HAB. United States from the Atlantic to California; not found immediately on the coast of the Pacific? Orizaba (SCL. 1857, 213); Texas (DRESSER, Ibis, 1865, 492); Fort Whipple, Arizona (COUES, P. A. N. S, 1866, 90); Nevada and Utah (RIDGWAY); Mazatlan, Tehuantepec, Cape St. Lucas. The young bird of the year is brown above, brownish-white beneath; the throat immaculate. A maxillary stripe and obscure streaks thickly crowded across the whole breast and sides. There is a faint indication of a paler superciliary stripe. The feathers of the upper parts are all margined with paler. There are also indications of light bands on the wings. These markings are all obscure, but perfectly appreciable, and their existence in adult birds of any species may be considered as embryonic, and showing an inferiority in degree to the species with the under parts perfectly plain. Specimens from the west appear to have a rather longer and narrower bill than those from the east. Summer birds of Cape St. Lucas and the Rio Grande are considerably smaller (var. _obscurus_, Cassin). Length about 6.50; wing, 4.00; tail, 3.00. Some winter skins from the same region are equal in size to the average. Birds of this species breeding south of the Rio Grande, as well as those from Cape St. Lucas, Mazatlan, etc., are very much smaller than those nesting within the United States; but the transition between the extremes of size is so gradual that it is almost impossible to strike an average of characters for two races. The extremes of size in this species are as follows:— _Largest._ (11,271, ♂, Fort Bridger.) Wing, 4.60; tail, 3.35; culmen, .72; tarsus, 1.03. _Smallest._ (17,297, ♂, Mira Flores, L. C.) ” 3.80; ” 2.65; ” .60; ” .84. HABITS. The common Cow Blackbird has a very extended distribution from the Atlantic to California, and from Texas to Canada, and probably to regions still farther north. They have not been traced to the Pacific coast, though abundant on that of the Atlantic. Dr. Cooper thinks that a few winter in the Colorado Valley, and probably also in the San Joaquin Valley.