The nest is made of dry grass on the ground, so cunningly concealed that it is most difficult to find. The eggs are four, white, spotted with reddish brown. When they have young, I have never been able to detect the female flying about in search of food. All through the summer these birds are solitary, but when migrating in the autumn, though many are seen travelling singly, and appear very conspicuous as they fly laboriously in a straight line, at an altitude of about twenty yards from the surface, others are seen making their journey in small flocks or parties composed of six to a dozen individuals. These are the males. The females travel separately, in twos or threes or singly, flying nearer to the earth, with frequent pauses, when the wings cease beating, and intervals of gliding, also darting occasionally to one side, as if the bird had suddenly taken fright. 101. AMBLYRHAMPHUS HOLOSERICEUS (Scop.). (SCARLET-HEADED MARSH-BIRD.) +Amblyrhamphus holosericeus+, _Hudson, P. Z. S._ 1870, p. 114 (Buenos Ayres); _Scl. et Salv. Nomencl._ p. 37; _Durnford, Ibis_, 1877, p. 174 (Buenos Ayres); _Gibson, Ibis_, 1880, p. 18 (Buenos Ayres); _White, P. Z. S._ 1882, p. 602 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 135 (Entrerios); _Scl. Cat. B._ xi. p. 351. +Amblyrhamphus ruber+, _Burm. La-Plata Reise_, ii. p. 491 (Entrerios, Santa Fé, Paraná). _Description._--Black; whole head and neck all round, and upper breast and thighs scarlet; bill and feet black: total length 9·5 inches, wing 4·5, tail 4·0. _Female_ similar. _Young_ uniform black. _Hab._ Paraguay, Uruguay, and Argentina. Azara named this species _Tordo negro cabeza roxa_; it is also called _Boyero_ (ox-herd) by country people, from its note resembling the long whistle of a drover; and sometimes _Chisel-bill_, from the peculiar conformation of the beak, which is long, straight, and has a broad fine point like a chisel. In both sexes the plumage of the head and neck is scarlet, of an exceedingly brilliant tint, all other parts intense black. These birds are lively, active, and sociable, going in flocks of from half-a-dozen to thirty individuals; they remain all the year, and inhabit the marshes, from which they seldom wander very far, but seek their insect food in the soft decaying rushes. They are common on the swampy shores of the Plata, and when seen at a distance, perched in their usual manner on the summits of the tall rushes, their flame-coloured heads shine with a strange glory above the sere sombre vegetation of the marshes. The long whistling note above mentioned is their only song, but it varies considerably, and often sounds as mellow and sweet as the whistle of the European Blackbird.