AVES FALCONID^C. 



559 



Back: Interscapular region, back, rump and upper tail-coverts dark 

 seal-brown, barred with isabelline or buffy white; the dark color pre- 

 ponderates on the upper back and the light color on the rump and upper 

 tail-coverts. 



Fio. 279. 



Polyborus plancus. P. U. O. C. 7894. Adult male. Details of head. Natural size. 



Tail : Pale isabelline or buffy white, with a broad terminal band of deep 

 seal-brown ; the light part of the tail crossed by many, twelve or more, 

 narrow deep seal-brown bars ; the light color predominates on this part 

 of the tail. 



Wings : Primaries dark seal-brown at their tips ; the remainder white 

 or isabelline, freckled and vermiculated on their upper surfaces with dark 

 seal-brown ; on their inferior sides immaculate buffy white, or isabelline ; 

 the shafts dull ivory-white; the secondaries somewhat lighter in shade 

 than the terminal seal-brown of the primaries and with buffy white tips 

 very narrow and sometimes obsolete ; scapulars and median wing-coverts 

 dark seal-brown, barred with narrow isabelline or buffy white ; rest of the 

 upper wing-coverts dark seal-brown, with more or less obsolete barring of 

 a fainter shade; under wing-coverts and axillaries uniform dark seal- 

 brown, sometimes barred obsoletely with lighter shades of the same 

 color. 



