686 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



g. Larger and paler (wing averaging 153 or more in male, 157 or more in 

 female). 

 h. Under parts with pencilings of very regular "herring-bone" pat- 

 tern, the mesial black streaks very distinct; upper parts more 

 streaked than spotted; larger (wing averaging 170.9 in male, 172.1 

 in female). (Costa Rica to Paraguay, southern Brazil, etc.). 



Otus choliba (p. 711). 



hh. Under parts with pencilings irregular, with mesial black streaks 



less distinct (or if distinct much less regular), often indistinct or 



obsolete; upper parts more spotted than streaked; smaller (wing 



averaging less than 160 in males, less than 171 in females). 



i. Darker and browner, with general coloration more uniform; face 



brown; larger (wing averaging 170.2 in female). (Vera Cruz, 



southeastern Mexico, to Guatemala.).. Otus guatemalse (p. 715). 



a. Paler and less brownish, with general coloration less uniform; 



face dull whitish; smaller (wing averaging less than l(jO in 



female). {Otus hastatus.) 



j. Less buffy brown above, and more densely vermiculated 



beneath; smaller (wing averaging 153 in male, 157 in female). 



(^Western Mexico.) Otus hastatus hastatus (p. 718). 



jj. More buffy brown above, less densely vermiculated beneath; 

 larger (wing averaging 159.2 in female). (Yucatan.) 



Otus hastatus thompsoni (p. 719). 



gg. Smaller and darker (wing averaging 142 in male, 151 in female). 



(Highlands of Vera Cruz, eastern Mexico.). .Otus cassini (p. 720). 



ff. Tarsus not feathered to base of toes, the extreme lower portion being 



naked; fine bristly tips to feathers of face greatly developed; wing 



129 in male, averaging 142 in female. (Highlands of Guatemala.) 



Otus barbarus (p. 723). 

 ee. Tail less than half as long as wing; lower portion of tarsus naked ; colora- 

 tion more uniform, usually without distinct spots above or below, the 

 vermiculations finer). (Costa Rica to Panama.) 



Otus vermiculatus (p. 724.) 

 (id. Lower third, or more, of tarsus naked; larger (wing averaging 183). (Costa 



Rica and Panama; Colombia?) Otus nudipes (p. 727). 



cc. Outermost primary longer than secondaries; tail much less than half as long 

 as wing; ear-tufts short, almost rudimentary; iris brown. (Highlands of 

 Guatemala north to Idaho and southern British Columbia.) 



Otus flammeolus (p. 728). 

 aa. General color cinnamon-rufous or chestnut-rufous. 

 b. Toes with bristles. 

 c. Bristly tips to feathers of face slightly developed; middle toe (measured from 

 angle between middle and outer toes) not less than 15 mm. (Otus asio.) 

 d. Smaller (wing averaging less than 156 in male, less than 158 in female). 

 e. Darker; wing averaging 144.7 in male, 151.3 in female. 



Otus asio asio (p. 688). 

 ee. Paler; wing averaging 155.2 in male, 157 in female. 



Otus asio mccallii (p. 693). 

 dd. Larger (wing averaging more than 160 in male, more than 165 in female). 

 Otus asio nsevius and Otus asio hasbrouckio (pp. 690, 694). 



a With only one specimen of the rufous phase of 0. a. hashroucld I am not able to 

 state the differences (if any there be) between that and the same phase of 0. a. naevius. 



