KEY TO DUCKS, GEESE AND SWANS OF NOETH AMERICA. 17 



Section 3. Hind toe with well defined membraneous lobe 



or flap; belly, white. 



Head, greenish purple, no white on head; hacli, 

 barred black and white ; speculum, white. 



Lesser Scaup Duck, Blue-bill. 



Aythya affinis {male). 

 See page 57. 



Aythya affinis. 



Head, brownish ; a patch of dull white at base of bill ; no white on ear coverts ; 

 speculum, white. 



Lesser Scaup Duck, Blue-bill. 



Aythya affinis (female). 

 See page 57. 



Head, greenish purple; no white on head; back, dull black; speculum, gray. 



Ring-neck Duck. 



Aythya collaris (male). 

 See page 58. 



Head, dull brown; brownish white at base of bill and below eye; speculum, 

 gray. 



Ring-neck Duck, 

 Aythya collaris (female). 

 See page 58. 

 Head, greenish purple ; a large patch of white on back of head. 



Buffle Headed Duck. 

 Charitonetta albeola (male). 

 See page 61. 

 Head, dark brown or dusky, a patch of white behind the eye (on ear coverts) ; 

 no white or brownish white at base of bill; speculum, white. 



Buffle Headed Duck. 

 Charitonetta albeola (female). 

 See page 61. 



Section 4. Hind toe with well defined membraneous lobe 

 or flap; belly, not white. 



Plumage variously marked with white, slate color and chestnut. 



Harlequin Duck. 

 Histrionicus histrionicus (male). 

 See page 66. 

 General plumage dull brown, mottled on the under parts. 



Harlequin Duck. 

 Histrionicus histrionicus '' female). 

 See page 66. 



