+Agriornis maritima+, _Scl. et Salv. Nomencl._ p. 41; _Durnford, Ibis_, 1878, p. 394 (Chupat); _Barrows, Bull. Nutt. Orn. Cl._ vol. viii. p. 137 (Sierra de la Ventana). +Agriornis leucurus+, _Burm. La-Plata Reise_, ii. p. 459 (Mendoza). _Description._--Above cinereous; secondaries edged externally and tipped with white; tail dark cinereous, the four external rectrices with the whole outer webs and about the one-third apical part of the inner webs white, the median rectrices tipped with white; below paler cinereous; throat greyish white, slightly striated with dark cinereous; lower belly, crissum, flanks, and under wing-coverts while, more or less tinged with cinnamomeous; bill and feet black: whole length 9·0 inches, wing 5·3, tail 4·0. _Female_ similar. _Hab._ Argentina, Patagonia, Chili, and Bolivia. This _Agriornis_ was obtained by Durnford at Tombo Point in Central Patagonia, by Burmeister in the Sierra de Uspallata, near Mendoza, and by Barrows in the rocky gorges of the Sierra de la Ventana. Darwin tells us of this species that it "is a scarce, shy, solitary bird, frequenting the valleys in which thickets grow, but often feeding on the ground. In the interior plains of Patagonia, on the banks of the Santa Cruz, I several times saw it chasing beetles on the wing, in a peculiar manner, half hopping and half flying; when thus employed it spreads its tail, and the white feathers in it are displayed in a very conspicuous manner. I also met with the species in the lofty and arid valleys on the eastern side of the Cordillera of Central Chili, and likewise at Copiapo." (Zool. Voy. 'Beagle,' iii. p. 57.) 111. MYIOTHERETES RUFIVENTRIS (Vieill.). (CHOCOLATE TYRANT.) +Myiotheretes rufiventris+, _Scl. et Salv. P. Z. S._ 1868, pp. 138, 141 (Conchitas); _iid. Nomencl._ p. 42; _Durnford, Ibis_, 1877, p. 175 (Buenos Ayres), et 1878, p. 394 (Centr. Patagonia); _White, P. Z. S._ 1882, p. 603 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 140 (Entrerios). +Tænioptera variegata+, _Burm. P. Z. S._ 1868, p. 635 (Buenos Ayres), _Hudson, P. Z. S._ 1870, pp. 333, 545, et 1871, p. 260 (Buenos Ayres). _Description._--Above and below smoky grey, clear on the head and breast; belly, crissum, and under wing-coverts bright rufous; wings black, inner secondaries bright chestnut terminated with white, outer secondaries black, tipped with white; wing-coverts grey, margined with white; tail black, outer margins of external pair of rectrices and tips of all whitish; two outer primaries emarginated; bill and feet black: whole length 9·5 inches, wing 6·7, tail 3·8. _Female_ similar, but outer primaries not emarginated. _Hab._ Patagonia, Argentina, and Paraguay.