BUBONID^— THE OWLS. 403 



Family BUBONID^.— The Owls. 



The characters of this family having been given with sufficient 

 detail on page 399, they need not be repeated nor enlarged upon 

 here. The North American genera may be distinguished as follows : 



A. External ear exoessiyely large (extending almost entirely across the head) furnished 

 with an operculum or "flap" along the anterior margin, those of the opposite sides 

 very unUke in form; skull also in some genera very asymmetrical. (Asioninw.) 



a. Size medium to very large (wing 11.50 inches or more). 



1. Asio. Size medium (wing 11.50-13.('0 inches) ; cere large and arched, its length on 

 top exceeding the chord of the culmen; nostrils large, horizontally oval, open- 

 ing laterally; only one to two outer quills with inner webs emarginated; head 

 proportionally small, the ear-tufts variable as to development. 



2. Syrnium. Size medium, or rather large (wing 12 inches or more); cere on top 

 shorter than chord of culmen; nostril comparatively small, nearly circular; four 

 or five outer primaries with inner webs emarginated; head proportionally large, 

 ■with no indication whatever of ear- tufts. Toes partly or entirely naked. Eyes 

 moderately large, black, or dark brown. 



3. Siotiaptex, Size very large (wing 16.00 or more); cere on top longer than chord 

 of culmen, the nostrils as in Syrnium; six outer quills with inner webs emargi- 

 nated; head large, and without trace of ear-tufts. Toes densely clothed with 

 long hair-like feathers. Eyes small, yellow. 



b. Size very small (wing less than S inches). 



4. Nyctala. Cere on top decidedly shorter than chord of culmen; nostrils small, 

 vertically oval, opening in anterior edge of the inflated membrane; two outer 

 quills with inner webs emarginated; head proportionally very large, without 

 distinct ear-tufts. 



B. External ear small, vertically oval, or nearly circular, without operculum, the two of 



opposite sides not dittering in size or contour; skull always symmetrical. f.Babo- 

 ninw.) 

 a. Nostrils opening in the anterior edge of the flat nasal membrane. 



§ Tail even, or very slightly rounded, not more than half as long as the wing. 



5. Megascops, Size small (wing less than 8.00 iuehes). Two to five quills with inner 

 webs emarginated, the second to the fifth longest. Bill weak, light-colored; iris 

 usually yellow (said to be brown in M. fiammeolus). Ear-conch elliptical, about 

 one third the height of the head, with a slightly elevated fringed anterior mar- 

 gin. Ear-tufts usually well developed. 



6. Bubo. Size large (wing 12.00 inches or more). Two or three outer quills with 

 inner webs emarginated, the third or fourth quills longest. Bill robust, black; 

 iris usually yellow (brown in 5. mc^icanus). Ear-conch as in Megascops, hut 

 without the elevated anterior margin, and from one third to one half the height 

 of the skull. Ear-tufts well developed; lower tail-coverts not reaching end of 

 tail; toes covered with short feathers, the claws (and sometimes the terminal 

 scutellfe) wholly exposed; bill not concealed by loral bristles. 



