_Description._--Similar to _A. correndera_, but with a smaller bill, shorter and more curved hind claw, less spotted under surface, and different marking of the second outer rectrix, which has a clear and distinct white line along the inner side of the shaft: total length 6·0 inches, wing 3·2, tail 2·4. _Hab._ Peru, Bolivia, and Argentina. One of the Pipits procured at Conchitas belongs to this species, if distinct from the former. I think I recollect it as a resident on the pampas, closely resembling the Cachila in flight and language, but much shyer, and usually found concealed under Tulu grass on dry grounds. Fam. VI. MNIOTILTIDÆ, or WOOD-SINGERS. The Mniotiltidæ, or Wood-singers, are a well-known and very characteristic family of the New World, where they occupy the position of our Sylviidæ. They number some 130 or 140 species, distributed all over America down to La Plata, but most abundant in the southern portions of North America, where the favourite and beautiful genus _Dendrœca_, with about 100 species, plays an important part. In Argentina only four species have as yet been met with. 17. PARULA PITIAYUMI (Vieill.). (PITIAYUMI WOOD-SINGER.) +Parula pitiayumi+, _Scl. et Salv. Nomencl._ p. 8; _Durnford, Ibis_, 1876, p. 158, 1877, p. 168 (Buenos Ayres); _Salv. Ibis_, 1880, p. 352 (Tucuman); _White, P. Z. S._ 1882, p. 594 (Catamarca, Misiones); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 87 (Concepcion, Entrerios); _Sharpe, Cat. B._ x. p. 259, pl. xi. fig. 1. +Sylvicola venusta+, _Burm. La-Plata Reise_, ii. p. 473 (Paraná, Tucuman). _Description._--Above clear blue; mantle and upper back olive-yellow; central tail-feathers blue, all the others, also the quills, blackish; cheeks and under surface of body bright yellow; lower abdomen and under tail-coverts white; upper mandible black, lower yellow; eye brown: total length 4·0 inches, wing 2·05, tail 1·55. _Female_ similar, but much paler in colour. _Hab._ South America. This is a southern representative of a small group of Wood-warblers, which is extensively diffused in the New World. The upper plumage of this small bird is mostly cerulean-blue, the breast and belly yellow. Its Guarani name, according to Azara, is "_Pitiayume_," which means little yellow-breast. I have never heard it sing or utter any note beyond a very feeble chirp as it hops about through the foliage in quest of small caterpillars. Its migration extends south to Buenos Ayres, where it is seen in woods and thickets in pairs or singly; but it is a rare bird, and I have been unable to find out anything about its nesting-habits. 18. GEOTHLYPIS VELATA (Vieill.). (VEILED WOOD-SINGER.) +Geothlypis velata+, _Scl. et Salv. Nomencl._ p. 9; _White, P. Z. S._ 1882, p. 594 (Salta); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 87 (Concepcion, Entrerios); _Sharpe, Cat. B._ x. p. 363, pl. ix. fig. 5.