_Description._--Above fulvous brown, mottled with black, each feather being marked with a large black spot; on the upper part of the back the feathers are faintly edged with whitish grey; wings blackish, basal halves of feathers pale clear brown, forming a transverse bar, the terminal part of the feathers slightly edged on the outer webs and tips with ochraceous; tail blackish, the outer pair of rectrices and broad tips of the next two pairs on each side very pale brown, the two middle feathers broadly margined on both webs with pale greyish brown; beneath pale ochraceous brown, with a pale sulphur-yellowish gular spot; flanks with a few black marks; under wing-coverts light cinnamon; bill and feet pale horn-colour: whole length 7·8 inches, wing 3·2, tail 3·5. _Female_ similar. _Hab._ Argentina. This Spine-tail, which Sclater has named after me, is the Argentine representative of _S. humicola_ of Chili. It is common on the pampas, and is sometimes called by the gauchos "_Tiru-riru del campo_," on account of its resemblance in the upper plumage and in language to _Anumbius acuticaudatus_, which is named "_Tiru-riru_," in imitation of its call-note. The addition of _del campo_ signifies that it is a bird of the open country. It is, in fact, found exclusively on the grassy pampas, never perching on trees, and in habits is something like a Pipit, usually being taken for one when first seen. It is quite common everywhere on the pampas, and specimens have also been obtained in Cordova, Uruguay, and Patagonia.