FALCONIDvK-TIlE FALCONS. 257 



B. Four outor primaries with tlioir inner webs cut. 



«. Form ligrht, tlie legs .slender; tail of adult without a subterminal band 

 ol' black more distinct than (ho others. 



3. B. zonooerouB. Winir, L">."iO- 17.4(1; tail, 8.50-10.75; culmen 

 .00; tarsus, '.^.50-2.80; mi.ldle toe, 1.G0-1.S5. Entirely deep black,' 

 with more or less concealed pure white spotting. Adiilt. Tail car- 

 bonaeeous-black, with three very broad zones, of pure white on inner 

 web.s and ash on the outer webs. ¥„„„;/. Tail dark brown, the inner 

 webs more or less, sometimes entirely, white, crossed bv nuinerou.s 

 ol)li(iuc bands of black. //(,/,. Mexico (ehiefly western?) and adjacent 

 southwestern portions of the United States (Arizona, Coi-ks; Southern 

 California, San Diego, Cooi'kh). 



4. B. lineatus. Wing, 11.25-14.25; tail, 8.00-10.00; culmen 75- 

 .90; tarsus, 2.70-3.25; mi.ldle toe, 1.30-1.50. Fourth to tilth ,,uill 

 longest; fu-st shorter than seventh. Outer webs of the primaries with 

 quadrate .spot.s ol' whitish; lesser wing-coverts ilark rufous; lower 

 parts rufous more or less barred with whitish, or whitish spotted longi- 

 tudinally with dusky. Adult. Head, neck, lesser wing-eoverts, and 

 lower parts deep rulbus, tlie lower parts more or less barred posteriorly 

 with whitish. Primaries and tail black; the former with quadrate .spots 

 of pure white on the outer webs, and- the latter crossed by si.x narrow 

 bands of pure white, and tipped with the same. Yoiinij. Head, ne(;k, 

 and lower parts whitish, usually more or less tinged with ochraceous| 

 and with longitudinal markings of dusky. Primaries and tail dusky ; 

 the former mostly ochracoous anterior to the sinuation of their outer 

 webs, the latter crossed by numerous narrow bands of jiale grayish- 

 brown, these becoming paler and more oehiaceous toward the base. 

 Lesser wing-coverts more or less tinged with darx rufous. 



Adnlt. Lower parts light rufous barred with white. Young. 

 White prevailing on the lower iiarts. Hub. Eastern Province of 



the United States ym: I h, e at u s. 



Adult. Lower parts deep dark rufous, almost free from bars, except 

 posteriorly. Youny. Dark spotting on the lower parts pre- 

 dominating, fidb. Pacific Province, and southern Western Prov- 

 ince, of the United States \ai: el egans. 



b. Form robust and heavy, the tarsus stout; tail of the adult with a sub- 

 terminal band of black broader than the other. 



5. B. borealiB. Wing, 13.25-17.75; tail. 8.50-11.30; cuhnen, .00- 

 1.15; tarsus, 2.70-3.40; middle toe, l.GO-1.95, Weight, 2^ to 4 lbs. 

 Third to fifth quill longest; first shorter than seventh and shorter than 

 tenth. Colors extremely variable, ranging from entirely pure white 

 beneath, througli various shades of ochraeeous and rusty, and greater 

 or less amount of darker .spoUs and bars, to an entirely uniform brownish- 

 black. Adult. Tail deep rufous, generally paler at the tip ; with oi- 

 without black bars. Yoimg. Tail grayish-brown, crossed l)y nine or 

 ten bands of black, much narrower than the gray ones. Lower parts 

 always with white predominating. 



Tiliiie and lower tail-coverts without transverse bars, at any age. 

 Lower parts with white always predominating. Tail never with 

 more than one liar of black. 



Feathers of the head and neck edged laterally with rufous ; 

 scapulars and wing-coverts much variegated with whitish; 

 vol,. ii[. 33 



