66 Field Museum of Natural History — Zoology, Vol. IX. 



* GROUP 4. Wing, 8.50 to 10 inches long. 



SECTION 1. Hind toes, with well defined membraneous lobe or flap; 



belly, white, sometimes tinged on lower part with dusky or gray; 



head, marked with more or less white, or brownish white 



Head, brownish ; a patch of dull white on 

 face at base of bill; speculum, white (fe- 

 male). Marila marila. 

 Scaup Duck. Bluebill. Blackhead. 



See No. 53. 



Marila marila. 



Head and neck, dark glossy green ; a nearly round patch of white 

 on cheek at base of bill; back, black; speculum, white (male). 



Clangula datigula americana. 

 American Golden-eye. Whistler. 

 See No. 56. 



Head, bluish black, or purplish blue; an irregular white patch on 

 cheek at base of bill (male). Clangula islandica. 



Barrow's Golden-eye. 



See No. 57. 



Top of head, brown; sides of head, brownish white; speculum, 

 gray; bill, more than one and a quarter inches long (female). 



Marila americana. 

 Redhead Duck. 



See No. 51. 



Bill, not over 1.25 long; a patch of white, or grayish white, on the 

 head, including the eye; no speculum; under tail covert, white; 

 adult males have the tail feathers long and pointed. Harelda hyemalis. 



Old-squaw. Long-tailed Duck. 

 See No. 59. 



SECTION 2. Hind toe, with well defined membraneous lobe or flap; 



belly, white, sometimes tinged on lower part with dusky or 



gray; no white, or grayish white, on head. 



Head, black, glossed with green; back, grayish white, finely lined 

 with black; speculum, white (male). Marila marila. 



Scaup Duck. Bluebill. Blackhead. 



See No. 53. 



* For directions for measurement, see page 21. 



