The Nacunda breeds in October, and makes no nest, but lays two eggs on a scraped place on the open plain. Mr. Dalgleish says of the eggs:--"They are oval-shaped, and resemble much in appearance those of the Nightjar, except that the markings, which are similar in character to those of the latter, are of a reddish-brown or port-wine colour." After the breeding-season they are sometimes found in flocks of forty or fifty individuals, and will spend months on the same spot, returning to it in equal numbers every year. One summer a flock of about two hundred individuals frequented a meadow near my house, and one day I observed them rise up very early in the evening and begin soaring about like a troop of swallows preparing to migrate. I watched them for upwards of an hour; but they did not scatter as on previous evenings to seek for food, and after a while they began to rise higher and higher, still keeping close together, until they disappeared from sight. Next morning I found that they had gone. In Entrerios, Mr. Barrows tells us, this Goatsucker is an abundant summer resident, arriving early in September, and departing again in April. It is strictly crepuscular or nocturnal, never voluntarily taking wing by daylight. In November it lays a pair of spotted eggs in a hollow scooped in the soil of the open plain. These in shape and markings resemble eggs of the Nighthawk (_Chordeiles virginianus_) somewhat, but are of course much larger, and have a distinct reddish tinge. We found the birds not uncommon near Bahia Blanca, February 17, 1881, but elsewhere on the Pampas we did not observe them. 243. CHORDEILES VIRGINIANUS (Gm.). (WHIP-POOR-WILL.) +Chordeiles virginianus+, _Scl. et Salv. Nomencl._ p. 96; _Barrows, Auk_, 1884, p. 24 (Entrerios); _Berlepsch, J. f. O._ 1887, p. 120 (Paraguay). _Description._--Above black, varied and mottled with brown; wings black, with a broad white bar across the bases of the five outer primaries; tail black, with brown cross bands and a broad white subapical bar: beneath white, with dense blackish cross bands; breast blacker; broad throat-band white; bill black; feet pale brown: whole length 8·5 inches, wing 7·8, tail 4·0. _Female_ similar, but throat-band tawny and no white band on the tail. _Hab._ North and South America. The well-known "Whip-poor-Will" of the U. S. appears to extend its winter-migration into Northern Argentina. Mr. Barrows has recorded the capture of two specimens of this species at Concepcion in Entrerios in January 1880 and December of the same year. Its occurrence in Paraguay is also known to us, and Natterer obtained examples of it in S.E. Brazil. 244. ANTROSTOMUS PARVULUS (Gould). (LITTLE GOATSUCKER.)