There are some variations, both of color and proportions, between eastern and western specimens of the Robin. In the latter there is a tendency to a longer tail, though the difference is not marked; and, as a rule, they slightly exceed eastern specimens in size. The broad white tip to the lateral tail-feather—so conspicuous a mark of eastern birds—is scarcely to be found at all in any western ones; and in the latter the black of the head is very sharply defined against the lighter, clearer ash of the back, there hardly ever being a tendency in it to continue backward in the form of central spots to the feathers, as is almost constantly seen in eastern examples; of western specimens, the rufous, too, is appreciably lighter than in eastern. As regards the streaks on the throat, the black or the white may either largely predominate in specimens from one locality. In autumn and winter each rufous feather beneath is bordered by a more or less conspicuous crescent of white; in addition to this, most of the lighter individuals (♀?), at this season, have an ashy suffusion over the breast and flanks; and this, we have observed, is more general and more noticeable in western than in eastern specimens. In fall and winter the color of the bill, too, changes, becoming at this season either partially or wholly dusky, instead of almost entirely yellow, as seen in spring and summer examples. Mexican specimens, found breeding in the Alpine regions as far south as Orizaba and Mirador, most resemble the western series; one, however (No. 38,120 ♂, Orizaba), but in the autumnal plumage, and therefore very possibly a migrant from the North, is hardly distinguishable from No. 32,206, Georgia; it is about identical in proportions, and the rufous is of a castaneous shade, like the deepest colored eastern examples; the white tip to the outer tail-feather is as broad and conspicuous as is ever seen in the latter. HABITS. Scarcely any American bird has a wider range of geographical distribution, or is more numerous wherever found, than this thrush. From Greenland on the extreme northeast to the plateau of Mexico, and from the Atlantic to the Pacific, the Robin is everywhere a very abundant species. Single specimens have been obtained as far south as Coban, Guatemala. Its distribution in the breeding season is hardly less restricted, occurring alike on the shores of the Arctic Seas and on the high lands of Vera Cruz. In the winter months it is most abundant in the Southern States, while in the Middle and even the Northern States, in favorable localities, it may be found throughout the year; its migrations being influenced more by the question of food than of climate. In the valleys among the White Mountains, where snow covers the ground from October to June, and where the cold reaches the freezing-point of mercury, flocks of the Robin remain during the entire winter, attracted by the abundance of berries.