64 Field Museum of Natural History — Zoology, Vol. TX. 



SECTION 2. Belly, not white. 



Plumage, variously marked with white, slate-color, and chestnut 

 (male). Histrionicus histrionicus . 



Harlequin Duck. 

 See No. 6o. 



General plumage, dull brown, mottled on the under parts (female ) . 



Histrionicus histrionicus. 

 Harlequin Duck. 

 See No. 60. 



* GROUP 3. Wing, from 7.50 to 8.50 inches long. 



SECTION 1. Head, marked with more or less white or brownish 



white; belly, white, sometimes tinged with dusky or 



gray on lower part. 



Head, brownish; a patch of dull white on 

 face at base of bill ; speculum, white (female ) . 



Marila marila. 

 Scaup Duck. Bluebill. 



See No. 53. 



Speculum, white, similar to preceding but somewhat smaller (fe- 

 male). More common in the South than the Greater Scaup Duck. 



Marila affinis. 

 Lesser Scaup Duck. 

 See No. 54. 



Speculum, gray; head and neck, brownish; chin and anterior 

 portion of lores, brownish white or whitish (female); resembles fe- 

 male Red-head, but is smaller. Marila collaris. 



Ring-necked Duck. 

 See No. 55. 



A patch of white or grayish white on the, head, including the eye ; 

 no speculum; under tail coverts, white; adult males have the tail 

 feathers long and pointed. Harelda hyemalis. 



Old-squaw. Long-tailed Duck. 



See No. 59. 



*For directions for measurement, see page 21. 



