Page:The Emu volume 3.djvu/122

 is controlled by age. In the oldest and full-plumaged males the vent patch was much purer in colour, smaller, and less conspicuous than in the younger birds. In the latter the patch encompasses a greater portion of the plumage, and frequently is streaked with a darker colour. Judging from two skins only, the converse (as regards the extent of the patch) appears to exist in Gymnorhina longirostris. In the latter species, however, a narrow tract of chocolate-brown above and contiguous to the vent-patch, and absorbing part of the black plumage, indicates the less matured plumage.

In the adult males in full and mature plumage, the black portions of the latter had a bluish-black sheen, thus making a striking contrast with its snow-white portions. It is, perhaps, stating common knowledge to say that the bills of the adult birds showed a high polish, and the colour gradated from whitish at base to blue at point, and that those of the young birds showed a horn colour, with little polish or without polish. In the adult male, which is before mentioned as having almost attained full plumage, the only interruption to the pure white plumage of the upper surface was a few brownish-coloured feathers between the shoulders. The wings and tail also showed a tone of brown, as also the abdomen, which had in addition white and grey margins to the feathers of its lower portion. The vent-patch was not purely white, but only streaked with that colour.

As the skin upon which Mr. Campbell based his specific description of the female of Gymnorhina dorsalis proved afterwards to be an immature bird, I append the description of an adult female in full plumage:—Colour generally sheeny, deep blue-black, excepting the hind neck, shoulders, and edges of wing, which are uniform snow-white, and also excepting the mantle, the feathers of which are black, with conspicuous and well-defined snow-white margins. The over-all measurements of the adult female are shorter than those of the male. Adopting the measurement formula before given, I found such measurements in two adult females to be as follows:—12¼ × 3¾ and 12¼ × 4. The culmen also was shorter in length, the measurements of that feature of same skins being 2⅛ and 2 inches. The depth of the terminal tail-band was proved to be 1⅞ and 1¾ inches. In five young females the same band measured 2⅛, 2, 2¼, 2¾, and 2½ inches.

In a young male (I do not refer to a fledgling) the head was brownish-black; nuchal band white, succeeded by another band of greyish-white feathers with black centres; feathers of the back brownish-black with white or grey margins; shoulder edges of wing pure white; bill whitish at base, becoming blue at point. Over-all measurements, 12½ × 3⅝; culmen, 1.9; depth of tailband, if inches.

In a very young female, shot in the month of July, the head was brownish-black, without sheen; nuchal band dusky white; feathers of upper mantle greyish, with blackish-brown sections; and of lower mantle brownish, with whitish margins; under