This bird is not very common. It frequents damp ground, where rushes grow, on the borders of lakes. It feeds on the ground and _walks_. It is certainly allied in many respects with the foregoing species, but in its power of walking, and in feeding on the ground, there is a marked difference in habits. As it has lately been described (Swainson’s Nat. Libr. Ornith. x. p. 106.) as the female of the _L. perspicillatus_, I will here point out some of its chief distinguishing characters. Its beak is slightly more depressed, but with the ridge rather more plainly pronounced. In the _L. perspicillatus_, the upper mandible is entirely yellow, excepting the apex; in the _L. erythropterus_, it is entirely pale brown, excepting the base. The eye-lid in the former is bright primrose yellow, in the latter blackish yellow. The tail of _L. erythropterus_ is squarer and contains only ten feathers instead of twelve: the wing is ⁴⁄₁₀ of an inch shorter, and the secondaries relatively to the primaries are also shorter. The red colour on the primaries represents, but does not correspond with, the white on the black feathers of _L. perspicillatus_; and the secondaries in the two birds are quite differently marked. In _L. erythropterus_, the third, fourth, and fifth primaries are the longest, and are equal to each other; the second is only a little shorter than the third. In _L. perspicillatus_ the third is rather shorter than the fourth and fifth; and the second is proportionally shorter relatively to the third, so that the outer part of the wing in this species is more pointed than in _L. erythropterus_. The hinder claw in the latter is only in an extremely small degree straighter than in the former; and this, considering that the _L. perspicillatus_ is generally perched, and when on the ground, can only hop; and that the _L. erythropterus_ feeds there entirely, and walks, is very remarkable. [Illustration: _Birds. Pl. 9._ _Lichenops erythropterus._ ] [Illustration: _Birds. Pl. 10._ _Fluvicola Azaræ._ ] 1. FLUVICOLA ICTEROPHRYS. _D’Orb. & Lafr._ Mag. de Zool. 1837. p. 59. Muscicapa icterophrys, _Vieill._ Encyc. Meth. p. 832. Le Suiriri noirâtre et jaune, _Azara_, No. 183. Specimens were found by me both at Monte Video and at Maldonado, on the banks of the Plata. I found Coleoptera in their stomachs. 2. FLUVICOLA IRUPERO. _G. R. Gray._ Tyrannus Irupero, _Vieill._ Ency. Meth. p. 856. Muscicapa mœsta, _Licht._ Cat. p. 54. Muscicapa nivea, _Spix_, Av. pl. 29. f. 1. Pepoaza nivea, _D’Orb. & Lafr._ Mag. de Zool. 1837. p. 62. Irupero, _Azara_, No. 204.