BIRDS OF NORTH AND MIDDLE AMERICA 213 



tions. One subgenus, Geranoaetus, is extralimital and may be disposed 

 of more briefly than the others. 



Plumage and coloration. — Plumage compact, full; primaries and rec- 

 trices moderately rigid; underparts white, plain or narrowly barred 

 with dark gray in adults ; upperparts dark; young difi'erent from adults. 



Range. — Nearly cosmopolitan, but absent in the Indo-Malayan and 

 Australian regions and in Oceania. (Many species, about 12 in North 

 and Middle America.) 



There is much variation in external characters among the numerous 

 species of this genus, as here defined, and the group defies subdivi- 

 sion; I am unable to see valid reasons for the recognition of Buteola 

 and Tachytriorchis as genera if all the remaining species are left in 

 Buteo. Scarcely any two species of the group are more unlike struc- 

 turally than B. albicaudatus and B. albonotatus, both of which belong to 

 the "genus" Tachytriorchis according to Sharpe. Similarly the 

 "genus" Coryornis cannot be maintained if B. lineatus be left in Buteo 

 (cannot be regarded even as a subgenus). Also Brewsteria and 

 Butaetes both merge with Buteo, and so on.* In order to satisfy all 

 doubts on this score illustrations and descriptions are here included of 

 these "subgenera." 



KEY TO THE SPECIES AND SUBSPECIES OF BUTEO » 

 a. Tarsi feathered to toes. 



b. Bill at base measuring 42-48 mm., from angle to angle of gape (western 

 North America) ("subgenus Brewsteria") 



c. Entire bird fuscous-brown, exept tail B. regalis, dark phase (p. 226) 



cc. Underparts v/hitish. 



d. Thighs heavily barred with rufescent; abdomen more or less so. 



Buteo regalis, light phase, ad. (p. 226) 



dd. Thighs pure white like rest of underparts B. regalis, juv. (p. 227) 



66. Bill at base measuring 33-38 mm. from angle to angle of gape. 



("subgenus Butaetes") 

 c. Entire bird fuscous-brown; tail tipped and obscurely banded with white 

 (northern North America south to Southern United States). 



B. lagopus s.-johannis, dark phase (p. 327) 

 cc. Underparts whitish marked with dark brown. 



d. Abdomen crossed by a very broad unbroken blackish band; terminal 

 half of tail unbarred except for white tip. 

 e. Size smaller, wing under 430 mm. 



B. lagopus s.-johannisj juv. (p. 328) 



* Extralimital subgenus Geranoaetus Kaup. — Size much larger than Buteo, 

 wings 450-575 mm.; tail graduated and proportionately shorter, only about hal. 

 as long as wing; the five outer primaries emarginate on their inner webs, the third 

 and fourth (from the outside) longest, the first between the sixth and the seventh 

 (from the outside) in length; nostrils obliquely horizontal; feet as in typical Buteo. 

 Range. — South America. (Monotypic.) 



" This key includes only forms known to occur in the regional limits involved 

 in this work plus a few extralimital forms of closely adjacent areas that may be 

 expected to occur at times. 



