Auk 
38 Dwicut, Moult of Quatls and Grouse. Tae 
until another period. There are all dégrees of suppression in the 
extent of the areas involved by a moult which is partial, like the 
prenuptial, and females always renew more limited areas than do 
the males. The postnuptial moult seldom leaves a trace of the 
old plumage, nor as a rule do the complete moults of young birds 
of any species to whatever family they may belong. 
A table that I prepared to show the relations existing between 
plumages and moults among Passerine species is with slight modi- 
fication applicable to the Grouse and Quails. It is as follows: 
Plumages. Moults. 
1. Natal Postnatal 
2. Juvenal Postjuvenal 
3. First Winter First Prenuptial 
4. First Nuptial First Postnuptial 
5. Second Winter (adult) Second Prenuptial (adult) 
6. Second Nuptial (adult) Second Postnuptial (adult) 
ClGe. CEC. ClG., uc. 
This scheme distinguishes a series of plumages followed by 
moults which may be complete, partial, or even suppressed accord- 
ing to species, age, sex and individual. It permits of a plumage 
being called adult whenever evidences of immaturity are lost, and 
it is applicable to the Tetraonide by recognizing, in the exceptional 
case of Zagofus, the supplementary postjuvenal and postnuptial 
moults which produce the white supplementary winter plumage. 
In all the other Grouse and their allies the scheme is without 
exception, save the probability that the prenuptial moult is 
suppressed in some of them. More material must be examined 
to determine this, for as the feathers of these birds suffer compar- 
atively little wear, owing to their structure, it is easy to overlook 
a prenuptial moult limited to a few feathers about the head. 
A better understanding of the development of the different 
plumages at the periods of moult will be gained by taking each 
up in the order in which it appears : — 
1. Watal Down.—'The early history of this first stage of 
plumage must be sought within the egg, but we need only begin 
at the time when the chick emerges from the shell. The young 
of all the Tetraonide are densely covered at this stage with a 
downy plumage. Upon the individual feathers of this down, 
