60 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Plumage mid coloration. — Feathers of upperparts distinctly outlined, 

 rather broad, with rounded tips ; those of underparts more blended 

 (except anteriorly, where narrower) and with thickened and rigid shafts, 

 except on thighs, where soft but broad and rounded, and on abdomen 

 and under tail coverts very soft and downy. Adults with neck, back, 

 scapulars, and wing coverts and upper tail coverts glossy blue-black, rump 

 dull sooty black, abdomen, under tail coverts plain sooty, foreneck, chest, 

 and breast dull white with blackish shaft streaks. Sexes alike in color. 



Range. — High mountains of Guatemala (Volcan de Fuego, Cerro 

 Zunil, etc., mostly above 7,000 feet) and adjacent parts of Chiapas. 

 (Monotypic.) 



OREOPHASIS DERBIANUS Gray 



Horned Guan 



Adult male. — Culmen as far as the nostril, forehead, and crown ante- 

 rior to the cylindrical coronal casque, lores, cheeks, auriculars, chin, and 

 upper throat glossy velvety black ; crown posterior to the casque, occiput, 

 hindneck, and sides of neck black with a dark ivy-greenish sheen ; scapu- 

 lars, interscapulars, upper wing coverts, and upper tail coverts black with 

 a pronounced dark blue to dark greenish-blue sheen ; remiges black with a 

 faint bluish sheen on the outer and a faint purplish one on the inner webs ; 

 lower back and rump like the interscapulars but with so much of the dark 

 sepia to clove-brown bases of the feathers showing (or the bluish-black 

 areas so restricted to the terminal parts of the feathers) as to give these 

 areas a much-mottled appearance; rectrices black with a bluish to dark 

 purplish-bluish sheen, and crossed by a broad band of white (40 mm. 

 wide) a little less than halfway out from their bases (the distal border 

 of the white band being almost at the middle of the length of the tail) ; 

 middle of throat almost entirely nude, with a very few small blackish 

 feathers, extreme lower throat, breast, and anterior abdomen white, 

 each feather with a dusky shaft stripe of chaetura drab, the postero- 

 lateral feathers of this area washed with pale Saccardo's umber to pale 

 Dresden brown, the shaft streaks broadest on the lateral feathers; rest 

 of abdomen, sides, flanks, thighs, and under tail coverts mummy brown 

 to fuscous, some of the abdominal feathers with desiccated whitish tips 

 and washed and edged with buffy brown around the vent, the sides and 

 flanks more or less glossy with greenish blue; under wing coverts dark 

 mummy brown with some greenish-blue sheen; the casque is straight, 

 slopes backward, and is fairly slender but tapering (18 mm. in diameter 

 at base and 5 mm. at tip), with occasional hairlike blackish feathers 

 very sparsely scattered over it, the casque 55 mm. high in front, 37 mm. 

 in back ; casque, tarsi, and toes orange-red to deep vermilion ; bare eye 

 ring purple; bill pale straw color; iris white. 



