Jan., 1909. Birds of Illinois and Wisconsin — Cory. 63 



Front of head, including cheeks, black (adult ) ; head with black 

 stripes on side (female or immature). Tropical species, accidental 

 in the United States. Nomonyx dominicus. 



Masked Duck. 



See No. 67. 



* GROUP 2. Wing, from 6.50 to 7.50 inches long. 

 SECTION 1. Belly, white. 



Head, greenish purple, no white on head; back, barred black and 

 white; speculum, white (male). Marila affinis. 



Lesser Scaup Duck. Blue-bill. 



See No. 54. 



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

 on ear coverts; speculum, white (female). 



Marila affinis. 

 Lesser Scaup Duck. Blue-bill. 



See No. 54. 



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

 speculum, gray (male ) . Marila coUaris. 



Ring-necked Duck. 



See No. 55. 



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

 speculum, gray (female ) . Marila collaris. 



Ring-necked Duck. 



See No. 55. 



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

 (male ) . Charitonetta albeola. 



Buffle-headed Duck. 



See No. s8. 



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 (female). Charitonetta albeola. 



Buffle-headed Duck. 



See No. 58. 



* For directions for measurement, see page 21. 



