110 BIRDS. 



VuUurince)^ no ear tufts. Base of stout, strongly hooked 

 bill, not hidden by feathers. Claws very strong and sharp. 

 Plumage usually of blended colors, barred or streaked; 

 changes considerable; $ usually the larger. Genera fifty, 

 species three hundred, abounding every vv^here. Their 

 habits are too well known to require description here. 



I. Tarsus feathered to the toes. 



a. Tarsus entirely feathered ; tail 12 or more. . Aquila, 12. 



aa. Tarsus with a narrow unfeathered strip behind ; tail less 

 than 12 Arcuibuteo, 11. 



II. Tarsus reticulate all around. 



h. Upper mandible toothed; under notched; nostrils circular. 



Falco, 1. 



hb. Tail widely forked ; outer feather twice as long as middle 

 ones; colors black and white. . . Elanoides, 3. 



hhh. Claws all of same length, rounded beneath; tibial feathers 

 close ; plumage compact, without after shafts. Paxdiox, 2. 



hbhb. Tail emarginate, and outer feather not longer than middle; 

 head and tail white in adult. . . . Elanus, 5. 



III. Tarsus scutellate in front only (occasionally "booted.") 



c. Toes not webbed at all ; neck feathers lanceolate, white in 

 adult Haliaetus, 13. 



cc. Toes somewhat webbed at base. 



d. Nostrils circular; tail less than f length of wing. 



ICTINIA, 4. 



dd. Nostrils oval ; tail more than | length of wing. 



e. Tarsus feathered about half way down in front, the 

 feathers scarcely separated behind. . Astur, 7. 



ee. Tarsus feathered less than one-third down in front, the 

 fciithers widely separated behind. . Accipiter, 8. 



IV. Tarsus scutellate in front and behind. 



/. Face with a slight ruff; tarsus twice length of middle toe; 



upper tail coverts white Oircus, 6. 



ff. No ruflf ; 3 or 4 outer primaries emarginate ; rump not white. 



BUTEO, 10. 



