_Description._--Above greenish grey, finely crossed by narrow fulvous vermiculations; head and neck uniform rusty red: beneath greyish fulvous; breast flammulated with white; flanks and under wing-coverts black with white cross bars: whole length 18·0 inches, wing 10·5, tail 4·0. _Hab._ Paraguay and N. Argentina. Graf v. Berlepsch has recently shown that the Tiger-Bittern of Paraguay differs from _Tigrisoma brasiliense_ (which it generally resembles in plumage) in having the base of the lower mandible partly feathered as in _T. fasciatum_. It is probable that the Argentine Tiger-Bittern belongs to the same form, but we have not yet met with adult specimens of it. It occurs in the northern provinces of the Republic, and was obtained by White in Corrientes, and by Durnford in Salta. 323. NYCTICORAX OBSCURUS, Bp. (DARK NIGHT-HERON.) +Nycticorax obscurus+, _Scl. et Salv. Nomencl._ p. 126; _Durnford, Ibis_, 1878, p. 03 (Buenos Ayres), et p. 399 (Patagonia); _Gibson, Ibis_, 1880, p. 158 (Buenos Ayres). +Ardea gardeni+, _Burm. La-Plata Reise_, ii. p. 508 (Paraná). +Nycticorax gardeni+, _White, P. Z. S._ 1882, p. 624 (Buenos Ayres and Salta); _Barrows, Auk_, 1884, p. 271 (Entrerios). _Description._--Above cinereous; front white; head, nape, and scapulars greenish black; elongated nuchal plumes white: beneath paler, whitish on throat and middle of belly; bill black; feet flesh-colour: whole length 26·0 inches, wing 12·0, tail 4·8, tarsus 3·2. _Female_ similar. _Hab._ Southern half of South America. In the Argentine Republic the Night-Heron lives in communities, and passes the hours of daylight perched inactive on large trees or in marshes on the rushes, and when disturbed by day they rise up with heavy flappings and a loud _qua-qua_ cry. At sunset they quit their retreat, to ascend a stream or seek some distant feeding-ground, and travel with a slow flight, bird succeeding bird at long intervals, and uttering their far-sounding, hoarse, barking night-cry. Where the flock lives amongst the rushes, in places where there are no trees, the birds, by breaking down the rushes across each other, construct false nests or platforms to perch on. These platforms are placed close together, usually where the rushes are thickest, and serve the birds for an entire winter. The breeding-habits of the Night-Heron have already been described in the account of the _Ardea egretta_. In the Falkland Islands, where Captain Abbott discovered a heronry (_cf._ Ibis, 1861, p. 157), their breeding-habits are the same as on the pampas. Fam. XXXVI. CICONIIDÆ, or STORKS.