Anatine Genus Nyroca and Its Nearest Allies. 113 
one of the most easily separated groups of those now under consideration. 
Some of its characters are here for the first time elucidated. 
Its only species is Aristonetta valisineria (Wilson). 
The following key to the genera here treated is added for convenience of 
reference and as a more graphic exposition of salient characters. 
ANALYTICAL KEY TO GENERA ALLIED TO NYROCA. 
ae. 
Length of exposed culmen about equal to length of inner toe with claw. 
bt. Base of culmen deeply concave; anterior outline of feathering at 
base of culmen acutely pointed; feathering on sides of maxilla not 
reaching anteriorly as far as that at base of culmen; bill more 
flattened anteriorly, longer and slenderer, not wider near end than 
at base; length of exposed culmen 8 times the greatest width of 
bill; tip of maxilla not at all or very slightly hooked; nail of bill 
MAGROWs ANG watheparallel-SIM@Si. 22. cea ster sc ilo-s.e 06 ood o Aristonetta. 
b*. Base of culmen not deeply concave; anterior outline of feathering at 
base of culmen not acutely pointed, but broadly convex ; feathering 
on sides of maxilla reaching anteriorly as far as that at base of 
culmen; bill less flattened anteriorly, shorter and stouter, decid- 
edly wider near end than at base; length of exposed culmen only 
21/2 times the greatest width of bill; tip of maxilla strongly 
hooked ; nail of bill rather wide and subtriangular....Perissonetta. 
@. Length of exposed culmen decidedly shorter than inner toe with claw. 
Dames SCzOl CulmMen deeply, CONCAVE. ..c6. cas 6 6 ote snes ace since -AVUNYIO. 
0. Base of culmen not deeply concave. 
ce. Tip of bill squarish, its width at posterior end of nail not less than 
Pee Same O The City WAI. Seeaiclerersieioiets bales Scecec coke e's Fulix. 
ce. Tip of bill much rounded, its width at posterior end of nail less 
than 21/2 times the length. of nail. 
@. Length of wing less than 5 times the length of exposed culmen : 
NOMLONSMPOIMLCOMOCEIP LLANE CLEStin ners ocksis oie + Sere chee elec ost Vyroca. 
@. Length of wing not less than 5 times the length of exposed 
culmen; a long (75 mm.) pointed occipital crest...... Fuligula. 
