarkable 
exception. In the Tawny, or Eagle Owl, for instance, it will be found that the nestling 
is at first clothed in long, woolly down ; later, before quitting the nest, this is replaced 
by feathers, having a superficial resemblance to down, but which, when examined, are 
found to be intermediate in character between down feathers on the one hand and 
definitive feathers on the other. Down-like in their softness, they are yet feather-like 
in their colouration, and in that each feather is made up of a main shaft, rami, and radii, 
whereas the down feather is umbelliform. But while the head and trunk are thus 
clothed the quill and tail feathers are those of normal definitive feathers, and functional. 
This plumage is worn till the autumn, when the trunk feathers at least are replaced by 
new, and these of the typical adult structure. The exception referred to is found in the 
nestling barn owls. These birds have the down succeeded immediately by contour 
feathers, indistinguishable from those of the parent. To this we shall refer again 
presently. 
This second generation of feathers we may call provisionally “ mesoptyles.” The 
penguin must certainly be regarded as having preserved what must be looked upon as 
a somewhat, perhaps very, ancient succession of plumages, but in these birds the 
“ mesoptyles ” have degenerated to mere down feathers. The megapodes, as is already 
known, shed their down feathers within the egg and emerge feather-clad. But these 
feathers, as I pointed out some time since (14, 15), differ conspicuously from the 
feathers which follow the next moult. In the light of my recent discovery the true 
interpretation of this plumage is clear—it is a mesoptyle dress. The differences between 
the “ down” feathers of the Galli and Anseres now become capable of interpretation. 
They do not, as I imagined, represent a primitive type of down feathers homologous 
with the woolly, and so presumably degenerate, down of, say, the Alcidz, but answer to 
‘‘mesoptyles.” The protoptyle or first generation of feathers would seem to be 
wanting in these birds, but I had the good fortune to discover small tufts of down 
adhering to the tips of the mesoptyles of a young Chlephagarubidiceps. Thus, then, we 
may assume that this first generation, since it has not yet been traced, has been lost in 
all the Galli, and probably all the Anseres save perhaps this species and one or two 
allied genera. It is significant that the only species in which it has so far turned up 
has a striped nestling plumage, which is undoubtedly a primitive sign. 
Among the Galli, it is to be noted, the mesoptyles present varying degrees of 
perfection, in some, as in Meleagris, for example, a rhachis and aftershaft are fairly well 
developed, while in Tetrao, for example, the mesoptyles have become umbelliform. 
Similarly in the case of the Tinami. In Calodromus, for instance, the main axis is 
large and strong, and the rami set fairly close together, while the radii bear a close 
resemblance to those of the definitive feather. The after shaft is here also as long as the 
