_Description._--Above pale earthy brown; crown black, striped with clear brown; lores, sides of head, and throat white, with minute black spots; wings blackish, the edges of the outer webs of the primaries and the basal part of the secondaries light rufescent brown; tail black, lateral rectrices tipped and margined with pale grey; beneath pale grey, throat white; bill and feet horn-colour: whole length 6·2 inches, wing 2·4, tail 3·5. _Female_ similar. _Hab._ Chili, Argentina, and Patagonia. This is a restless little bird, seen singly or in parties of three or four. In manner and appearance it resembles the Long-tailed Titmouse (_Parus_), as it diligently searches for small insects in the trees and bushes, frequently hanging head downwards to explore the under surface of a leaf or twig, and while thus engaged continually uttering a little sharp querulous note. They are not migratory, but in winter seem to wander about from place to place a great deal; and in Patagonia, in the cold season, I have frequently seen them uniting in flocks of thirty or forty individuals, and associating with numbers of Spine-tails of other species, chiefly with _Synallaxis sordida_, and all together advancing through the thicket, carefully exploring every bush in their way. D'Orbigny says that it makes a nest of rootlets and moss in a bush; but where I have observed this bird it invariably breeds in a hole in a tree, or in the nest of some other bird, often in the clay structure of the Oven-bird. But in Patagonia, where the Oven-bird is not known, this Spine-tail almost always selects the nest of the _Synallaxis sordida_. It carries in a great deal of soft material--soft grass, wool, and feathers--to reline the cavity, and lays five or six, white, pointed eggs. 190. LEPTASTHENURA FULIGINICEPS (d'Orb. et Lafr.). (BROWN-CRESTED SPINE-TAIL.) +Leptasthenura fuliginiceps+, _Scl. et Salv. Nomencl._ p. 63; _White, P. Z. S._ 1882, p. 611 (Catamarca). +Synallaxis fuliginiceps+, _Burm. La-Plata Reise_, ii. p. 469. _Description._--Above pale earthy brown; forehead and slightly crested crown rufous brown; wings blackish, edges of outer webs of all the wing-feathers and basal part of the secondaries chestnut; tail clear brown; beneath paler, earthy brown; bill and feet horn-colour: whole length 6·0 inches, wing 2·2, tail 3·1. _Hab._ Bolivia and N. Argentina. This species, discovered by d'Orbigny in Bolivia, was met with by White in Catamarca, "on the slopes of the hills, outside the dense wood," and by Prof. Burmeister near Paraná. 191. SYNALLAXIS FRONTALIS, Pelz. (BROWN-FRONTED SPINE-TAIL.) +Synallaxis frontalis+, _Scl. et Salv. Nomencl._ p. 63; _Scl. P. Z. S._ 1874, p. 8; _Salvin, Ibis_, 1880, p. 358 (Salta); _White, P. Z. S._ 1882, p. 611 (Salta, Catamarca). +Synallaxis ruficapilla+, _d'Orb. Voy., Ois._ p. 246 (Corrientes); _Burm. La-Plata Reise_, ii. p. 408 (Paraná).