44 



DUCKS, GEESE, AND SWANS 



Distribution. Tropical and subtropical seas, chiefly north of the equa- 

 tor ; north regularly to Florida, Texas, and California, and casually to 

 Wisconsin and Nova Scotia. 



Nest. Made of sticks, placed in the tops of bushes or low trees. 



Fig. 61. 



Fig. 62. 



ORDER ANSERES: LAMELLIROSTRAL 



SWIMMERS. 



FAMILY ANATIDJE: DUCKS, GEESE, AND SWANS. 



KEY TO GENERA. 



1. Tarsus shorter than middle toe without claw. 



2. Lower mandible without trace of lamellae along sides, 

 edges of mandibles strongly toothed or serrate. 



3. Tooth-like serrations of mandibles sharp and strongly 

 inclined backward .... Merganser, p. 45. 



3'. Tooth-like serrations of mandibles blunt and not dis- 

 tinctly inclined backward . Lophodytes, p. 47. 



2'. Lower mandible with a distinct series of lamellae along 

 side as well as cutting edge. 



3. Lower part of tarsus with small hexagonal plates and 

 no transverse scutelbe in front. 



Deiidrocygiia, p. 09. 

 3'. Lower part of tarsus with a row of transverse scutel- 



Ia3 across the front. 

 4. Tail without upper coverts, the base of the stiff 



feathers scarcely concealed. 

 5. Tail feathers 18 .... Erismatura, p. 04. 



5'. Tail feathers 20 Nomoiiyx, p. 65. 



4'. Tail with base well concealed by upper coverts. 

 5. Hind toe without a flattened membraneous lobe. 

 6. Bill long and much wider near end than to- 

 ward base Spatula, p. 54. 



6'. Bill not much wider near end than at base. 

 7. Tail feathers wide and rounded at, end. 



Aix, p. 55. 



7'. Tail feathers narrow and pointed at tips. 

 8. Tail graduated more than a third of its 



total length. 



9. Tail feathers 14 . . Mareca, p. 49. 

 9'. Tail feathers 1(5. 



10. Bill longer than middle toe without 



claw Dafila. p. 54. 



10'. Bill shorter than middle toe without 



claw . Chaulelasmus, p. 49. 



8'. Tail graduated less than a third of its 



total length. 



9. Wing more than 8 . . Alias, p. 47. 

 9'. Wing less than 8. 



