DUCKER—DULWILLY 171 
white, though as long as their reproductive power lasts they 
“breed true.” The amount of variation in domestic Ducks, how- 
ever, is not comparable to that found among Pigeons, no doubt 
from the absence of the competition which Pigeon-fanciers have so 
long exercised. One of the most curious effects of domestication in 
the Duck, however, is, that whereas the wild Mallard is not only 
strictly monogamous, but, as Waterton believed, a most faithful 
husband—remaining paired for life, the civilized Drake is notori- 
ously polygamous. 
Very nearly allied to the common Wild Duck are a consider- 
able number of species found in various parts of the world in 
which there is little difference of plumage between the sexes—both 
being of a dusky hue—such as Anas obscura of North America, 4. 
superciliosa of Australia, A. pewcilorhyncha of India, A. melleri of 
Madagascar, 4. zanthorhyncha of South Africa, and some others. 
It would be impossible here to enter upon the other genera of 
Anatine. We must content ourselves by saying that both in 
Europe and in North America there are the groups represented 
by the SHOVELER, GARGANEY, GADWALL, TEAL, PINTAIL, and 
WicEoN—each of which, according to some systematists, is the 
type of a distinct genus. Then there is the group 4x with its 
beautiful representatives the Wood-Duck (42. sponsa) in America 
and the Mandarin-Duck (4. galericulata) in Eastern Asia. Besides 
there are the SHELD-DRAKES (Zadorna), confined to the Old World,! 
and remarkably developed in the Australian Region ; the Musk- 
Duck (Cairina) of South America, which is often domesticated, and 
FEX SPONSA. DENDROCYGNA. 
(After Swainson.) 
in that condition will produce fertile hybrids with the common 
Duck ; and finally the Tree-Ducks (Dendrocyyna), which are almost 
limited to the Tropics. 
DUCKER, see DoucKEr. 
DULWILLY, said to be a local name of the Ringed PLOVER, 
Aigialitis hiaticola; and, according to Prof. Skeat, signifying dull 
of will or stupid, though the application of such a name is not 
obvious. (See, however, DOTTEREL.) 
1 To these belong apparently the genera Chenalopex and Plectropterus, though 
from their size the species of each bears in English the name of Goosr, 
