Vol. XVII 
1g00 
Dwicut, Moult of Quatls and Grouse. 37 
and the black, white or brown chin area, as the case may be, 
-while in females the renewal is still more restricted or even 
suppressed. In the Grouse, I can find little satisfactory evidence 
of prenuptial moult beyond the growth of a few feathers about 
the chin, except in Zagofus, which has the most extensive renewal 
of any of the Quails or the Grouse. It is extremely easy to over- 
look an incomplete and restricted prenuptial moult, for all mem- 
bers of the family being game-birds, they are protected by law 
during most of the year and very few specimens taken at or just 
after this period of moult have found their way into collections. 
There is, however, unquestionable evidence, that this moult takes 
place in several species during April and May, and probably it 
is characteristic of all of them. 
Lagopus alone is peculiar in having an extra or supplementary 
postnuptial moult. The conditions of life under which this Arctic 
bird lives perhaps necessitates this extra moult, which is not, 
however, confined to this genus but appears to be a regular feature 
in the moult of certain Anatide. It is a true moult involving the 
brown or dusky portion of the plumage already wholly renewed by 
the regular and complete postnuptial. It will be discussed more 
fully later. 
Adults, then, have two periods of moult in most if not all of the 
species, while young birds also have two periods of moult, one 
when they doff the downy plumage in which they leave the egg, 
the Postnatal Moult, the other when they assume winter plumage, 
the Postjuvenal Moult. Ail species of Grouse and Quails at the 
latter moult assume a plumage scarcely distinguishable from that 
of the adult.. This is true in a large measure even of Lagopus 
but here again we find an extra moult supplementary to the post- 
juvenal, and, as in the adult, limited in extent. 
In speaking of moult the idea of periodicity must be borne in 
mind. New growth which occurs at any time when one or more 
feathers are torn out is simply an accident. At every period of 
moult feather growth begins at definite points and spreads system- 
atically from them. This is what always happens at any one of 
the series of moults peculiar to each species. If the moult be 
incomplete, the new growth ceases before it has spread to its 
usual limits, and very often stray feathers in its path are left over 
