300 NATATORES. 



confusion in the descriptions; a confusion which is easily 

 avoided by a little attention to the different plumages. 



In summer, the bill, which is two inches in the gape, has 

 five furrows in the upper mandible, and two in the lower, is 

 black, with a white band across the middle. The feet and 

 claws are black ; the irides chestnut brown ; and the gape 

 orange. The head (except a narrow white stripe in front of 

 the eyes), the hinder part of the neck, and the scapulars, are 

 black ; the throat and front of the neck brownish ; and all 

 the rest of the under parts, and also the tips of the secondary 

 quills, white. In the winter plumage, the throat, fore part 

 and sides of the neck, fade to white, and the black on the 

 upper part becomes dull and brownish. In both these plu- 

 mages the males and the females very nearly resemble each 

 other ; but the young birds differ from both. In them the 

 bill is much shorter and narrower than in the mature birds, 

 and without the furrows and the white band. The chin and 

 part of the throat are also mottled with white; and the 

 white stripe in front of the eyes is not so well defined. 

 Those characters gradually alter, however, and the young 

 bird may be traced through all the gradations, especially 

 those of the bill, which are the most remarkable, up to the 

 perfect character of maturity. 



THE GREAT AUK (Alca impennis). 



This is a much larger species, and inhabits much farther to 

 the north than the former. It is the Penguin, or wingless 

 bird of the northern hemisphere, and does not approach any 

 of the British shores, excepting the most northerly and 

 remote ones, and these only for a month or six weeks in tho 

 heat of summer. It appears early in May, and disappears 

 again about the middle of June, and while it is on the coast 

 of St. Kilda and other remote and lonely places it is but 

 seldom seen. 



