_Certhia fusca_, BARTON, Fragments of the Natural History of Pennsylvania, 1799, II. _Certhia familiaris_, VIEILL. Ois. Am. Sept. II, 1807, 70 (not the European bird); also of WILSON and AUDUBON.—MAYNARD, Birds E. Mass. 1870, 93. _Certhia americana_, BONAP. Comp. List. 1838.—REICH. Handb. I, 1853, 265, pl. dcxv, figs. 4102, 4103.—BAIRD, Birds N. Am. 1858, 372; Review, 89.—MAX. Cab. Jour. 1858, 105.—COOPER & SUCKLEY, P. R. R. Rep. XII, II, 1859, 192.—HAMLIN, Pr. Bost. Soc. N. H. 1864—66, 80. _Certhia mexicana_, COOPER, Orn. Cal. 1, 1870, 58. SP. CHAR. Bill about the length of the head. Above dark brown, with a slightly rufous shade, each feather streaked centrally, but not abruptly, with whitish; rump rusty. Beneath almost silky-white; the under tail-coverts with a faint rusty tinge. A white streak over the eye; the ear-coverts streaked with whitish. Tail-feathers brown centrally, the edges paler yellowish-brown. Wings with a transverse bar of pale reddish-white across both webs. Length, 5.50; wing, 2.60; tail, 2.90. (No. 827.) _Young._ (5945, Steilacoom, W. T.; Dr. J. S. Cooper.) Resembling the adult, but streaks above indistinct, and the feathers there tipped indistinctly with blackish; the rufous restricted to the upper tail-coverts. Breast and jugulum with very minute blackish wavings or indistinct bars. HAB. Whole of United States, to Red River Settlement. Specimens from the far west are purer white beneath, much as in _costæ_, but those from the northwest coast have the white tinged with light rusty. Though purer white below, these specimens are much browner above than Eastern ones,—sometimes more so than in _familiaris_, but then there is the yellowish crissum never seen in this “species,” and the proportions are quite different. Thus it will be seen the _C. americana_ may always be distinguished from the other forms; when most resembling _costæ_ in the grayish tints of the upper plumage (as in Eastern examples), the lower parts are less purely white, and the bill and claws smaller; when like it in the proportions and pure white of the lower parts (as in Western specimens), the colors above are altogether more brown. The yellowish crissum of _americanus_ will also distinguish them. Though often resembling _familiaris_ in the colors of the upper parts, the latter may always be distinguished by its ashy lower parts without yellowish crissum, the shorter tail, with its less acute feathers, and stouter bill. _C. mexicanus_ is still more different in colors, for which see that variety.