There is a striking resemblance to a Thrush in this species, when one sees it running on the ground with its beak somewhat elevated; but when it stands or perches, opening and closing its broad tail with a graceful fan-like motion, the resemblance to the stiff automatic _Turdus_ grows less, and when it flies vanishes altogether--its long wings being as sharply pointed as those of the Peregrine Falcon, while its motions in the air have a Gull-like grace and buoyancy. It is a very pretty bird; the upper plumage is grey tinged with rufous, the throat pure dark grey, breast and belly rufous, wing-coverts light silvery grey, remiges and rectrices dark. Azara classed it under the name of _Pepoaza_ (banded-wing) with the _Tæniopteræ_, to which it comes very near in form, flight, language, and habits, though it has longer legs and runs more on the ground. Its summer home is in Southern Patagonia, but its breeding-habits are not known; in winter it migrates north, and in May is found scattered over the pampas, where it is usually called by the country people 'Chorlo,' a name for all Plovers; for while running swiftly about on the ground, often associating with flocks of Plover, it has a certain resemblance to them. From the hue of its plumage it is also called 'El Chocolate,' a name I have thought it best to preserve. These birds are very sociable, going in small flocks, usually of from half a dozen to twenty individuals; they are restless and active, and quick and graceful in all their movements, and seek their food on the ground, chiefly coleopterous insects, on the great level plains they inhabit. While on the wing they pursue each other playfully in the air, and also attack and chase passing birds of other kinds, apparently in a sportive spirit. Occasionally they perch on a thistle-top or low bush, but never on trees. Their only language is a long, low, plaintive whistle, heard usually on warm still days in winter. 112. TÆNIOPTERA NENGETA (Linn.). (PEPOAZA TYRANT.) +Tænioptera nengeta+, _Burm. La-Plata Reise_, ii. p. 459 (Paraná); _Scl. et Salv. Nomencl._ p. 42; _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 137 (Entrerios); _White, P. Z. S._ 1882, p. 603 (Misiones). _Description._--Above cinereous; lores white; wings black, coverts cinereous; a well-marked speculum at the base of the primaries and the edgings of the outer secondaries white; tail black, tipped with whitish cinereous, basal one-third of tail white; below pale cinereous, middle of throat white, with blackish stripe on each side; middle of belly, flanks, crissum, and under tail-coverts white; bill horn-colour; feet black: whole length 9·0 inches, wing 5·0, tail 3·5. _Female_ similar. _Hab._ S.E. Brazil, Paraguay, Uruguay, Argentine Republic, and Bolivia.