Eye-colour, Comb, and Spurs 
fact recorded by Bonhote, on page 245 of the 
Proceedings of the Fourth International Ornitho- 
logical Congress, that in the case of ducks de- 
scended from crosses between the pintail, the 
mallard, and the spotbill, the drakes in full 
breeding plumage showed a mixture of pintail 
and mallard characteristics, while, in their non- 
breeding plumage, the colouring of the spotbill 
is predominant. 
An important point, and one which does not 
seem to have been pointed out by any zoologist, 
is that eye-colour, comb, and spurs in birds and 
horns in mammals do not stand in the same 
relation to the sexual organs as do the other 
external characteristics. For example, the cas- 
trated Nilgai (Boselaphus tragocamelus) acquires 
horns, but not the characteristic male colour. 
In the common Indian Francolin Partridge 
(Francolinus pondicerianius), the cock differs from 
the hen only in the possession of spurs. The 
same applies to the various species of Snow 
Cock (Tetrvaogallus). There is a breed of game- 
cocks which display plumage like that of the 
hen, but such birds have the comb and spurs 
developed as ‘in normally feathered cocks. 
The white eye of the white-eyed Pochard 
Drake (Vyvoca africana), and the yellow eye of 
the cock Golden Pheasant (Chrysolophus pictus), 
which are purely male characters, show them- 
selves earlier than the male plumage. Occasion- 
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