SUBFAMILY ANATINM. 



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. 

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

 narrower at tip than at base. 

 a'". Lamellas 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. J 



b"". Central tail feathers not elon- 

 gated. Neck short. 



a 4 . 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. 



Afareca. 



SPRIGTAIL. 



Dafila. 



1U.UE-WINGED 

 TEALS. 



Querquednla. 



GREEN-WINGED 

 TEALS. 



Nettion. 



SHOVELER. 



Spatula. 



