BIKDS OP NORTH AND MIDDLE AMEKICA. 685 



i. Coloration lees brownish above; penciling of under parts heavier 

 but more sparse. (Eastern Colorado to Durango.) 



Otus asio aikeni (p. 695). 

 a. Coloration more brownish above; penciling of under parts finer 



and denser. (California.) Otus aslo bendirei (p. 701). 



hh. Wing averaging more than 168 in male, more than 174 in female. 

 i. Wing averaging less than 170 in males, less than 176 in females. 

 j. Darker than 0. a. bendirei. (Western Oregon.) 



Otus asio brewsteri (p. 700). 

 jj. Much the palest of all forms, with much white. (Eastern Colo- 

 rado to eastern Montana.) Otus asio maxwelliae (p. 696). 



ii. Wing averaging more than 176 in males, more than 179 in females. 



j. Grayer and slightly larger (wing averaging 177.8 in male, 186.3 



in female); not dichromatic (no brown phase). (Western 



Montana to northeastern California, eastern Oregon, eastern 



Washington, and southeastern British Columbia.) 



Otus asio macfarlauei (p. 697). 

 jj. Browner and slightly smaller (wing averaging 176.5 in male, 

 179.2 in female); dichromatic (a tawny-brown phase). 

 (Northwestern Washington to southern Alaska, near coast.) 



Otus asio kennicottli (p. 698). 



gg. Smaller (wing averaging less than 155 in male, less than 157 in female) ; 



vermiculations finer and denser, both above and below. 



h. Larger (wing averaging 152.6 in male, 156.5 in female); toes more 



densely feathered. (Southwestern New Mexico to southeastern 



CaUfomia and northern Sonora.). . .Otus asio cineraceus (p. 702). 



hh. Smaller (wing averaging 144.9 in male, 149.7 in female); toes more 



scantily feathered. (Southern Lower California.) 



Otus asio xantusi (p. 703). 

 ee. Middle toe, measiu-ed from angle between middle and outer toes, not 

 more than 14 mm.; bristly tips to feathers of face greatly developed; 

 occiput and lower hindneck with pale buffy spots, forming two more or 

 less distinct broken bands, interruptii^ general color of upper parts; 

 black streaks on upper and under parts relatively much broader. 



(Southern Arizona to Guatemala.) Otus trichopsis (p. 704). 



dd. Outer webs of exterior scapulars mostly pale buffy, broken distally by 

 dusky vermiculation or mottling; pale grayish buff spots on proximal 

 half of longer primaries decidedly narrower than darker interspaces; legs 

 finely mottled or vermiculated. (State of Chihuabua, northwestern 



Mexico.) Otus vinaceus (p. 708). 



cc. Basal portion of toes scantily bristled, the feathering on lower portion of tarsus 

 ending abruptly. (Costa Eica to southern Mexico.). .Otus cooperi (p. 710). 

 66. Toes wholly and absolutely naked. 

 c. Outermost primary shorter than secondaries; tail nearly if not quite half as 

 long as wing, usually more than half as long; ear-tufts well developed; iris 

 yellow. 

 d. Toes alone, or together with only extreme lower part of tarsus, naked; smaller 

 (wing averaging less than 193). 

 e. Tail more than half as long as wing; tarsus feathered to base of toes or else 

 (0. harbarus) size very small (wing 129 in male, 135.9-144 in female), and 

 fine bristly tips to feathers of face greatly developed. 

 /. Tarsus densely feathered to base of toes; bristly tips to feathers of face 

 slightly or moderately developed; wing averaging at least 142 in male, 

 at least 151 in female. 



