334 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. IX. 



Distr.: Northern hemisphere, breeding chiefly (in North America) 

 from North Dakota to Alaska and casually to the Gulf of St. Lawrence. 

 The greater number go south in winter to the Gulf states, Mexico, and 

 the West Indies. 



Adult male: Head and neck and upper breast, black, showing green- 

 ish reflections; back, grayish white, delicately lined with fine, wavy 

 lines of black, giving -it a grayish appearance; 

 ^gflH^^ speculum, white; under parts, white, the lower 



belly showing grayish tinge. Length, 19; wing^ 

 ^^~^^H m 8.50; tarsus, 1.50, bill, 2. 



*^*^ Adult female: Patch at 



Jgl ^j[ ^P^H^ tne base of the bill, white or 



J|p J^Sfcfc *Y;'" r ^ grayish white; rest of the 



Bgjfa >lf head and neck > breast, and 



sH 'm upper back, brownish; belly, 



IpC .,''' l-'M white; speculum, white. 



cT * 9 ' Length, 17.75; wing, 8.25; 



tarsus, 1.30; bill, 1.60. 



The Scaup Duck occurs on Lake Michigan and waters in the in- 

 terior of Illinois and Wisconsin during the migrations. More or less 

 common, varying in different seasons, but rare in comparison with 

 next species. 



54. Marila affinis (EYTON). 

 LESSER SCAUP DUCK. 



Aythya affinis (Eyt.), A. O. U. Check List, 1895, P- 53- 

 Local name: Bluebill. 



Distr.: North America in general, breeding chiefly north of the 

 United States; south in winter to the Gulf coast and West Indies, 

 Mexico, and Central America to Panama. 



Adult male: Resembles the male of the preceding species, but is 



somewhat smaller in size; the head generally shows a faint gloss 



of purplish, which in the Scaup Duck is usually 



^flj^t greenish, and the wavy black bars on the flanks 



JZ. t^ are more distinct and heavier; speculum, white. 



''&jjlr' Length, about 17; wing, about 8.10; tarsus* 



:|p^pgk J-S ; bill, 1.75. 



-' T %^ Adult female: Similar to the female of the pre- 



sO" l|k ceding species, except that it is smaller. 



^ The white speculum (band on the wing) will 



JsSf -A always distinguish this species in any plumage from 

 the Ring-necked Duck, which has the speculum gray. 

 Length, about 16.25; wm > about 7.75; bill, about 1.55. 



