Subfamily FALCONING. Falcons. 



Gexus FALCO Linn.eus. 



Subgenus HIEROFALCO Cuvier. 



FALCO ISLANDUS Buunn. 



151. White Gyrfalcon. (-''O-S) 



One of the largest and most powerful of the Falroiiiiuc Feet, very stout; 

 tarsus, rather longer than the middle toe without claw, feathered fully half way 

 down in front and on sides, with narrow bare strip behind; elsewhere, seticulate.. 

 Wing, pointed by second quill, supported nearly to the end of the third, only 

 the first decidedly emarginate on inner web. Tail, rounded; sexeg, alike. 

 rom(f/.-— Little difi'erent. Wing of male, 13.50-14.50; tail, 8.50-9.50. Wing 

 of female, 15-16 ; tail, 9-10. .4(/»i'^.s.— (xeneral plumage of upper part.?, barreill 

 with dark brown and pale ash, the former predominating, especially on the 

 head and neck ; tail, closely barred with light and dark in about equal amounts : 



