Dimensions. _Female_—total length, 22 to 24 inches; wing, 15; tail, 10 inches. _Young male_—total length, 20 inches; wing, 13; tail, 9½ inches. Hab. Southern States; Mexico, abundant; Texas, frequent (Col. McCall); Mississippi, rare (Dr. Jenkins); Peru; Chili (Lieut. Gilliss); Chili, abundant (Gay, Fauna Chilena). Spec. in Mus. Acad., Philada. Obs. Col. McCall, who has seen this bird in large numbers in Texas, represents it as habitually frequenting the ground in the vicinity of water, and especially abundant on both sides of the Rio Grande. It is slow and heavy in flight, and a dull, sluggish bird in all its habits, partaking in these respects of the general characters of the Vultures. The affinities of this species we regard at present as uncertain, and arrange it provisionally only in the present genus and sub-family, but by no means agreeing in our views with late European ornithologists. The foregoing are all the birds of this family which can be regarded as well-established species inhabiting that portion of North America, within our prescribed limits. Respecting their history, one of the most important questions to the naturalist is, the change of plumage from young to mature age, and another change which takes place in assuming their spring or summer and their winter liveries. The latter change is by no means well understood in many species, and to ascertain it completely in any one would yet be an interesting contribution to its history. A few species are known only as of exceedingly rare occurrence in the United States, but the larger number are sufficiently numerous to be investigated without difficulty. Of the former, the Washington Eagle (_Haliaetus Washingtonii_), Harlan’s Buzzard (_Buteo Harlani_), the Black Hawk, the Rough-legged Hawk (_Archibuteo sancti-johannis_ and _lagopus_,) and nearly all the Western species, may be regarded as particularly requiring further research. In the winter season, various species resort to the sea-coast, and others to the margins of bays and rivers in considerable numbers. In the vicinity of the cities these have, however, greatly diminished since the introduction of steamboats and railroads. Steam-engines, and especially locomotives, are innovations for which the Eagles and Hawks evidently have no fancy. To the markets appropriated to the accommodation of farmers and traders from the rural districts in all the cities on the Atlantic seaboard, specimens are frequently brought for sale, a demand, reliable to some extent, having arisen from collectors and amateurs.