This Spine-tail is resident, solitary, and extremely timid and stealthy in its movements, living always on the ground among the long grass and cardoon-thistles. At times its inquisitiveness overcomes its timidity, and the bird then darts up three or four yards into the air, and jerking its tail remains some moments poised aloft with breast towards the intruder, emitting sharp little notes of alarm, after which it darts down again and disappears in the grass. When driven up it has a wild zigzag flight, and after reaching a considerable height in the air darts down again with astonishing swiftness, and comes back to the very spot from which it rose. It is, however, incapable of sustained flight, and after being flushed two or three times refuses to rise again. In spring the male perches on the summit of a cardoon-bush, or other slight elevation, and at regular intervals utters a pleasing and melancholy kind of song or call, which can be heard distinctly at a distance of a thousand yards, composed of four long clear plaintive notes, increasing in strength, and succeeded by a falling trill. When approached it becomes silent, and dropping to the ground conceals itself in the grass. Under a cardoon-bush or tussock of grass it scoops out a slight hollow in the ground, and builds over this a dome of fine dry grass, leaving a small aperture arched like the door of a baker's oven. The bed is lined with dry powdered horse-dung, and the eggs are five, bluntly pointed and of a very pale buff colour. The interior of the nest is so small that when the five young birds are fledged they appear to be packed together very closely, so that it is difficult to conceive how the parent bird passes in and out. The nest is always very cunningly concealed, and I have often spent days searching in a patch of cardoon-bushes where the birds were breeding without being able to find it. 204. SYNALLAXIS MALUROIDES, d'Orb. (WREN-LIKE SPINE-TAIL.) +Synallaxis maluroides+, _Scl. et Salv. Nomencl._ p. 64; _Scl. P. Z. S._ 1874, p. 26; _Durnford, Ibis_, 1877, p. 180, et 1878, p. 61 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 208 (Entrerios). _Description._--Above, front and middle of crown chestnut; hind head, neck, and back pale fulvous brown, thickly marked with longitudinal black shaft-spots; lores white; wings blackish, the feathers edged with pale ochraceous, the basal part of secondaries very pale brown, forming a transverse bar; tail pale chestnut-brown, the two middle feathers with a broad black mark on the inner web; beneath white, breast and flanks washed with pale brown, and freckled with very small dark brown spots; under wing-coverts white; bill and feet pale horn-colour: whole length 6·1 inches, wing 2·0, tail 2·9. _Female_ similar. _Hab._ South Argentina.