OF THE BEITISH ISLANDS. 411 



Genus COSMONETTA, or Harlequin Ducks. 



Type, COSMONETTA HISTEIONICA. 



Cosmonetta, of Kaup (1829). The Harlequin Ducks are distinguished 

 by having the primaries uniform brown. The head is uncrested ; the bill is 

 conical, the base of the upper mandible overlapping the tomium, and the base of 

 lower mandible for some distance being covered with a soft naked membrane. 

 The peculiar colour-pattern of the plumage is another generic distinction of con- 

 siderable importance. 



But one species of Harlequin Duck is known, and as this is a rare abnormal 

 migrant to the British Islands its distribution, habits and characteristics will be 

 fully described in the following chapter. 



