AND BLACK-BILLEB AUK. 
15 
The sulcae in the bill of the Alca Torda cannot be con- 
sidered as peculiar, for Montagu mentions a specimen of 
Black-billed Auk shot in February, in which the bill was 
as much furrowed as in the Razor Bill ; and Fabriciu^ 
also says, that all the young Alcse have the bill less sulca- 
ted and coloured than the adults ; — hinc character de 
sulcis sumptus lubricus satis.*" 
This I have myself repeatedly verified. It may be stri« 
kingly seen in what occurs in the Puffin : and indeed it 
seems surprising that its young should not also have been 
described as a distinct species, equally as the young Razor- 
Bill. 
The black in the plumage of the Razor-Bill and Foolish 
Guillemot is less deep, and it extends over the whole head 
and neck ; while, in the others, the throat and sides of the 
head are white, and the black parts of the plumage are of 
a deeper tint. This, which is stated as peculiar to the 
Lesser Guillemot and Black-billed Auk, is exactly the 
winter-plumage of the young of the others. The old one& 
also assume the same appearance, still retaining the slight 
difference of a fainter shade of black on the upper part of 
the body. The specimen of young Guillemot, caught by 
Montagu in June, exhibits distinctly the young of the 
preceding autumn, passing into the plumage of the adult ; 
and the winter-plumage of the Razor-Bill, as stated by 
Fabricius, is the same as that of the Black-billed Auk, 
The Little Auk is admitted to change its plumage in win- 
ter, to become white on the throat and sides of the head,— 
while these parts are black in summer. This is exactly such 
a change as its congenerous bird the Razor-Bill is asserted 
to undergo. 
If the Colymbus Troile and Alca Torda be distinct spe- 
cies from the others, and preserve their distinct appearance^ 
how happens it that we never meet with them in winter ? 
