299 



among the outermost holms and islets, and also far down in the 

 fjords. 



With this species, the plumage does not appear to be regu- 

 lated by age or sex. 



Birds of both sexes shot in June and July the last two sum- 

 mers, display the following diversity of coloration: — 

 Male. Under plumage white, and also nape. 



— Entirely black. 

 Female. Under plumage white, nape grey. 



— Under plumage somewhat lighter than back, nape whit- 

 ish-grey. 



— Under plumage white. 



— Entirely black. 



— Under plumage white. 



In some pairs the plumage of both sexes is alike, in others 

 it is different. Individuals vary no less in size, which in the 

 females, for instance, ranges from 479 to 525, the length of 

 the elongated rectrices in the same birds also varying from 177 

 to 220 mm. 



An uncommon variety of this species, procured at Varanger, 

 was transmitted to the University Museum by Nordvi. The plu- 

 mage of this individual (a male) is a dark browny black, the 

 tips of the secondaries and of the upper wing-coverts only being 

 white. 



On most of the numberless islets scattered along the coast, 

 wherever a colony of gulls, Somateria, and a few Grallæ have 

 congregated to breed, some pairs of this species will be generally 

 observed. They are also found breeding on rocky promontaries 

 of the mainland. The eggs are deposited on the top, or at the 

 side, of an isolated knoll, in a level spot, where the heather is 

 short; sometimes, though rarely, in more humid localities among 

 cloud-berry plants. During the period of incubation the birds takes 

 up their post in the neighbourhood of the nest on some elevated 

 mound. If you approach, the old birds do not readily leave the 

 spot, but keep alighting on and flying off the surrounding knolls, 



i 



