‘ees Dwicut, Moult of Quails and Grouse. 149 
This extra moult so quickly succeeds the one preceding it that 
new brown and new white feathers may be found almost side by 
side. If, however, we bear in mind how feather growth radiates 
more or less symmetrically from definite points, we can distinguish 
two moults rather than two stages of one, and if we could trace 
the history of each individual feather, we would doubtless find it 
subject to the same laws which govern the development of plumage 
in all species of birds. The difficulty arises of designating the 
intermediate stage of plumage by a name. _ It exactly corre- 
sponds to the ‘autumnal’ or ‘ winter’ plumage of most birds, but 
part of it is soon renewed by the extra moult. It seems to me it 
might best be called the preliminary winter plumage, which, when 
the brown feathers have been replaced, becomes the supplementary 
winter plumage. One thing is evident — the brown or dusky stage 
does not properly belong to the nuptial or summer plumage, for 
its appearance is synchronous with the postnuptial renewal which 
begins among the remiges. Young birds also pass through a pre- 
liminary winter plumage following the juvenal, assuming by the 
postjuvenal moult a dress that is scarcely different from the cor- 
responding stage of adult plumage, although the brown feathers 
acquired are fewer and more scattered. As in the adult, this 
plumage is also followed by a wholly white supplementary winter 
dress. 
The plumages of the Ptarmigans are puzzling not only on 
account of the plumage intermediate between summer and winter 
dress, but also on account of the rapidity with which the moults 
follow each other, one beginning before the previous one is com- 
pleted, and apparently overlapping it at some points. Moreover, 
the incompleteness of the partial moults with the irregular 
retention of feathers peculiar to them adds to the confusion of 
ideas resulting from seeing together an assemblage of feathers 
belonging to several different stages of plumage. As for the 
rapidity with which one moult treads upon the heels of another, 
it can only be said that the mode of life of the Ptarmigans 
requires it and the activity of a feather papilla is no greater than 
the necessity. As a matter of fact, some papilla produce 
approximately one feather in May, another in July and a third 
in September, but there are many which produce but two feathers 
