log NORTH AMERICAN BIRDS. 



1. Adult Upper paiis, i.-M:i-|itiiiy 1r-;u1 and neck, with transverse 

 crescentic bars of dark pkiinbeous ; lower parts immaculate, or 

 else without well-de(incd markings. Young. Upper parts ■with 

 longitudinal stripes of dark ]iliinibeous ; lower parts usually con- 

 spicuously striped. Ilab. Greenland (in the breeding-season) ; in 

 winter, occasionally wandering into the northern portions of 

 Europe and North America var. candicans. 



Lower tail-coverts always with markings. A tinge of ashy-blue more or 

 less prevalent above. Young dusky above. 



Head and neck above abruptly lighter than the back. Yoimg plain 

 grayish-brown above, with conspicuous whitish borders to the feathers. 



2. Adult. Upper parts white, passing into bluish posteriorly ; 

 everywhere (except on head and neck) with sharply defined, 

 transverse (not crescentic, but continuous) bars of dark i)lumbeous. 

 Abdomen and flanks with ti-ansverse spots of the same. Young 

 without irregular light mottling to the plumage above, and with 

 broad longitudinal stripes beneath. Hab. Iceland and Southern 

 Greenland, in the breeding-season ; in winter, south into North- 

 eastern United States, and Northern Europe. . var. islandicHs. 



Head and neck above abruptly darker than the back. Young (of var. 

 sacer) variegated grayish-brown above, without light borders to the 

 feathers. 



3. Adult. Top of the head streaked with whiti-sh; back with 

 sharply defined, continuous, narrow transverse bars, of creamy- 

 white. Hab. Interior regions of Continental Arctic America 

 (Slave Lake, Yukon, and McKenzie River district) . . var. .lacer. 



4. Adidt. Top of head not streaked with whitish ; back without 

 sharply defined bars of the same. Hab. Continental Arctic Europe 

 (Scandinavia) and Siberia. Migrating south, in winter, to Bengal 

 (Hardwicke) var. rjyrfalco} 



h. Lower parts with dusky predominating, or wholly dusky. 



U. Adult. Almost entirely dusky, without well-defined markings 

 anywhere. Hab. Littoral regions of the Hudson Bay Territory 

 and Labrador ........ var. lab r ado r a. 



2. F. lanarius. Wing, 11.50 -IG.OO; tail, G.G0-9.n0; culmen, .70-1.00; 

 tarsus, 1.90-2.40; middle toe, 1.65-2.00. Ground-color varying from pale 

 grayish-plumbeous to dark sepia-brown ; beneath white, with sparse markings, 

 these coalesced into a broken patch on the flanks. Adult. Above obscurely 

 barred transversely with pale ashy and brownish-dusky, the former prevailing 

 posteriorly, the latter anteriorly ; a lighter nuchal band. Spots on the sides and 

 flanks transverse. Young. Above brown, varying from grayish-drab to dark 

 sepia, the feathers usually bordered with paler (rusty in youngest individuals) ; 

 markings beneath all longitudinal. 



a. Outer webs of tail-fealliers with large well-defined light spots; outer 

 webs of the primaries sometimes with light spots on the basal portion; 



1 Falco gyrfalco, var. (njrfalco (LiXN.). Falco rj);r/alco, Lixx. S. N. 1 766, p. 130. — Gmel. S. N. 

 275. — ScHi.r.G. I!pv. Crit. II, Tr. de Fauc. p!. iii ; F. van Nederl. Vog. pis. iii and iv. — 

 X.4VM. Vog. )il. cccxci. Hierofdlco gijrfulco, SciiLEo. Boxap. Rev. Zool. 1854, 535. — Newton, 

 Ootlieca WoUeyana, I, 87, pi. c. F. gtjrftUco norvecjicits, Wolley. Falco gyrfalco nortccgicus, 

 SciiLEG. llus. Pays-Bas, 1862, 12. Fulco candicmui, var. y, Blas. 



■\Viiig, 13.00 -14.,50 ; tail, 9.30 ; culmen, .93 ; tarsus, 2.50 ; middle toe, 1.92. 



