COMMON SHELDRAKE. 227 



brittle, smooth, and with considerable polish. Average 

 measurement, 27 inches in length, by 1*9 inch in breadth. 

 Incubation, performed by both sexes, the female sitting 

 the most, lasts about a month. 



DIAGNOSTIC CHARACTERS : The eggs of this and 

 most other species of Ducks are readily and safely 

 identified by the down of the parent bird, which forms 

 a lining to the nest. It is most important, therefore, 

 that the collector should take at least a portion of the 

 down and a few of the small feathers from every nest, a 

 proceeding which will tend to authenticate his specimens, 

 and immensely increase the interest and value of his 

 collection. The down of the Sheldrake is lavender-gray, 

 mixed with a few almost white tufts. Armed with the 

 down, the eggs of the present species cannot be confused 

 by the collector with those of any other Duck breeding 

 in our islands. 



Family ANATID^E. Genus ANAS. 



Sub-family ANATIN&. 



G A D W A L L. 



ANAS STREPERA, Linncetts. 

 Single Brooded. Laying season, May. 



BRITISH BREEDING AREA: The Gadwall is only 

 known to breed in one portion of our islands, in the 

 county of Norfolk. Originally only a pair of pinioned 

 birds that had been taken in Dersingham Decoy, and 

 turned loose on the lake at Narford, upwards of forty 

 years ago, were known to breed ; but since that time 

 their descendants have continued to do so, as well as to 



