14 
ON THE LESSER GUILLEMOT 
The bill is said to be longer in the Foolish Guillemot, 
and there is an indenture near the point in both mandibles, 
while, in the Lesser, there are only the rudiments of a 
slight indentation in the lower mandible. My experience 
proves that the bill of the Foolish Guillemot is shorter in 
the young, and gradually lengthens with age. This was 
the case with those I reared from a few days old till they 
were ready to fly, when they had acquired precisely the 
plumage of the Lesser Guillemot ; but were still inferior 
even to it in size and length of bill. The less numerous 
indentures in the bills, which are regarded by Montagu 
as peculiarly supporting his opinion, seem to me to lead to 
an opposite one. It is well known (as he himself admits) 
that the Razor-Bill , so analogous to the Foolish Guillemot 
in its changes of plumage and habits, has in its young state 
neither the size of bill, nor the numerous indentations, 
which it has in the adult. 
It is surprising that this analogy should not have excited 
his suspicion. The white line extending from the bill to 
the eye in the Razor-Bill, and from the eye down the neck 
in the Foolish Guillemot, are conceived to be distinctive. 
In many specimens I examined, during last summer, these 
marks were absent ; and in many specimens of the other 
two birds I have found them well defined ; and the Danish 
writer Mohr *, in his Islandik Natur Historie, expressly 
mentions this as no ground of distinction. 
• In this author I find most of the opinions I entertained on northern 
sea-fowl fully confirmed. For instance, he distinctly states the Colymbus 
Immer to be the young of the Northern Diver ; and mentions not only its 
capability, but vigour of flight, — a fact which, being so long unaccountably 
overlooked, gave rise to so many fanciful and ridiculous conjectures to ac- 
count for its habits and incubation. It is singular that this book, which is 
one of the best topographical works in natural history, seems so little 
known. It was published at Copenhagen in the year 1786. 
