Inches. Total length 4¾ Wings 4¾ Tail 2 Tarsi ½ Habitat, Monte Video, (_November_). Mr. Gould says, “this species is closely allied both to the common martin, and to the last species; from the former bird, however, its bare legs at once distinguish it, while it differs from the latter in being rather larger in size, in having an obscure white mark on the forehead, at the base of the bill, and in having the metallic lustre of the upper surface deep steel green, instead of purple, which is the prevailing colour of both _Hirundo leucopygia_ and _H. urbica_.” It is abundant on the northern bank of the Plata, and more common than the _H. purpurea_, which frequents the same localities. It probably replaces on the eastern side of the continent, the _H. leucopygia_ of Chile. 3. HIRUNDO CYANOLEUCA. _Vieill._ It is nearly allied to the two latter species, but is readily distinguished from them by the absence of the white rump. I procured specimens in September, both from Valparaiso, and from Bahia Blanca (North Patagonia). At the latter place it built in holes in the same bank of earth with _P. purpurea_. CYPSELUS UNICOLOR. _Jard._ C. unicolor. _Jard. et Selby_, Illust. Ornith. pl. 83. I obtained a specimen of this bird from St. Jago, Cape de Verd Islands. (_September_). It more resembled a swallow than a swift in the manner of its flight. I only saw a few of them. Insects occur so scantily over the bare and parched plains of basaltic lava, which compose the lower parts of the island of St. Jago, that it is surprising how these birds are able to find the means of subsistence. FAMILY.—HALCYONIDÆ. HALCYON ERYTHRORHYNCHA, _Gould_, Proc. Zool. Soc. 1837. Alcedo Senegalensis var. β, _Lath._