BLACKCOCK (Lyruruus tetrix), a bird of the family Tetra onidae, or grouse, the female of which is known as the greyhen. In size and plumage the two sexes offer a striking contrast, the male weighing about 41b., its plumage, for the most part, of a rich glossy black, shot with blue and purple, the lateral tail feath ers curved outwards so as to form a fan-like crescent, and the eye brows bright vermilion and destitute of feathers. The female weighs only 21b., its plumage is of a russet brown colour, irregu larly barred with black, and its tail feathers are but slightly forked. The males are polygamous, and, during the spring, as semble on definite display-grounds, where they display and fight fiercely for possession of the females. The nest, composed of a few stalks of grass, is on the ground, and the female lays from six to ten eggs of a dirty yellow colour, speckled with dark brown. She hatches and rears her brood alone. The plumage of both sexes is at first like that of the female. The blackcock is dis tributed over the highland districts of northern and central Europe, and parts of Asia. It is abundant in the Scottish High lands.