SUBFAMILY A MATING. 



275 



KEY TO THE GENERA. 



{For North American Species.) 



/.Hind toe not lobed. 



A. Lower part of tarsus in front, without \ 

 transverse scutellae. Neck and legs long. [ 



B. Lower part of tarsus in front with trans- 

 verse scutellae. 



a. Bill not spatulate. 



a'. Lamellae of mandible projecting out- 

 ward. 



b'. Lamellae of mandible not projecting 

 outward. 



a" . Bill, depth at base less than width; } 

 broader toward tip than at base. f 



b". Bill, depth at base equal to width; 

 narrower at tip than at base. 

 a'". Lamellae of maxilla prominent. } 

 Central tail feathers not elongated. S 

 b'" . Lamellas of maxilla moderate. \ 

 Central tail feathers moderately > 

 elongated. ) 



c" . Bill, depth at base greater than 

 width. Sides of maxilla nearly 

 parallel. 



a'" . Central tail feathers much elon- ( 

 gated. Neck very long. j 



b"". Central tail feathers not elon- 

 gated. Neck short. 



a*. Upper wing coverts blue or f 

 bluish gray. ^ 



/;■*. Upper wing coverts brownish ( 

 or slaty gray. \ 



b. Bill spatulate. [ 



TREE DUCKS. 



Dendrocygna. 



RUDDY SHEL- 

 DRAKE. 



Casarca. 



MALLARDS. 



Anas. 



GADWALL. 



C halt lei as7nus. 



WIDGEON. 



Mareca. 



SPRIGTAIL. 



Dafila. 



lU.UE-WINGED 

 TEALS. 



(2uerqi(ediila. 



CJUEEN-WINGED 

 TEALS. 



Nettion. 



SHOVELEK. 



Spatula. 



