_Description._--Head all round, neck, and throat down to upper part of breast black; all the rest of the plumage fine and glossy blue; beak and feet black: total length 15·5 inches, wing 8·15, tail 6·9. _Hab._ S. Brazil, Paraguay, and N. Argentina. This fine species was originally discovered by Azara in Paraguay. In June 1881 specimens were obtained at San Javier, Misiones, by White. He writes: "This bird is found here at times in flocks, and makes a great deal of noise, but is exceedingly wild and difficult to shoot, so that I had to use ball-cartridge to secure this specimen." Suborder II. _OLIGOMYODÆ_. Fam. XIII. TYRANNIDÆ, or TYRANTS. The Tyrannidæ or Tyrant-birds, which play the part of our Flycatchers in the New World, although they are quite different in structure, contribute an important element in the Neotropical Avifauna, numbering as they do more than 350 species. Of these 63 have already been met with within the limits of the Argentine Republic, and the list, will, no doubt, be further extended, as many of these birds are small and dull in colour, and easily hide themselves in the dense forests to which they resort. The pampas are the special home of the Tæniopterinæ, or "Walking Tyrants" as Swainson called them, which have strong feet and long tarsi, and frequent open spaces. Amongst them the genera _Tænioptera_, _Alectrurus_, _Cnipolegus_, and _Lichenops_ may be regarded as specially characteristic of the Argentine avifauna. On the other hand, the Elaineinæ and Platyrhynchinæ, which are eminently birds of the dense forest, are much less numerous within the bounds of Argentina, and are mostly confined to the wooded districts of the north. The typical Tyranninæ form a more mixed group, some species of which, such as _Tyrannus melancholicus_ and _Pyrocephalus rubineus_, are prominent objects in the Argentine ornis. 109. AGRIORNIS STRIATA, Gould. (STRIPED TYRANT.) +Agriornis striatus+, _Burm. La-Plata Reise_, ii. p. 459 (Cordova); _Salvin, Ibis_, 1880, p. 356 (Tucuman); _Döring, Exp. al Rio Negro, Zool._ p. 41 (R. Colorado, R. Negro). _Description._--Above cinereous; wings blackish cinereous with light edgings; tail dark cinereous, with a distinct white margin to the external rectrix, and slight whitish tips to all rectrices; lores blackish; short superciliaries white: below pale cinereous; throat white, broadly striated with black; bill above black, below pale: whole length 9·0 inches, wing 4·5, tail 4·3. _Female_ similar. _Hab._ Eastern Argentina and Patagonia. This species, originally discovered by Darwin in Patagonia, is also found in Eastern Argentina. White obtained it in Catamarca, Durnford in Tucuman, and Burmeister on the Rio Quarto, in Cordova. 110. AGRIORNIS MARITIMA (d'Orb. et Lafr.). (WHITE-TAILED TYRANT.)