Very similar to the preceding, but smaller, and with the bill disproportionately weaker. Very similar, also, to _Falco peregrinus_, but differing from both in the colors of the young bird, and in other characters. Adult. Frontal band of white, very narrow. Head and neck above, and cheeks, clear black, with a tinge of cinereous; other upper parts, bluish cinereous, every feather having transverse bands of brownish black, lighter on the rump and upper tail-coverts. Throat and breast, pale reddish white; other under parts, lighter, with rounded spots and transverse bands of black, and with a tinge of cinereous on the flanks and abdomen. Tail above, pale bluish cinereous, with transverse bars of brownish black, and narrowly tipped with white. Patch of black on the cheek, very large, and scarcely separated from the same colors of the back of the head and neck. Dimensions. Total length, females (of skin) about 17 inches, wing 13 to 13½, tail 6 to 6¾ inches; males, total length 14½, wing 11½ to 12, tail 5½ to 6 inches. Younger. Entire plumage above, dark brown; many feathers, especially on the rump, tipped with rufous; tail above, brown, with a tinge of ashy, and barred with rusty on the inner webs. Under plumage pale reddish ferruginous, paler on the throat, all the feathers with broad longitudinal stripes of black, and many, also, with irregular transverse stripes of the same color, which predominates on the flanks and under wing-coverts, and which are marked with reddish white bars and circular spots. Tibia, with transverse bars of brownish black. Dimensions. Female (of skin), total length about 17 inches, wing 12, tail 6½ inches. Hab. Bear creek, California, (Mr. E. M. Kern.) Coast of Lower California, (Dr. Heermann.) Chili, (Lieut. Gilliss.) Spec. in Mus. Acad. Philada., and Nat. Mus. Washington. Obs. This bird, of which we have seen numerous specimens, appears to be distinct from _Falco anatum_. It is uniformly smaller than either that species or _F. peregrinus_, but resembles Indian or other Asiatic specimens of the latter strongly. The young differ from the young of the species just mentioned, especially in the deeper and different red color of the under parts of the body. In this character they more resemble _Falco peregrinator_ of India, _Falco puniceus_ of Africa, _Falco melanogenys_ of Australia. It has also generally the cheeks as strongly marked with a black patch as the latter, and can, by that character, be distinguished from either _F. anatum_ or _F. peregrinus_. This species appears to inhabit the western portion of America as far south as Chili. 3. Falco polyagrus. Cassin, _new species_. The American Lanier Falcon.