_Young_ (first full, but imperfect plumage: ♂, 24,172, Fort Crook, North California, August 23, 1860; John Feilner). Wings and tail as in the adult (last pale band of latter apparently terminal). Whole head and body with numerous, about equal, transverse bands of dusky and grayish-white; the two colors about equal, but on lower parts both are much wider and more distinct than above the white gradually increasing posteriorly. Breast and outer webs of scapulars with a rusty tinge, the latter scarcely variegated. Eyebrow white, feathers bordered with dusky; eye-circle and ear-coverts bright rusty-rufous; lores much tinged with the same. No facial circle. Wing, 5.50; tail, 2.70. HAB. Guatemala and central Mexico, northward (along Sierra Nevada) to Fort Crook; California (breeding). HABITS. This is essentially a Mexican and Central American species, occurring among the mountains of Mexico and thence to Guatemala. One individual, however, the only one as yet recorded as taken in the United States, was obtained at Fort Crook by Captain John Feilner, and is now in the collection of the Smithsonian Institution. This was a young bird, evidently raised in that locality, and apparently showing that the species breeds in that vicinity. It has been taken also at Orizaba, in the State of Vera Cruz, Mexico. Nothing is known as to any peculiarities of habit. These are not probably different from those of the _asio_. GENUS BUBO, DUM. GEN. CHAR. Size varying from medium to very large; head with or without ear-tufts. Bill black; iris yellow. Two to four outer quills with their inner webs emarginated. Third or fourth quill longest. Bill very robust, the lower mandible nearly truncated and with a deep notch near the end; cere gradually ascending basally (not arched) or nearly straight, not equal to the culmen. Tail short, a little more than half the wing, slightly rounded. Ear-conch small, simple, without operculum; the two ears symmetrical. Subgenera. =Bubo.= Two to three outer quills with their inner webs emarginated. Ear-tufts well developed; loral feathers not hiding the bill, and the claws and terminal scutellæ of the toes exposed. Lower tail-coverts not reaching the end of the tail. (Type, _B. maximus_.) =Nyctea.= Four outer quills with their inner webs emarginated. Ear-tufts rudimentary; loral feathers hiding the bill, and claws and entire toes concealed by long hair-like feathers. Lower tail-coverts reaching to end of the tail. (Type, _N. scandiaca_.) The species of this genus are mostly of very large size, two of them (_B. maximus_ and _N. scandiaca_) being the largest birds of the family. They are nearly cosmopolitan, and are most numerous in the Eastern Hemisphere. SUBGENUS BUBO, DUM. _Bubo_, DUMÉRIL, 1806. (Type, _Strix bubo_, LINN. = _B. maximus_, SIBB.) _Rhinostrix_, KAUP, 1849. (Type, _Strix mexicana_, GMEL. = _B. mexicanus_, RIDGW.) _Rhinoptynx_, KAUP, and _Rhenoptynx_, KAUP, 1857. (Same type.)