Although comparatively nothing is known in reference to the specific habits of this species, they may be very readily inferred from those of the other members of this genus, whose characteristics are all so well marked and so uniform. Dr. Kennerly is the only one of our naturalists who has mentioned meeting the species in its living form. In his Report upon the Birds of Lieutenant Whipple’s Survey he states that he found it in the thick bushes along the Pueblo Creek. Wherever noticed it was constantly in motion, hopping from twig to twig in search of its food. He also found it among the pines of the Aztec Mountains. No mention is made of its nest or eggs, and its nidification remains to be ascertained. GENUS PARUS, LINNÆUS. _Parus_, LINNÆUS, Syst. Nat. 1735. (Type, _P. major_.) GEN. CHAR. Head not crested. Body and head full. Tail moderately long, and slightly rounded. Bill conical, not very stout; the upper and under outlines very gently and slightly convex. Tarsus but little longer than middle toe. Head and neck generally black or brown, with sides white. Nest in holes. Eggs white, sprinkled with red. In the group, as defined above, are embraced several genera of modern systematists. The true black-capped American Titmice belong to the section _Pœcile_ of Kaup, and exhibit but three well-marked forms; one, _P. montanus_, with a white stripe over the eye; one, _atricapillus_, without it, with black head; and one, _hudsonicus_, also without it, and with brown head. The species may be arranged as follows:— 1. _Head and neck, above and beneath, black; their sides white._ A. A broad white stripe above the eye, meeting across forehead. 1. P. montanus. Edges of wing-coverts, secondaries, and tail scarcely paler than general tint above. Beneath ashy-whitish, medially. Wing, 2.85; tail, 2.50; bill (along culmen), .50; tarsus, .69; middle toe, .43; wing-formula, 45, 36, 7, 2; graduation of tail, .18. _Hab._ Mountain regions of Middle and Western United States. B. No white stripe above the eye. _a._ Tail as long as, or longer than, wing. Conspicuous white edgings to wing-coverts, secondaries, and tail-feathers. 2. P. atricapillus. Dorsal region yellowish-cinereous, wings and tail purer ash; sides light ochraceous. White edgings of tail-feathers _not_ margining their ends. Wing, 2.60; tail, 2.60; bill, .40; tarsus, .62; middle toe, .36; wing-formula, 4, 5, 6, 3, 7, 8, 29; graduation of tail, .30. (12,851 ♂: Brooklyn, N. Y.) _Hab._ Eastern Province of North America, north of about 39° … var. _atricapillus_.