The Purple Martin is occasionally seen in the eastern provinces of La Plata when migrating, but has not been found nesting anywhere so far north as Buenos Ayres. I met with it breeding at Bahia Blanca on the Atlantic coast, and on the Rio Negro, where it is very common. It arrives in Patagonia late in September, and leaves before the middle of February. On the 14th of that month I saw one flock flying north, but it was the last. It breeds in holes under the caves of houses or in walls, and its nest is like that of _P. chalybea_; but many also breed in holes in the steep banks of the Rio Negro. They do not, however, excavate holes for themselves, but take possession of natural crevices and old forsaken burrows of the Burrowing Parrot (_Conurus patachonicus_). In size, flight, manners, and appearance the Purple Martin closely resembles the following species, the only difference being in the dark plumage of the under surface. The language of the two birds is also identical; the loud excited scream when the nest is approached, the various other notes when the birds sweep about in the air, and the agreeably modulated and leisurely-uttered song are all possessed by the two species without the slightest difference in strength or intonation. This circumstance appears very remarkable to me, because, though two species do sometimes possess a few notes alike, the greater part of their language is generally different; also because birds of the same species in different localities vary more in language than in any other particular. This last observation, however, applies more to resident than to migratory species. [3] [I here follow Mr. Sharpe in considering the Purple Martin of Argentina and Patagonia separable from the closely allied northern species of North America. But I am altogether sceptical about its occurrence in Chili, which Dr. Philippi expressly diaries (P. Z. S. 1868 p. 534) and for which I know of no good authority.--P. L. S.] 26. PROGNE CHALYBEA (Gm.). (DOMESTIC MARTIN.) +Progne chalybea+, _Scl. P. Z. S._ 1872, p. 606 (Buenos Ayres); _Scl. et Salv. Nomencl._ p. 14; _White, P. Z. S._ 1882, p. 595 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 88 (Concepcion); _Sharpe, Cat. B._ x. p. 178. +Progne domestica+, _Burm. La-Plata Reise_, ii. p. 477; _Sharpe, Cat. B._ x. p. 177. _Description._--Entire upper parts deep purple-blue; lesser and median wing-coverts the same; wing- and tail-feathers black, glossed with steel-blue; throat, fore neck, and chest ash colour; breast, abdomen, and under tail-coverts pure white; bill and feet black: total length 8 inches, wing 5·7, tail 3·2. _Female_ similar. _Hab._ Central and South America.