620 BTJLLETIN 50, UNITED STATES NATIONAL MUSEUM. 



cc. Cranium not distinctly, if at all, aBymmetrical (if gfiymmetrical abnormal on 

 right side only); external ear-openings reniform, of unequal size, conspicu- 

 ously as3rmmetrical, largest on right side; dermal flap greatly developed 

 on anterior side, also largest on right side; sixth to eighth "■ primaries 

 longest; from four to five outer primaries with inner webs emarginated; tail 

 more than two-thirds as long as wing, strongly rounded; size large (wing 

 300-460 mm.). 

 d. Cranium slightly asymmetrical; vertical axis of right and left external ear- 

 openings equal and greater than longitudinal axis of eye; interramal 

 pteryla fused with mandibular pteryla from gape backward; eyes rela- 

 tively small; face relatively very broad and flat; feet relatively small, 

 with feathering of toes very long, partially concealing claws. 

 e. Squamosal strongly asymmetrical; tenth (apparent outermost) primary 

 longer than third; * four outer primaries with inner web emarginated, 



Scotiaptex (p. 634). 

 ee. Squamosal very slightly asymmetrical; tenth (apparent outermost) pri- 

 mary equal to first; " five outer primaries with inner web emarginated. 



Ulula (extraUmital).^ 

 dd. Cranium symmetrical; vertical axis of external ear-opening greater on left 

 side than on right, and less than horizontal axis of eye, that on right side 

 greater than the latter; interramal pteryla tapering gently backward; 

 eyes relatively large; face relatively less broad and flattened; feet rela- 

 tively larger, with feathering of toes short, not reaching to base of claws 

 (sometimes confined to basal outer part of middle toe only). Strix (p. 639). 

 65. Head with more or less conspicuous ear-like feather tufts; ear-orifice in middle 

 or upper portion of external ear-opening, above the transverse ligamentous 

 "bridge " or else between two transverse ligaments. « (External ear-openings 

 extremely large and conspicuously asymmetrical, but cranium symmetrical), 

 e. Tail not more than half as long as wing, the latter more than seven times as long 



as tarsus Asio (p. 652). 



cc. Tail more than half as long as wing, the latter less than six times as long as 

 tarsus. 

 d. Nostril small, circular; bill and feet relatively large and stout, the toes 

 densely feathered; two outer primaries with inner webs emarginated; lai^er 



(wing 278-305 mm.) Ehinoptynx (p. 670). 



dd. Nostril larger, oval, obliquely horizontal; " bill and feet relatively small and 

 weak,/ the toes completely naked; three outer primaries with inner webs 



emarginated Psendoscops (p. 674). 



00. External ear-opening relatively small, its vertical axis much less than half the 

 greatest height of skull, not crossed by a ligamentous "bridge," nor with margin 

 developed into a dermal flap. 



a Counting from innermost primary; second to fourth from outside. 



i> Eighth from outside. 



" Tenth from outside. 



i Ulula Cuvier, Rfegne Anim., i, 1817, 329. (Type, Strix uralensis 'P3llaa.)—Ptynx 

 Blyth, in Cuvier's Animal Kingdom, 1840, 175, footnote. (Type, Strix uralensis 

 Pallas.) (Palaearctic Begion; monotypic?) 



« The details of structure of the external ear-openings, which can not be exactly de- 

 termined from dried skins, are assumed to be the same in Rhinoptynx and Pseudoscops 

 as in Asio. 



1 In these characters agreeing with Ask>, which sometimes also has the toes naked. 



