160 KEY TO THE WATER BIRDS OF FLORIDA. 
Aythya vallisneria. 
Length, 21; Wing, 8.40; Tarsus, 1.60; Bill, 2.20. 
Head rufous brown; speculum grayish ; upper 
feathers edged with black; the rest narrowly 
tipped with white. (See figure showing difference . 
in bill from Canvas-back.) 
Length, 20.50; Wing, 8.30; Tarsus, 1.60; Dill, 2.20. 
Head grayish brown; speculum grayish; upper 
feathers edged with black; the rest narrowly 
tipped with white. Closely resembles female of 
Ring-neck Duck (A. codlaris), but is larger. 
Length, 19; Wing, 8.50; Tarsus, 1.50; Bill,2. Head 
black glossed with green; back grayish; specu= 
lum white. 
Length, 17; Wing, 8.10; Tarsus, 1.50: Bill, 1.80. 
Similar to the preceding species, from which it 
differs only in being somewhat smaller; head black 
with purplish gloss; speculum white. 
Aythya affinis. 
Aythya americana (male). 
Redhead Duck. See page 226 
Aythya americana (female). 
Redhead Duck. See page 226 
Aythya marila nearctica (male). 
Greater Scaup Duck. 
Bluebill. See page 228 
Aythya affinis (male). 
Lesser Scaup Duck. 
Bluebill, See page 
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