1. =Strix.= No ear-tufts; bill light-colored; eyes black; tarsus nearly twice as long as middle toe; toes scantily haired. Size medium. Ear-conch nearly as long as the height of the skull, with an anterior operculum for only a portion of its length; symmetrical. =B.= Inner toe decidedly or much shorter than the middle; inner edge of middle claw not pectinated. First quill shorter than the third; one to six outer quills with their inner webs emarginated. Tail rounded. Feathers of the posterior face of the tarsus not recurved but pointed downwards. I. Nostril open, oval, situated in the anterior edge of the cere, which is not inflated. _a._ Cere, on top, equal to, or exceeding, the chord of the culmen; much arched. Ear-conch nearly as long as the height of the skull, with the operculum extending its full length; asymmetrical. 2. =Otus.= One or two outer quills with their inner webs emarginated. With or without ear-tufts. Bill blackish; iris yellow. Size medium. Ear-tufts well developed; only one quill emarginated … _Otus._ Ear-tufts rudimentary; two quills emarginated … _Brachyotus._ _b._ Cere, on top, less than the chord of the culmen; gradually ascending basally, or level (not arched). Ear-conch nearly the height of the skull, with the operculum extending only a part of its full length, or wanting entirely. † Anterior edge of the ear-conch with an operculum; the two ears asymmetrical. 3. =Syrnium.= Five to six outer quills with their inner webs emarginated. Top of cere more than half the culmen. Without ear-tufts. Bill yellow; iris yellow or black. Size medium or large. Six quills emarginated; toes densely feathered, the terminal scutellæ concealed; iris yellow. Size very large … _Scotiaptex._ Five quills emarginated; toes scantly feathered, the terminal scutellæ exposed; iris black. Size medium … _Syrnium._ 4. =Nyctale.= Two outer quills with inner webs emarginated. Top of cere less than half the culmen, level. Without ear-tufts. Bill yellow or blackish; iris yellow. Size small. †† Anterior edge of the ear-conch without an operculum. The two ears symmetrical. Tail slightly rounded, only about half as long as the wing.