NATURAL SCIENCES OF PHILADELPHIA. 89 



ON THE BUTEONINE SUBGENUS CRAXIREX, GOULD. 

 BY ROBERT RIDGWAY. 



The genus Buteo as restricted 1 is divided primarily into two 

 very distinct groups, one (typical Buteo) having four and the other 

 (Craxirex) having only three of the outer primaries emarginated 

 on their inner webs. The European B. vulgaris, Leach, the type 

 of the genus, belongs to the first group ; its American allies are B. 

 borealis (Gm.), B. harlani (Aud.), B. cooperi, Cass., B. lineatus 

 (Gm.), B. abbreviates, Caban., B. minutes, Pelz., and B. brachyura, 

 Vieill.; while the Old World contains more numerous representa- 

 tives of the subgenus. 2 The subgenus Craxirex is peculiar to 

 America, the majority of the species belonging to the southern 

 continent. North America possesses only C. swainsoni, Bonap., 



1 At present we exclude from the genus Buteo the closely related forms 

 named respectively Heteraetus, Kaup (type Spizaetus melanoleucus, Vieill.), 

 Urubitinga, Lafr. (type Falco urubitinga, Gm. = JJ. zonura [Shaw]), 

 Heterospizias, Sharpe (type Falco meridionalis, Lath.), Antenor, Ridgw. 

 (type Falco unicinctus, Temm.), Buteogallus, Less, (type Falco cequinoc- 

 tialis, Gm.), Leucopternis, Kaup (type Falco melanops, Lath.), Asturina, 

 Vieill. (type Falco nitidus, Lath.), Rupomis, Kaup (type Falco magniros- 

 tris, Gm.), OnycJwtes, Ridgw. (type 0. gruberi, Ridgw.), Urubitornis, 

 Verr. (type Circaetus solitarius, Tschudi), and Harpy haliaetus, Lafr. (type 

 Harpyia coronata, Vieill.). Busarellus, Lafr. (type Falco nigricollis, 

 Lath.), placed in most of the systems in close proximity to Buteogallus, and 

 often in the same genus, we consider to be far removed from any of the 

 above genera, being more closely related to the Haliaetine forms, especially 

 to Oypoictinia, Kaup (type Buteo melanosternon, Gould), of Australia. 



2 The synonymy of this subgenus is as follows : 



Buteo, Cuvier, Lee. Anat. Comp. I., tabl. Ois. 1800 (type, Falco buteo, Linn., 



= B. vulgaris, Leach). 

 Butaquila, Hodgs., Gray's Zool. Misc. 1844, 81 (type, Falco ferox, Gm.). 

 Buteola, Bonap., Comp. Rend. XLL, 1855, 651 (type, Buteo brachyura, 



Vieill.). 

 Pterolestes, Sund., Disp. Ac. Hemeroharp., 1874,23 (types, Falco jakal, 



Daud., and Buteo augur, Rupp.). 

 B. {Craxirex) Swainsoni has been usually regarded as the American 

 analogue of the B. vulgaris, of Europe ; but B. lineatus is, in reality, the 

 nearest New World relative of the latter, agreeing very closely in size, pro- 

 portions, and details of structure, though very different in color. B. borealis 

 is also strictly congeneric with these two typical species. 

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