NORTHERN THREE-TOED WOODPECKER. 
429 
tricate cases, these obscurities are dissipated by a close inspec- 
tion and unprejudiced observation of nature, and we feel much 
gratification in being enabled to unveil to ornithologists the 
mystery of these diversities of plumage in this species, by 
merely pointing out the sexual differences, as well as those 
originating in the gradual change from youth to maturity in 
both sexes ; which, when understood, will not be found more 
extraordinary than in other species. 
The adult female has never been recognised by any author, 
nor, hitherto, even by ourselves, having been misled by others 
in taking the young for her ; and this we have only discovered 
by inspecting a great many specimens. She is precisely similar 
to the male, even in the minutest particulars, excepting the 
absence of yellow on the head, this part being of a rich and 
glossy black. 
The young of both sexes are of a dull blackish ; the seta- 
ceous feathers of the nostrils are greyish, somewhat tinged 
with rusty ; all the feathers of the crown are tipped with white, 
constituting thick dots on that part, to which they give a sil- 
very appearance ; the cheek bands are obscure and much nar- 
rower ; the cervix is more or less varied with white, and the 
feathers of the back being banded with white, gives to that 
part a waved appearance ; the under parts are more thickly 
waved with black : six, instead of four, of the middle tail-fea- 
thers, are almost wholly black, the outer of the six having only 
two or three whitish spots on the outer web. The remaining 
parts, with due allowance, are similar to the adult. 
The young male gradually assumes the yellow, which is at 
first but little extended, and of a pale lemon colour, through 
which are yet for some time seen the white dots attributed to 
the female. She indeed has them very conspicuous in youth, 
as they are not confounded with any yellow, but loses them 
entirely as she advances to the adult state. 
