An example of this species, now in the British Museum, was procured by White in Catamarca. 167. MYIARCHUS FEROX (Gm.). (FIERCE TYRANT.) +Myiarchus tyrannulus+, _Scl. et Salv. Nomencl._ p. 52; _Durnford, Ibis_, 1878, p. 61 (Buenos Ayres); _White, P. Z. S._ 1882, p. 608 (Salta); _Barrows, Bull. Nutt. Orn. Cl._ vol. viii p. 202 (Entrerios). +Myiarchus ferocior+, _Cab. J. f. O._ 1883, p. 214 (Tucuman). _Description._--Above dark cinereous, more or less olivaceous; wings and tail blackish; wing-coverts and outer secondaries with more or less defined edgings of dirty white; beneath, throat and breast cinereous, abdomen and under wing-coverts sulphur-yellow; bill dark brown; feet blackish: whole length 7·0 inches, wing 3·6, tail 3·4. _Female_ similar. _Hab._ Southern Antilles, and South America down to Argentine Republic. There has been great confusion between this species and _M. tyrannulus_, from which the present bird may be distinguished by the absence of the rufous edgings to the inner webs of the rectrices. Examples of _M. ferox_ are in the British Museum from Punta Lara (_Durnford_), Mendoza (_Weisshaupt_), and Buenos Ayres (_Haslehurst_). 168. MYIARCHUS ATRICEPS, Cab. (BLACK-HEADED TYRANT.) +Myiarchus atriceps+, _Cab. J. f. O._ 1883, p. 215. _Description._--Above greenish olive, cap black; wings and tail blackish, more or less margined with brownish; beneath, throat and neck pale grey; abdomen and under wing-coverts pale sulphur-yellow; inner margins of wing-feathers fulvous; bill dark horn-colour; feet black: whole length 7·0 inches, wing 3·7, tail 3·5. _Female_ similar. _Hab._ N. Argentina, Bolivia, and S. Peru. Schulz found this species as a summer visitor in Tucuman. 169. EMPIDONOMUS AURANTIO-ATRO-CRISTATUS (d'Orb. et Lafr.). (BLACK-AND-YELLOW-CRESTED TYRANT.) +Tyrannus aurantio-atro-cristatus+, _d'Orb. Voy., Ois._ p. 312 (Corrientes); _Scl. et Salv. Nomencl._ p. 53; _Barrows, Bull. Nutt. Orn. Club_, vol. viii. p. 202 (Entrerios). +Tyrannus aurantio-atro-cristatus+, _Burm. La-Plata Reise_, ii. p. 453 (Rio Uruguay, Entrerios, Mendoza). _Description._--Above cinereous; cap shortly crested, black, with a large vertical spot of bright yellow; wings and tail brownish black, wing-coverts and secondaries slightly edged with whitish; beneath as above but rather paler, and with a very slight yellow tinge on the crissum; bill and feet black: whole length 6·5 inches, wing 3·8, tail 3·1. _Female_ similar, but outer primaries less acuminated. _Hab._ Interior of Brazil, Eastern Peru, Bolivia, and Argentina down to Buenos Ayres.