HABITS. Of the history of this variety but little is known. It is found in the southern portion of the Rocky Mountain regions, within the United States, in Arizona and New Mexico. The extent of its area of distribution remains to be ascertained. Dr. Kennerly met with it on Little Colorado River, where he observed it among the scattered bushes along the banks of the river, occurring in large flocks. These passed rapidly from place to place, uttering their short, quick notes. He afterward met with them along the head waters of Bill Williams Fork, inhabiting the tops of the cotton-wood trees. When attracted to them by their notes, they could only be seen after a very careful search. He obtained no knowledge as to their mode of nesting, and no information, so far as we are aware, has been obtained in regard to their eggs. It may, however, be safely conjectured that they are white, and hardly distinguishable from those of the _minimus_. Dr. Coues found them common near Fort Whipple, Arizona. Mr. Ridgway met with this bird in especial abundance among the cañons of West Humboldt Mountains in September. He found it also in all suitable places westward to the very base of the Sierra Nevada Mountains. It was met with principally in the thick brushwood bordering the streams, in ever-restless companies, continually twittering as they flew from bush to bush, in single rows. Mr. Ridgway describes these birds as remarkably active in their movements. If unmolested, they were exceedingly unsuspicious and familiar. During November he found them inhabiting the cedars, always associating in scattered flocks. GENUS AURIPARUS, BAIRD. _Auriparus_, BAIRD, Rev. Am. Birds, 1864, 85. (Type, _Ægithalus flaviceps_, SUND.) GEN. CHAR. Form sylvicoline. Bill conical, nearly straight, and very acute; the commissure very slightly and gently curved. Nostrils concealed by decumbent bristles. Wings long, little rounded; the first quill half the second; third, fourth, and fifth quills nearly equal, and longest. Tail slightly graduated. Lateral toes equal, the anterior united at the extreme base. Hind toe small, about equal to the lateral. Tarsus but little longer than the middle toe. This genus is closely allied to _Paroides_ of Europe, as shown in Birds of North America (p. 399), though sufficiently different. It is much more sylvicoline in appearance than the other American _Paridæ_. Auriparus flaviceps, BAIRD. YELLOW-HEADED BUSH-TITMOUSE; VERDIN. _Ægithalus flaviceps_, SUNDEVALL, Ofversigt af Vet. Ak. Förh. VII, v, 1850, 129. _Psaltria flaviceps_, SCL. P. Z. S. XXIV, March, 1856, 37. _Psaltriparus flaviceps_, SCL. Catal. Am. Birds, 1861, 13, no. 79. _Paroides flaviceps_, BAIRD, Birds N. Am. 1858, 400, pl. liii, fig. 2. _Auriparus flaviceps_, BAIRD, Review, 1864, 85.—COOPER, Birds Cal. 1, 51. _Conirostrum ornatum_, LAWRENCE, Ann. N. Y. Lyc. May, 1851, 113, pl. v, fig. 1 (Texas).