Subfamily FALCON INvE. Falcons. 



Ctenus FALCO Linn.eus. 



Subgenus HIEROFALCO Cuvier. 



FALCO ISLANDUS Bulnn. 



15L White Gyrfalcon. (:5r,:5) 



One of the largest and most jxiwei-ful of tlie FuIcohIiiii'. Feet, very stout : 

 tarsus, ratliei- longer than the middle toe witliout elaw, feathered fully half way 

 down in front an<l on sides, with nai-row bare sti-ip behind ; elsewhere, seticulate. 

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

 the first decidedly emarginate on inner weh. Tail, rounded; sexes, alike, 

 roiwf/. — Little different. Wing of male, 13.r)()-14. ,")(» ; tail, 8. .50-9. 50. Wing 

 <if female, lo-Ki; tail, 9-10. Adii/fs: — (ieneial plumage of upper j)aits, l)arred 

 with dark brown and pale ash, the former jn-edominating, es))ecially on the 

 head and neck; tail, closely barred \vitli light and dark in about equal amounts; 



