[Tim; I\ i;vs. | 



96 



KEY No. 9.— CLASSIFICATION ACCORDINO TO 

 *SLMILAKLTY OK DISSLMILAIUTY OF THE SEXES. 

 /. Si'Xe-! niikfi., or nenriy ultke. 

 Spotbill. 

 Gradwall. 

 Marbled Duck. 

 //. Sexe-i disiiuil If. 

 The rest. 



*NoTE.— Tl>e Diving Ducks sliow, however, rather lef 8 difference 

 between the isexes than mo-t snrface-feedeis do. 



