In regard to its distinct individual history but little is as yet known. It was discovered and first described by the late Edward Harris, of New Jersey, who accompanied Mr. Audubon in his expedition to the upper branches of the Missouri River, and who obtained this bird on the Yellowstone, about thirty miles above its junction with the Missouri, on the 26th of July. He describes its notes as similar to those of the common _atricapillus_, but less harsh and querulous, and more liquid in their utterance. Subsequently specimens were obtained by Mr. Kern, artist to the exploring expedition under Fremont in 1846. It is the largest species of this genus in America. In its breeding-habits it is not different from the Eastern representatives. Mr. B. F. Goss found this species breeding abundantly at Neosho Falls, in Kansas. They nest in decayed stumps, hollow trees, branches, logs, etc., after the manner of the _atricapillus_. The excavation is usually ten or twelve inches, and even more, in depth. The nest is warmly made of a loose soft felt composed of the fur and fine hair of small quadrupeds, feathers, and the finer mosses. The eggs, usually five, occasionally eight, in number, are of a rounded oval shape, measuring .60 by .50 of an inch. They have a pure dull-white ground, and the entire egg is very uniformly and pretty thickly covered with fine markings and small blotches of red and reddish-brown intermingled with a few dots of purplish. Parus atricapillus, var. occidentalis, BAIRD. WESTERN CHICKADEE. _Parus occidentalis_, BAIRD, Birds N. Am. 1858, 391 (W. Territory); Review, 81.—SCLATER, Catal. 1861, 14, no. 82.—ELLIOT, Illust. 1, pl. viii.—COOPER, Birds Cal. 1, 45. SP. CHAR. Tarsi lengthened. Tail graduated; outer feather about .25 of an inch shorter than the middle. Above dark brownish-ash; head and neck above and below black, separated on the sides by white; beneath light, dirty, rusty yellowish-brown, scarcely whiter along the middle of body. Tail and wings not quite so much edged with whitish as in _P. atricapillus_. Length about 4.75; wing, 2.40; tail, 2.40. HAB. Northwest coast region of the United States. This race is of the same size as _P. atricapillus_, and resembles it in its markings; the ashy of the back is, however, washed with a darker shade of yellowish-brown. The brown of the under parts is so much darker as to cause the predominant color there to be a pale yellowish-brown, instead of brownish-white. The fourth quill is longest; the fifth and sixth a little shorter than the third; the second is about as long as the secondaries. The tail is rounded, rather more so than in most _atricapillus_, the difference in the lengths of the feathers amounting to about .25 of an inch. The amount of light margining to the quills and tail-feathers is much as in _atricapillus_, but rather less, perhaps, on the tail.