X BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Order Falconifoumes: Diurnal birds of prey — Continued 

 Suborder Falcones: True birds of prey — Continued 

 Family Accipitridae — Continued 



Subfamily Buteoninae — Continued P*b* 



Genns Leucopternis K&np 376 



Key to the North and Middle American forms of 



Leucopternis 378 



Leucopiernis alhicollis costaricensis Sclater 379 



Leucopternis albicollis ghieshreghti (Du Bus) 381 



Leucopternis semiplmnbea Lawrence 383 



Leucopternis plumbea Salvin 385 



Leucopternis princeps princeps Sclater 387 



Genus Hypomorphnus Cabanis 388 



Key to the subspecies of Hypomorphnus 390 



Hypomorphnus urubitinga ridgwayi (Gurney) 390 



Hypomorphnus urubitinga urubitinga (Gmelin) 393 



Genus Buteogallus Lesson 396 



Key to the species and subspecies of BuieopoZ/us 397 



Buteogallus anthr acinus anlhr acinus (Lichtensteiu) 398 



Buteogallus anthracinus cancrivorus {Clark) 403 



Buteogallus anthracinus subtilis (Thayer and Bangs) 405 



Buteogallus gundlachii (Cabanis) 406 



Genus Busarellus Lesson 409 



Busarellus nigricollis nigricollis (Latham) 410 



Genus Ur ubitornis Yerreaux 415 



Key to the races of Urubitornis solitaria 417 



Urubitornis solitaria solitaria (Tschudi) 417 



Urubitornis solitaria shejjleri van Rossem 420 



Genus Aforp/in?<s Dumont 421 



Key to the species of Morphnus 422 



Morphnus guianensis (Daudin) 423 



Morphnus taenialus Gurney 427 



Genus Harpia Vieillot 430 



Harpia harpyja (Linnaeus) 431 



Genus Spizastur Gray 437 



SpizaHur melanoleucus (Vieillot) 438 



Genus SpizaHus Vieillot 441 



Key to the forms of Spizaetus of North and Middle 



America 443 



Spizaetus ornatus vicarius Friedmann 444 



Spizaetus tyrannus (Wied) 448 



Genus Aquila Brisson 452 



Aquila chrysaetos canadensis (Linnaeus) 455 



Genus Thallasoaetus Kaup 467 



ThallasoaetU6 pelagicus (Pallas) 469 



Genus Haliaeetus Savigny 472 



Key to the American species and subspecies of Haliaee- 

 tus 474 



Haliaeetus albicilla albicilla (Linnaeus) 475 



Haliaeetus albicilla groenlandica Brehm 482 



Haliaeetus leucocephalus leucocephalus (Linnaeus) 483 



Haliaeetus leucocephalus washingtoniensis (Audubon) 489 



