162 Dwicut, Moult of Quatls and Grouse. Aca 
simply a little further advanced with the lower parts almost 
entirely white and numerous patches of white on the head and 
back, the third primary by its immaturity marking them as young 
birds. 
First Winter Plumage (supplementary), acquired as already 
indicated by a limited supplementary postjuvenal moult which 
removes all dusky retained juvenal and preliminary winter 
feathers. Both sexes become white with black tails and indis- 
tinguishable from J/agopus except in some young males which 
have traces of the black lores peculiar to adults. 
First Nuptial Plumage, acquired by a partial prenuptial moult, 
the extent of which seems to vary with latitude, sex and individual. 
Birds dwelling where snow prevails the whole year acquire but 
few dark feathers, as indicated by a couple of males (L. B. Bishop, 
No. 4182 and No. 4183, White Pass, British Columbia, June 11), 
the latter wholly in worn white winter dress save for a few partly 
grown dusky feathers on the crown, the former with a few on the 
crown and a similar small patch on the throat. It is not possible 
to say how far this moult will extend, but the lateness of the date 
precludes extensive renewal before the postnuptial moult begins. 
Other birds assume a grayish finely vermiculated or mottled dress, 
retaining only the white remiges and their coverts, the black rec- 
trices. the white legs and feet and a variable number of white 
wing-coverts and white feathers of the mid-abdomen. Females 
would seem to undergo a more extensive renewal than males, 
being coarsely mottled and barred with buff and black, and now 
distinguishable for the first time from males by their plumage. 
Second or Adult Winter Plumage (preliminary), acquired by a 
postnuptial moult, probably less complete in higher latitudes. 
The early beginning of this moult is shown by three worn females 
of reinhardi (Amer. Mus. Nos. 64128 and 64129, July 28, and 
No. 67820, July 25, Greenland) which have acquired a few new 
primaries and some dusky body feathers. Males and females 
are practically alike in this preliminary dress, and differ little 
from young birds. 
Second or Adult.Winter Plumage (supplementary), acquired by a 
partial supplementary postnuptial moult, birds becoming wholly 
white with black tails. Males, however, assume jet black lores 
