The eggs of this species vary somewhat in regard to the distribution and number of the reddish-brown markings with which their white ground is more or less sprinkled. In some they are chiefly gathered in a ring about the larger end; in others they are distributed over the entire egg. Their eggs are smaller and a little less spherical in shape than those of the _septentrionalis_, averaging .58 by .47 of an inch. Parus atricapillus, var. septentrionalis, HARRIS. LONG-TAILED CHICKADEE. _Parus septentrionalis_, HARRIS, Pr. A. N. Sc. II, 1845, 300.—CASSIN, Illust. I, 1853, 17, 80, pl. xiv.—BAIRD, Birds N. Am. 1858, 389; Review, 79.—SCLATER, Catal. 1861, 14, no. 82. _Parus septentrionalis_, var. _albescens_, BAIRD, Birds N. Am. 1858, xxxvii. _? Parus atricapillus_, PR. MAX. Cab. Jour. VI, 1858, 119. SP. CHAR. Length about 5.50 inches; wing, 2.70; tail about 3 inches. Head above and below black, separated by white on the sides of the head; back brownish-ash. Beneath white, tinged with pale brownish-white on the sides. Outer tail-feathers, primaries, and secondaries broadly edged with white, involving nearly the whole outer web of outer tail-feather. Tail much graduated; the outer feather about .50 of an inch shorter than the middle. Second quill about as long as the secondaries. HAB. Region of Missouri River to Rocky Mountains. This race is very similar to the _P. atricapillus_, but differs from it somewhat as _atricapillus_ does from _carolinensis_. Its size is much greater; the tail proportionally longer, and much more graduated; the white of wing and tail purer and more extended. The bill appears to be stouter and more conical. The back has, perhaps, a little more yellowish. The spurious or first primary is larger. It will be a difficult matter to retain this as a species distinct from _atricapillus_, in view of the insensible gradation from one form to the other; and it may be looked upon, with scarcely a doubt, as simply a long-tailed Western variety of the common species. _P. occidentalis_, and, probably, even _P. carolinensis_, may even fall under the same category, their peculiarities of color and size being precisely such as would _a priori_ be expected from their geographical distribution. HABITS. The Long-tailed Titmouse appears to have an extended distribution between the Mississippi Valley and the Rocky Mountains, from Texas into the British Possessions, specimens having been received from Fort Simpson and Lake Winnipeg. Among the notes of the late Robert Kennicott is one dated Lake Winnipeg, June 6, mentioning the dissection of a female of this species found to contain a full-sized egg. A memorandum made by Mr. Ross, dated at Fort William, May 15, speaks of this bird as abundant at Fort Simpson, from August until November, the last having been seen November 10. One was shot, June 2, on Winnipeg River, “a female, who was about to lay her egg.”