■SUBFAMILY ANATIN^. 



275 



KEY TO THE GENERA. 



{For North American Species.) 



I. 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'. Lamella 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. 

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

 narrower at tip than at base. 

 a'". Lamellae of maxilla prominent. 

 Central tail feathers not elongated. 

 b'" . Lamellae 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. 



b"" . Central tail feathers not elon- 

 gated. Neck short. 



a*. Upper wing coverts blue or 

 bluish gray. 



b*. Upper wing coverts brownish 

 or slaty gray. 



b. Bill spatulate. 



TREE DUCKS. 



Dendrocygna. 



RUDDY SHEL- 

 DRAKE. 



Casarca. 



MALLARDS. 



Anas. 



GADWALL. 



Chaulelasmus. 



WIDGEON. 



Mareca. 



SPRIGTAU,. 



Dafila. 



liLUE-WlNGED 

 TEALS. 



Querquedula. 



GREEN-WINGED 

 TEALS. 



Nettion. 



SHOVELER. 



Spatula. 



