110 BIRDS. 



) 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 where. 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 uufeathered strip behind ; tail less 

 than 12 ....... ARCHIBUTEO, 11. 



II. Tarsus reticulate all around. 



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



FALCO, 1. 

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



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

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



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

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



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



III. Tarsus scutellate in front only (occasionally &quot;booted.&quot;) 



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 length of wing. 



ICTINIA, 4. 



dd. Nostrils oval ; tail more than I 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 



feathers widely separated behind. . ACCIFITEK, 8. 



IV. Tarsus scutellate in front and behind. 



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



upper tail coverts white ..... CIRCUS, 6. 



ff. No ruff; 3 or 4 outer primaries einargiuate ; rump not white. 



BUTEOj 10. 



