446 Annals of the Carnegie Museum. 



d. Chest and breast nearly uniform black ; thighs slightly barred with 

 white. Spizaetus tyrannus, $ and 9 > adult. 



dd. Under parts strongly barred with black and white. 



e. Feathers of crest black (except at extreme base). 



f. Chest white, crown buff-white, mixed with black. 



Spizaetus ornatus, juv. 

 ff. Sides of chest and sides of neck tawny ; a black malar 

 streak extending to breast, enclosing a pure white area ; 

 crown black, nape tawny-brown. 



Spizaetus ornatus, adult. 



ee. Feathers of crest white basally, tipped with black, crest shorter; 



chest black, rest below brownish-black, brokenly barred with 



white. Spizaetus tyrannus, juv. 



cc. Tarsi not wholly feathered. 



d. Tail equal to wing in length, or longer, or else wing not exceeding 

 it by more than length of hind toe with claw. 

 e. Size small (wing not over 170) ; wing exceeds tail by length of 

 hind toe and claw ; under parts more or less barred. 

 f. Under parts buff-ochraceous, more or less barred with 

 black. 

 g. Only chest and upper breast brokenly barred. 



Micrastur interstes, juv. 

 gg. Entire lower parts coarsely barred. 



Micrastur interstes, immature. 

 ff. Under parts (except throat) finely and evenly barred with 

 blackish and white. Micrastur interstes, adult. 



ee. Size larger (wing not less than 250). 



f. Tail a little longer than wing ; buff- white below, coarsely 

 barred with sooty-black. 

 g. A buff nuchal collar. Micrastur brachypterus, juv. 

 gg. No buff nuchal collar. Micrastur mirandollei, juv. 

 ff. Tail a little shorter than wing. 



g. Buff-white below, with elongated tear-shaped spots 

 of sooty-brown ; grayish-sooty above, feathers 

 largely edged with rufous. Accipiter cooperi, juv. 

 gg. White below, brokenly and irregularly barred with 

 chestnut-rufous and with shaft-streaks of dusky ; 

 grayish-plumbeous above, crown black. 



Accipiter cooperi, adult. 

 dd. Tail at least two-thirds the length of wing. 



e. Size large (wing 446 to 570) ; a pendant nuchal crest. 



f. Chest black, breast and abdomen white ; thighs barred 

 with black (wing 570). Thrasa'ilus harpyia. 



ff. Chest brownish-gray, rest below buff-ochraceous, barred 

 with chestnut-rufous (wing 446). 



Morphnus guianensis . 

 ee. Size smaller (wing not more than 350 mm.). 



