Carriker : List of the Birds of Costa Rica. 449 



gg. Breast, abdomen and thighs chestnut (wing 235). 



Falco deiroleucus. 

 ff. Throat and chest slaty-black, rest below grayish-white, 

 finely barred with blackish ; slaty above (wing 360). 



Leucoptemis princeps. 

 ee. Throat and upper chest either streaked or barred. 



f. Upper parts bluish-gray, with faintly indicated bars of 

 paler, entire under parts (except upper throat) finely 

 barred with slaty gray and white. 



Asturina p/agiata, adult. 

 ff. Upper parts mainly sooty-brown, or brown. 



g. Interscapular region and chest buff, barred with 

 black ; breast and thighs black ; tail extensively 

 white basally. Polyborus cheriway, 



gg. Interscapular region concolorous with back ; breast, 

 abdomen, and thighs buff- white, coarsely and 

 brokenly barred with dark chestnut-rufous; chest 

 heavily mottled with same. Buteo plotypterus. 



dd. Under parts mottled or streaked but not barred (except sometimes 

 on thighs). 

 e. Dorsal aspect of tail chestnut, or else chest dusky chestnut- 

 rufous, with rest of lower parts mainly white (wing 380). 

 f. Tail chestnut; lower parts (except throat, white) buff- 

 ochraceous, mottled with sooty-brown. 



Buteo boreaiis costaricensis, adult. 

 ff. Chest brown, rest below white. Buteo swainsoni, adult. 

 ee. Dorsal aspect of tail not chestnut or brown. 



f. Under tail-coverts white or buff-ochraceous, unmarked, or 

 else upper tail-coverts and base of tail whitish. 

 g. Upper tail-coverts and base of tail whitish ; lower 

 parts whitish, throat narrowly, and breast broadly, 

 streaked with dark brown ; flanks almost entirely 

 brown. Rostrhamus sociabilis, juv. 



gg. Under tail-coverts white or buff-ochraceous. 



h. Median portion of outer web of primaries cinna- 

 mon-ochraceous, barred with black, apical 

 portion sooty-black ; pileum and nape buff- 

 white, streaked with sooty. 



Asturina plagiata, juv. 

 hh. Whole outer web of primaries sooty-black. 



i. Inner web of three outer primaries emargi- 

 nate ( wing, 400) ; lower parts but slightly 

 mottled with dusky. 



Buteo swainsoni, juv. 



it. Inner web of four outer primaries emarginate. 



j. Smaller (wing, 280); buff below, sides 



of chest and throat streaked, abdo- 



