NORTHERN TIIREE-TOED WOODPECKER. 265 



in young birds. There is a circumstance however that could not be 

 explained by supposing a difference of age, for while some .specimens 

 are seen with no appearance of white or yellow on the crown, but having 

 that part as well as the body, rich shining black, others with a good 

 deal of lemon yellow on that part, are of a duller black, much varied 

 with white. As in other doubtful and intricate cases, these obscurities 

 are dissipated by a close inspection 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 origi- 

 nating 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 setaceous feathers 

 of the nostrils are grayish, 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 silvery appearance; the cheek-bands are obscure 

 and much narrower ; 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-feathers 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 iirst but 

 little extended, and of a pale lemon color, 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 adi-.lt state. 



