FAMILY FORMICARIIDAE 



193 



Description. — Length 145-160 mm. Adult male, with forehead and 

 side of head bare, in many the entire crown with only scattered hair- 

 like filaments and feather shafts without webs, the skin bright blue; 

 a concealed area of white in center of back in some, reduced or absent 

 in others ; entire plumage black ; wing coverts and tail tipped with 

 white, the latter marking often reduced or absent through wear; 



Figure 17. — Bare-crowned ant-bird, hormiguero frentipelado, Gymnocichla 

 nudiceps, male left, female right. 



alula and outermost primary white ; inner wing coverts partly white ; 

 under surface of primaries and secondaries edged with white. 



Adult female, forehead feathered (in definite contrast to the male), 

 only the lores and area around eye bare ; upper surface and flanks 

 from olive-brown to light or dark russet-brown (according to the sub- 

 species) ; concealed white on back present or absent, as in males; 

 outer webs of primaries and secondaries, and tips of wing coverts, 

 brighter brown ; tail blackish brown ; under surface, including under 

 wing coverts lighter, brighter brown ; inner margins of primaries 

 and secondaries on under surface, buffy white to cinnamon-buff. 



Immature male, forehead more or less feathered, with only the 



