The nest is an ingenious structure of dry grasses, fastened to the upright stems of an aquatic plant, three or four feet above the water. The eggs are four, in size and form like those of the English Song-Thrush, spotted somewhat sparsely with black on a light blue ground. The young birds are entirely black at first, and afterwards assume on the head and neck a pale terra-cotta red, which gradually deepens to vivid scarlet. 102. PSEUDOLEISTES VIRESCENS (Vieill.). (YELLOW-BREASTED MARSH-BIRD.) +Pseudoleistes virescens+, _Hudson, P. Z. S._ 1870, p. 549, et 1874, p. 156 (Buenos Ayres); _Scl. et Salv. Nomencl._ p. 37; _Durnford, Ibis_, 1877, p. 175, et 1878, p. 59 (Buenos Ayres); _Gibson, Ibis_, 1880, p. 31 (Buenos Ayres); _White, P. Z. S._ 1882, p. 602 (Buenos Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 135 (Entrerios); _Scl. Cat. B._ xi. p. 352. +Leistes anticus+, _Burm. La-Plata Reise_, ii. p. 491 (Paraná). _Description._--Above and below dark olive-brown; lesser upper wing-coverts, under wing-coverts, and middle of the abdomen yellow; bill black; feet dark brown: total length 9·5 inches, wing 4·6, tail 3·8. _Female_ similar. _Hab._ S. Brazil, Paraguay, Uruguay, and Argentina. In both sexes in this species the plumage is deep olivaceous brown, the breast pure yellow. It is active, strong on the wing, sociable and noisy; and being moreover a pretty and elegant bird, very common in settled districts, and with a preference for man's neighbourhood, it is familiar to every one, and has won amongst many competitors the vernacular name of _Pecho-amarillo_ (Yellow-breast), for with us yellow-breasted species are somewhat numerous. It remains all the year, invariably going about in flocks of from twenty to thirty birds, and feeds on the ground in the fields or on the open plain. While they are feeding, one bird takes up a position on a stalk or thistle-top to keep guard; when he flies down another bird takes his place; if a person approaches, the sentinel gives the alarm, and all the birds fly off in a very close flock, making the air resound with their loud ringing notes. After feeding, they repair to the trees, where they join their robust voices in a spirited concert, without any set form of melody such as other song-birds possess, but all together, flinging out their notes at random, as if mad with joy. In this delightful hubbub there are some soft silvery sounds. Where they are never persecuted they have little fear of man, but they invariably greet his approach with a loud vigorous remonstrance.