5. =Scops.= Two to five quills with inner webs emarginated; second to fifth longest. Bill weak, light-colored. Ear-conch elliptical, about one-third the height of the head, with a slightly elevated fringed anterior margin. Size small; ear-tufts usually well developed, sometimes rudimentary. 6. =Bubo.= Two to four outer quills with inner webs emarginated; third to fourth longest. Bill robust, black. Ear-conch elliptical, simple, from one third to one half the height of the skull. Size large. Ear-tufts well developed or rudimentary. Ear-tufts well developed. Two to three outer quills with inner webs emarginated; lower tail-coverts not reaching end of the tail. Toes covered with short feathers, the claws exposed, and bill not concealed by the loral feathers … _Bubo._ Ear-tufts rudimentary. Four outer quills with their inner webs emarginated; lower tail-coverts reaching end of the tail. Toes covered with long feathers, which hide the claws, and bill nearly concealed by the loral feathers … _Nyctea._ ††† Similar to the last, but the tail graduated, nearly equal to the wing. 7. =Surnia.= Four outer quills with inner webs emarginated. Third quill longest. Bill strong, yellow; ear-conch simple, oval, less than the diameter of the eye. Size medium; no ear-tufts. II. Nostril, a small circular opening into the surrounding inflated membrane of the cere. Ear-conch small, simple, oval, or nearly round, without an operculum. First quill shorter than the tenth. 8. =Glaucidium.= Third to fourth quills longest; four emarginated on inner webs. Tarsus about equal to the middle toe, densely feathered. Tail much more than half the wing, rounded. Bill and iris yellow. Size very small. 9. =Micrathene.= Fourth quill longest; four emarginated on inner webs. Tarsus a little longer than middle toe, scantily haired. Tail less than half the wing, even. Bill light (greenish ?); iris yellow. Size very small. First quill longer than sixth. 10. =Speotyto.= Second to fourth quills longest; three emarginated on inner webs. Tarsus more than twice as long as middle toe, closely feathered in front to the toes, naked behind. Tail less than half the wing, slightly rounded. Bill yellowish; iris yellow. Size small.