NON-INDIGENOUS BRITISH BIRDS. 167 



sitter, and when leaving the nest voluntarily covers the 

 eggs v/ith down, a proceeding common to most if not 

 all species in this order. 



Range of egg colouration and measurement : 

 The eggs of the Red-crested Pochard are from seven to 

 ten in number. Specimens taken by Mr. Salvin in Algeria 

 are described as of "a most brilliant fresh green colour 

 when unblown ; the contents were no sooner expelled, 

 and the q^^ dry, than the delicate tints were gone, and 

 their beauty sadly diminished." After being in collections 

 for any length of time they may be described as grayish- 

 olive. Average measurement, 2'3 inches in length by 

 1*6 inch in breadth. Incubation is performed by the 

 female, but the duration of the period is unknown. 



Diagnostic characters : Unfortunately the down 

 of this Duck does not appear to have been described, 

 and we are left without' a valuable clue to the correct 

 identification of its eggs. They very closely resemble 

 those of the Pochard, but always appear to be greener, 

 approaching in colour those of the Golden Eye, but the 

 down of the latter species is pale. 



Family ANATID.^. Genus Fuligula. 



Sub-family FULIGULIN^. 



WHITE-EYED POCHARD. 



Fuligula nyroca iyGilldenstddt). 



(British : Rare abnormal spring, autumn, and winter migrant.) 



Single Brooded. Laying season, end of April to June, 

 according to latitude. 



Breeding area : Southern PaLnearctic region and 

 extreme North-western Oriental region. The White- 



