The eggs of this Nuthatch measure .80 by .62 of an inch. Their ground-color is white, but when the egg is fresh it has a beautiful roseate tinge, and generally receives an apparently reddish hue from the very general distribution of the spots and blotches of rusty-brown and purplish with which the eggs are so closely covered. These markings vary greatly in size, from fine dots to well-marked blotches. Their color is usually a reddish-brown; occasionally the markings are largely intermixed with purple. Sitta carolinensis, var. aculeata, CASS. SLENDER-BILLED NUTHATCH. _Sitta aculeata_, CASSIN, Pr. A. N. Sc. VIII, Oct. 1856, 254.—BAIRD, Birds N. Am. 1858, 375, pl. xxxiii, fig. 3; Review, 86.—COOPER, Orn. Cal. 1, 1870, 54. _? Sitta carolinensis_, SCLATER, P. Z. S. 1856, 293 (Cordova); 1858, 300 (Oaxaca); 1859, 363 (Xalapa), 373 (Oaxaca). SP. CHAR. Very similar to _carolinensis_; but upper secondaries with only obscure blackish blotches, instead of sharply defined longitudinal spots of clear black. Bill slenderer and more attenuated. HAB. Western and Middle Provinces of the United States, south to Cordova, Mex. Orizaba (Alpine regions), SUMICH. The characters given above express the essential differences between this and the Eastern race of _S. carolinensis_. In the present form, the depth of the bill opposite its base is .14, the width .17, and .80 or more in length from the forehead; while these same measurements in var. _carolinensis_ are .17, .22, and .70. The obsolete character of the black spots on the secondaries is a persistent feature in the var. _aculeata_. HABITS. This bird chiefly differs from its eastern congener in its more slender bill. There appears to be no difference in regard to their habits, at least none have been noticed, and it is probable there is none other than trivial changes caused by its opportunities of procuring food, and the kinds upon which it subsists. It is supposed to be distributed throughout Western North America, from the British Possessions to Mexico, though Dr. Cooper thinks that it is not a common bird south of San Francisco, and only to be seen there in the colder months. It has been met with at San Diego in February. He did not observe any in the Coast Mountains, near Santa Cruz, but northward they are numerous in the summer, frequenting chiefly the groves of the deciduous oaks, creeping constantly about their trunks and branches in search of insects, which they also occasionally seek on the roofs and walls of houses. Their habits are similar to those of _S. canadensis_, but their movements are said to be slower, and their note is a single harsh call, uttered occasionally, and responded to by their comrades. Dr. Cooper found them quite common in Washington Territory and at Puget Sound. Dr. Suckley also mentions their great abundance.