302 NATATORES. 



operation is somewhat laborious. Sometimes the bird avails 

 itself of natural holes ; at other times it excavates a chamber 

 for incubation with its powerful bill. Though the great auk 

 does not come on land except for the purpose of breeding, it 

 does not leave the remoter parts of our seas in the winter ; 

 it is, indeed, so much in the water at all times that it is not 

 often seen. 



The female of this and other sea-birds which deposit their 

 eggs in holes rather than on the exposed ledges, are not 

 understood to sit so closely during the incubation, as those 

 which have the eggs exposed, but to resort occasionally to 

 the water, for the purpose of feeding themselves, instead of 

 being fed altogether by the males. The food of this species 

 is understood to be the smaller fishes, which the size, form, 

 and power of its bill enable it to capture by wholesale. 



THE PUFFIN (Fratercula). 



There is but one British species of puffin, the coulter-neb 

 puffin (Fratercula arctica), of which the following figure is 

 a representation in the summer plumage. 



The length is about twelve, the breadth twenty-one inches, 

 and the weight twelve ounces ; the colours of the plumage 

 are nearly the same as in the figure, the black being pecu- 

 liarly bright and glossy in the summer, and the only tint, 

 except black and white, being dusky brown on the quills. 

 The naked parts are, however, more varied in their colours. 

 The base of the bill and a portion of the cheeks are covered 

 by a coloured membrane. The bill gradually compressed in 

 its whole length, but with arched outlines to both mandibles, 

 the upper one hooked at the tip, and projecting a little 

 beyond the under. A membranous ring or ridge, yellowish 

 white, and perforated with small punctures, surrounds the 

 base of the bill. Beyond that the basal half of the bill is 

 bluish black and smooth, the half towards the tip yellowish 



