Thalassidroma furcata. (Gmelin.) Procellaria furcata. Gm. Syst. Nat. I., p. 561. (1788.) Procellaria orientalis. Pallas. Zoog. Ross. As. II., p. 315. (1831.) Thalassidroma cinerea. Gould. Form. Wing long; second quill longest; tail forked; legs shorter than usual in this genus; under coverts of the tail long. Dimensions. Total length (of skin) about 8 inches; wing 6; tail 4 inches. Colors. Entire plumage light cinereous or lead color; lighter, and in some specimens, nearly white on the abdomen and under tail coverts; lesser wing coverts darker; in some specimens nearly black; quills and tail slightly tinged with brown; greater wing coverts and secondaries pale on their outer edges; primaries nearly white on their inner edges; bill and feet black. Hab. Coasts of Oregon, Russian America, Northeastern Asia, and the Pacific Ocean. Spec. in Nat. Mus., Washington, and Mus. Acad., Philad. This bird belongs to a group of the genus _Thalassidroma_, of which _T. marina_ is the best known species, an inhabitant of the Southern Pacific Ocean, and figured by Mr. Gould as a bird of Australia. All the species of this group are characterised by cinereous plumage, a strong distinctive character from the greater part of the birds of this genus, which are of dark colors, and in some species nearly black. The present bird does not, in any considerable degree, resemble any other American species, and may be easily recognised. SYLVICOLA KIRTLANDII.—Baird. Kirtland’s Warbler. PLATE XLVII. Adult. Of the smaller birds of North America, no group exceeds that of the Warblers, in variety and richness of color. It is, too, one of the largest of the groups of our birds, embracing not less than forty species, besides several which are South American. Migrating in the spring, and again in the autumn, these little birds are known in the Middle and Southern States, for the greater part as visitors only, though various species are residents during the summer, which have been supposed to continue their journey much further north, before undertaking the duties of incubation. The Blackburnian Warbler (_Sylvicola Blackburniæ_), the Chestnut-sided (_S. icterocephala_), the Yellow-backed (_S. Americana_), and several others, breed in the mountains of Pennsylvania. The Prairie (_S. discolor_), the Blue-winged (_Helinaia solitaria_), and two or three other species, are to be met with every summer in the neighborhood of Philadelphia. The greater number of species proceed further north, but much the majority of all known as North American rear their young within the limits of the United States, as well as in more northern countries; but by no means exclusively in the latter, as is to be inferred from the representations of various authors. The Black-poll (_S. striata_), raises its young in the State of Maine.