_Hab._ S. America, from Venezuela to Argentina. The Red-fronted Thorn-bird, which is found in the Northern provinces of Argentina, and only occurs as a straggler near Buenos Ayres, resorts to the thickets, and in its habits is said to resemble the _Synallaxes_ of the group to which _S. spixi_ and _S. albescens_ belong. It builds a large nest of sticks, and White says that it makes a peculiar chattering sound that has the effect of exciting other small birds, and causes them to crowd about it. 209. PHACELLODOMUS SIBILATRIX, Scl. (WHISTLING THORN-BIRD.) +Phacellodomus sibilatrix+, _Scl. P. Z. S._ 1879, p. 461; _White, P. Z. S._ 1882, p. 612 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 209 (Entrerios). _Description._--Above dull olive-brown, paler on the sides of the head; front and lesser wing-coverts chestnut-red; wing-feathers blackish, edged with olive-brown; tail light chestnut, the middle pair of feathers and the inner webs of the two next pairs brown, like the back; beneath dirty brownish white, washed with ochraceous on the flanks; under wing-coverts bright cinnamon: whole length 5·3 inches, wing 2·2, tail 2·2. _Hab._ Argentina. This species resembles _P. frontalis_, but differs in its much smaller size, and in having the upper lesser wing-coverts bright rufous. It inhabits the thorny woods of the northern districts of the Argentine country, but I have no reason to regret that I have not personally observed this species, since Mr. Barrows's careful account of its nesting-habits leaves nothing to be desired. He writes:--"An abundant species among the open woods along the Uruguay, and hardly distinguishable at ten paces from half a dozen others. Its nest, however, is unmistakable. The birds begin by fixing a few crooked and thorny twigs among the terminal sprays of some slender branch which juts out horizontally from a tree, or rises obliquely from near its base, and around these twigs as a nucleus more are gathered, until, by the time the nest has reached the proper size, its weight has bent the branch so that its tip points directly to the earth. Nests which are thus begun at a distance of fifteen or twenty feet from the ground are often only two or three feet from it when finished, and a thorough soaking by a heavy rain will sometimes weigh them down until they actually touch. They are more or less oval or cylindrical in shape, and commonly about two feet long by twelve or fifteen inches in diameter, and contain from a peck to a bushel of twigs and thorns. The nest-cavity within is small in proportion to the size of the nest, and occupies its upper part. It is reached by a more or less direct passage-way from below, the external opening being very nearly at the lowest part of the nest, though sometimes a little shelf, or even a pocket, is built on to the side, forming a resting-place in front of the door.