The Scissor-tails have one remarkable habit; they are not gregarious, but once every day, just before the sun sets, all the birds living near together rise to the tops of the trees, calling to one another with loud, excited chirps, and then mount upwards like rockets to a great height in the air; then, after whirling about for a few moments, they precipitate themselves downwards with the greatest violence, opening and shutting their tails during their wild zigzag flight, and uttering a succession of sharp, grinding notes. After this curious performance they separate in pairs, and perching on the tree-tops each couple utters together its rattling castanet notes, after which the company breaks up. Fam. XIV. PIPRIDÆ, or MANIKINS. The brilliantly coloured _Pipridæ_ or _Manikins_ are nearly altogether confined to the tropical portions of the Neotropical Region, where they number about 70 species. Only one of these has as yet been discovered intruding in the northern outskirts of the Argentine Republic. 172. CHIROXIPHIA CAUDATA (Shaw). (LONG-TAILED MANIKIN.) +Chiroxiphia caudata+, _Scl. et Salv. Nomencl._ p. 55; _White, P. Z. S._ 1882, p. 608 (Misiones). _Description._--Above blue; cap scarlet; sides of head, nape, and wings black; tail black edged with bluish, two middle rectrices lengthened; beneath blue; throat, crissum, and under wing-coverts black; bill and feet reddish: whole length 6·0 inches, wing 3·1, tail 2·5. _Female_ green, cap scarlet. _Hab._ S.E. Brazil, Paraguay, and N.E. Argentina. White obtained two or three males and one female of this Manikin in the forests of Misiones, on the banks of the Uruguay. One of his specimens is now in the British Museum. Fam. XV. COTINGIDÆ, or COTINGAS. The _Cotingidæ_ are another characteristic Neotropical family, mostly of splendid plumage, and nearly altogether confined within the limits of the tropics. Two stragglers only, belonging to the more obscure sections of the group, are as yet known to occur within the confines of Argentina, though it is quite probable that others may be found later on, when the northern forests are more completely explored. 173. PACHYRHAMPHUS POLYCHROPTERUS (Vieill.). (WHITE-WINGED BÉCARD.) +Pachyrhamphus polychropterus+, _Scl. et Salv. Nomencl._ p. 56; _Durnford, Ibis_, 1878, p. 61 (Buenos Ayres). _Description._--Above cinereous, upper back blackish; cap shining black; wings black, margins of coverts and secondaries white; tail black, four outer pairs of rectrices tipped with white; beneath cinereous, paler on the middle of the belly; under wing-coverts pale grey; bill and feet blackish: whole length 6·5 inches, wing 3·0, tail 2·6. _Female_ above dull green, below yellowish; wings margined with rufous. _Hab._ South Brazil, Paraguay, and N.E. Argentina.