400 ANATID^. 



Above sooty brown, beneath paler ; bill 

 ■wholly dusky, the basal half of the culmen 

 level, or scarcely if at all elevated at base . nigra, p. 401. 

 b'. Nail of bill less flattened, somewhat arched, 

 and hooked at tip. Adult male : J3asal 

 half of upper mandible, including whole 

 knob, yellow or orange ; rest, including 

 entire edge, black. Adult female : Above 

 dusky greyish brown, the feathers of dorsal 

 region with paler tips ; bill uniform 



blackish mnericana, p. 404, 



b. Length of commissure much more than length 



of inner toe without claw. 



c'. Feathering of head advancing farther forward 



on lores than on forehead ; wing with a 



white speculum (Melanetta). 



c". Loral feathers separated from nostril by 



a space nearly or quite equal to length of 



nostril. Adult male : Lower part of 



swollen basal portion of upper mandible 



on sides unfeathered ; basal portion of 



culmen elevated, but not forming an 



abrupt knob ; plumage black, also on the 



flanks. Adtdt female : Sooty greyish, or 



dusky greyish brown, darker above ; no 



white on head . fusca, p. 40C>. 



d". Loral feathering separated from nostrils 



by a space much narrower than length 



of nostril. Male with swollen lateral 



base of upper mandible entirely feathered. 



d" '. Lateral outlines of bill convex ; knob 



of the male with anterior outline 



sloping backwards ; plumage black, 



but flauks olive-brown deglandi, p. 409. 



e'". Lateral outlines of bill nearly parallel ; 

 knob of mcde very high, with anterior 

 outline concave and the upper one 

 horizontal, the top forming a con- 

 spicuous projection ; plumage black, 



no olive-brown colour on flanks carbo, p. 411. 



d'. Feathering of head advancing much farther 

 forward on forehead than on lores ; sides 

 of bill at base with swollen portion en- 

 tirely naked ; wing without speculum (Pe- 

 lionetta). Adtdt male : Uniform deep 

 black, but a patch on the top of the head 

 and another on the hind neck pure white 

 (one or the other of them occasionally 

 absent) ; bill reddish in life, the swollen 

 base, on each side, marked with a large 

 black spot. Adult female : Resembles 

 the females of tE. fusca, deglandi, and 

 carlo, but easily distinguished by the 

 difi"erent feathering on head, by the naked 

 swellings at the base of the sides of the 

 biU, and by the much darker black colour 

 of the upper part of the head perspicHlata, p. 412. 



