368 NATATOKES. 



digestion of their load of food, spread out their wings to 

 dry. 



The birds build high, and lay two rough-shelled eggs. In 

 winter the colour on the back fades, the white feathers on 

 the cheeks disappear, and the green crest is nearly obliterated. 

 The young have the throat ash coloured, and a tinge of brown- 

 ish ash upon all the upper plumage. 



The crested shag of authors, is merely this bird in its 

 breeding plumage. 



THE GANNET, OR SOLAN GOOSE (Sula lassana). 



A figure of the gannet in its mature plumage is given on 

 the frontispiece of this volume, with one more distant and 

 on an oblique descent, for the downward rush of the bird no 

 pencil can delineate. The bird is about three feet long, of 

 which the bill, including the naked skin at the base, occupies 

 about half a foot. The nostrils are obscure and nearly closed. 

 The expanse of the wings is at least six feet, and the weight 

 of the bird between six and seven pounds. Excepting the 

 tinge of buff on the crown, and the black primaries and the 

 bastard wings, the whole plumage of the mature bird is white. 

 The young are brownish black the first year ; have a white 

 spot at the end of each feather above, and a dusky spot cross- 

 ing the shaft of each, in the second year. In the progress of 

 these changes of the plumage, the irides change from brown 

 to yellow. 



In summer they betake themselves in immense multitudes 

 to particular cliffs, and especially to rocky islets at a small 

 distance from the land. The geology of rock-building birds, 

 though a curious subject, has not been much alluded to ; but 

 the gannets appear to prefer those of the trap formation to 

 any others, probably because the inequalities of these are 

 more flat and tubular than the schistose and granitic rocks. 

 It may, in some instances, appear that the birds are capri- 



