FALCOKID.E — THE FALCONS. 323 



1. H. pelagicus.' Wing, 24.50-20.00; tail, 13.50-16.00; culmen, 

 2.00; ilri>ili ul' bill, 1.80; cere, on top, 1.10; tarsus, 3.50; micUlle too, 

 2.95. Adult. Forehead, greater wing-coverts, abdomen, and tail, white; 

 other portions blackish-brown (Auct.). Young. Dark umber or black- 

 ish-brown, the feathers of the head and neck with lighter shaft-streaks; 

 tertials (except at ends) and basal third, or more, of iimei- webs of tail- 

 feathers, white; tail-coverts much mixed with the same. Hub. North- 

 eastern Asia. 



B. Tail of twelve feathers, only .sliglitlj- rounded. Lower end of the nostrd 

 rounded, opening more abruptly inward ; upper outline of the cere nearly 

 straight; lores scantily feathered. 



2. H. albicilla. Wing, 23.00-28.00 ; tad, 11.50-10.00; culmen, 2.05- 

 2.20; tarsu-s 3.30 - 3.80 ; middle toe, 2.50-2.95; depth of bill about 

 1.45 ; cere, on top, .85. Adidf. Head and neck pale grayish-fulvous, 

 or dirty yellowish-gray, not abruptly lighter than the body. Tail, 

 onlv, pure white. Rest of the plumage, including the tail-coverts, 

 dark grayish-brown, inclining to blackish on the primaries. Young. 

 Prevailing tint of the upper parts light isabella-color, or pale grayish- 

 cinnamon, each feather having a terminal triangular spot of blackish- 

 brown. Breast soiled white, with broad stripes of brownish-black; 

 rest of the lower parts nearly uniform fulvous-brown, the tibise darker. 



. Hah. Europe ; Egypt ; Greenland. 



3. H. leucocephalus. Wing, 20.00-20.00; tail, 10.50-15.50; cul- 

 men, 1.85-2.21): tarsus, 2.05-3.70; middle toe, 2.35-3.10; depth 

 of bill about 1.30; cere, on the top, .80. Adult. Head and neck, 

 tail and tail-coverts, p\u'e white, immaculate (except in transition 

 dress). Rest of the plumage brownish-black. Young. Brownish-black, 

 showing much concealed white at the bases of the feathers; ground- 

 color inclining to umber-brown on the upper surface ; on the lower 

 part.s, the basal white much exposed and predominating, the blackish 

 forming longitudinal, tear-shaped spots. Head and neck brownish- 

 black, the penicillated feathers of the nape seldom with whitish points. 

 Tail-feathers and primaries black, the inner webs usually more or loss 

 marked, longitudinally, with bufFy-whitish. Hab. The whole of North 

 America. 



Sp. Chak. Yomui female (T) (28,100, Amoor River ; Mr. Burlingame). Form: very similar 

 to H. albieitla and H. Icucoccphala, but bill altogether more robust, and feet rather less so, than 

 in these. Tail, of fourteen leathers ! graduated for about one half its length. Dimensions : 

 About the size of the female of the two other species. Color : Generally dusky vandyke-browii, 

 a medial line on the lanceolate feathers of the neck, and the border of the si^uamate ones of the 

 tibire, decidedly lighter. Entire plumage white at the base, this exposed wherever the feathers 

 are disarranged, and prevailing on the crissum. Tertials, basal half of inner webs of primaries, 

 the whole tail, and upper tail-coverts, ndiite with a yellowish tinge. Tertials; upper tail-coverts, 

 and tail-feathers, with a large terminal spot of clear grayi.sh-black ; on the tail these form a rather 

 irregular terminal zone, being on the middle feather narrower, and broken into fine blotches. 

 Bill, cere, lore, and feet, yellow ; end of upper mandible, and the claws, bla(?k. Wing-formula, 

 3, 4, 2, 5-6-7 = 1. Wing, 24.50 ; tail, 13.50 ; culmen, 2.G0 ; depth of bill, l.SO ; cere, ou 

 top, 1.10 ; tarsus, 3.50 ; middle toe, 2.95. 



