Durnford gives us the subjoined account of this species:--"I have not observed this bird to the south of Buenos Ayres, but have constantly seen it from March to July to the north of the city. Unlike _Larus maculipennis_, it never wanders inland, but frequents the shallow shores of the La Plata, feeding on dead fish or offal, and flocking round the fishermen when they are hauling their nets to get a share of the spoil. As a rule, this species does not mix with _Larus maculipennis_, though now and then they are seen together; but all the flocks or parties I have observed when flying from one spot to another have always been composed of birds of its own kind. Adults, after once attaining their pearl-grey hood, never lose it, though in winter it becomes rather lighter, and those with white heads are immature birds, which do not attain their full plumage till after their second moult. I have seen many birds throughout May and June of the present year with well-defined dark grey hoods. Some specimens, when first killed, have a delicate faint pink tinge on their underparts, also observed in _L. maculipennis_, which, however, quickly fades after death. The colour of the iris varies a good deal in different examples, being pale grey, grey with a tinge of yellow, and grey with a tinge of light wood-brown. This is probably attributable to age. The narrow rim of naked skin round the eye is dark coral-red; legs and feet the same, but of a duller shade; beak rather darker than the legs." Order XVII. PYGOPODES. Fam. LI. PODICIPEDIDÆ, or GREBES. The Grebes, although perhaps more especially a development of the Arctic lands, are sparingly represented all through the tropics, and reappear in augmented numbers south of the Antarctic circle. Within the Neotropical Region nine to eleven species are met with, of which five are found inside our limits. Three of these are peculiar Patagonian species, the other two are widely spread over America. 419. ÆCHMOPHORUS MAJOR (Bodd.). (GREAT GREBE.) +Podiceps bicornis+, _Burm. La-Plata Reise_, ii. p. 520 (Rio Paraná). +Æchmophorus major+, _Scl. et Salv. Nomencl._ p. 150; _Durnford, Ibis_, 1877, p. 203 (Buenos Ayres), et 1878, p. 405 (Centr. Patagonia); _Barrows, Auk_, 1884, p. 316 (Entrerios); _White, P. Z. S._ 1883, p. 433 (Buenos Ayres); _Withington, Ibis_, 1888, p. 473 (Lomas de Zamora). +Podiceps chilensis+, _Darwin, Zool. 'Beagle,'_ iii. p. 137 (Buenos Ayres). +Podiceps major+, _Scl. et Salv. Ex. Orn._ p. 190; _Gibson, Ibis_, 1880, p. 164 (Buenos Ayres). _Description._--Above blackish; occipital crest divided, bronzy black; wide bar across the wing white: beneath white; chin dark ashy; neck, breast, and sides of belly (in adult) more or less red; bill yellowish; feet dark: whole length 21·0 inches, wing 8·0, tail 1·5. _Hab._ South America.