All the upper surface rufous; the basal portion of the coronal feathers yellow; tail uniform light brown, the external margin of the outer feathers lighter; wings brown, the external margin of the secondaries and the tips of the greater and lesser wing-coverts rufous; throat and all the under surface pale buffy white, each feather having a brown mark down the centre; bill brown; feet black. Habitat, Buenos Ayres, La Plata, (_August_). This bird is about the size of a sparrow. It is nearly allied to _Tyrannula ferruginea_ of Swainson and _M. cinnamonea_ of D’Orbig. and Lafr. 3. MYIOBIUS PARVIROSTRIS. Tyrannula parvirostris, _Gould_, MS. _M. suprà rufobrunneus; pileo, nuchâ humerisque obscurè olivaceo-brunneis; alis brunneis, primariarum et secundariarum marginibus exterius angustè tectricumque latè ferrugineis; caudâ guttureque griseo-brunneis; pectore abdomineque flavescenti brunneis._ Long. tot. 4¹⁰⁄₁₂ _unc._; _alæ_, 2⁶⁄₁₂; _caudæ_, 2²⁄₁₂; _tarsi_, ⁹⁄₁₂; _rost._ ⁶⁄₁₂. Crown of the head, back of the neck, and shoulders, dark olive brown; back and upper tail coverts rufous brown; wings brown; the external edges of the primaries and secondaries finely, and the greater and lesser wing coverts broadly margined with ferruginous; tail uniform greyish brown; throat brownish grey; chest and abdomen sandy brown; upper mandible dark brown; under mandible yellowish brown; feet blackish brown. Habitat, Tierra del Fuego, Chile, and La Plata. This bird inhabits the forests of Tierra del Fuego, and as I procured specimens of it in the beginning of winter (June), it probably remains throughout the year in the extreme southern part of South America. Other specimens were procured on the banks of the Plata, and near Valparaiso in Chile; it has therefore a wide range. 4. MYIOBIUS MAGNIROSTRIS. PLATE VIII. Tyrannula magnirostris. _Gould_, MS. _M. Fæm. Suprà olivaceo-brunnea; caudâ brunnea; rectricum externarum marginibus griseo-brunneis; gutture pectoreque olivaceo griseis; abdomine caudæque tectricibus inferioribus pallidè flavis; alis saturatè brunneis, secundariis tectricibusque late griseo marginatis._ Long tot. 5⁶⁄₁₂; _alæ_, 2⁸⁄₁₂; _caudæ_, 2⁶⁄₁₂; _tarsi_, ¹¹⁄₁₂; _rost._ ⁹⁄₁₂. Crown of the head and back olive brown; tail brown; the external margins of the two outer feathers greyish brown; throat and chest olive grey; abdomen and under tail coverts very pale citron yellow; wings dark brown; secondaries, greater and lesser wing coverts broadly margined with grey; bill and feet black. Habitat, Chatham Island, Galapagos Archipelago, (_October_). This bird and the _Pyrocephalus nanus_, inhabit the same island. Not very uncommon. [Illustration: _Birds. Pl. 8._ _Tyrannula magnirostris._ ]