Whether it is a fine singer or not within the tropics I am unable to say, its vocal powers having received no attention from the naturalists who have observed it. With us in the temperate climate of Buenos Ayres, where it commences to sing in September, it has the finest song of any bird I know, excepting only _Mimus triurus_. Like the English Song-Thrush, but unlike its near neighbours the Red-bellied Thrush and the Magellanic Thrush, it perches on the summit of a tree to sing. Its song is, however, utterly unlike that of the English bird, which is so fragmentary, and, as Mr. Barrows describes it, made up of "vocal attitudes and poses." The two birds differ also in voice as much as in manner. The strains of the Dusky Thrush are poured forth in a continuous stream, with all the hurry and freedom of the Sky-Lark's song; but though so rapidly uttered, every note is distinct and clear, and the voice singularly sweet and far-reaching. At intervals in the song there recurs a two-syllabled note twice repeated, unlike in sound any other bird-music I have heard, for it is purely metallic, and its joyous bell-like "_te-ling te-ling_" always comes like a delightful surprise to the listener, being in strange contrast with the prevailing tone. The song is altogether a very fine one, its peculiar charm being that it seems to combine two opposite qualities of bird-music, plaintiveness and joyousness, in some indefinable manner. I have never heard this species sing in a cage or anywhere near a human habitation; and it is probably owing to its recluse habits that its excellent song has not been hitherto noticed. Azara perhaps mistook the song of this species for that of _Turdus rufiventris_, a very inferior vocalist. The nest is made in the centre of a thick bush or tree six or eight feet above the ground, and is a deep elaborate structure, plastered inside with mud, and lined with soft dry grass. The eggs are four in number, oblong; the ground-colour light blue, abundantly marked with reddish-brown spots. This Thrush has, I believe, a partial migration in Buenos Ayres. In the autumn and winter I have frequently observed it in localities where it is never seen in summer. 2. TURDUS RUFIVENTRIS, Vieill. (RED-BELLIED THRUSH.) +Turdus rufiventris+, _Scl. et Salv. Nomencl._ p. 2; _Burm. La-Plata Reise_, ii. p. 474; _Hudson, P. Z. S._ 1870, p. 89 (Buenos Ayres); _Durnford, Ibis_, 1877, p. 167, 1880, p. 417 (Buenos Ayres); _White, P. Z. S._ 1882, p. 592 (Salta); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 85 (Concepcion). +Turdus rufiventer+, _Seebohm, Cat. B._ v. p. 222. _Description._--Entire upper parts olive-grey; throat white, striped with dark brown, the striped portion extending to the chest; rest of under surface, also under wing-coverts, rufous-red, deepest on the belly; bill brownish yellow; feet brown: total length 9·0 inches, wing 4·6, tail 3·6. _Female_ similar.