288 THE NESTS AND EGGS OF 



markings are large, and both numerous and well- 

 defineJ. Average measurement, 275 inches in lengtii, 

 by I '8 inch in breadth. The duration of the period of 

 incubation is unknown, as is also which sex performs 

 the duty. 



Diagnostic characters : The eggs of the Iceland 

 Gull cannot always be distinguished from those of the 

 Lesser Black -backed Gull and the Herring Gull, but as a 

 rule they are not nearly so blotched as those of the former 

 species, nor ever so dark in ground colour as those of 

 the latter. The locality of the eggs should settle their 

 identity at once, as the breeding areas of these two 

 species do not impinge upon that of the Iceland Gull. 



Family LARID^. Genus Larus. 



Sub-Family LARINM. 



GLAUCOUS GULL. 



Larus glaucus, Fabricins. 



(British : Irregular nomadic winter migrant.) 



Single Brooded. Laying season, June. 



Breeding area : Northern Nearctic and Pal^arctic 

 regions. The Glaucous Gull breeds in Iceland, Spitz- 

 bergen, Nova Zembla, at Vardo in North-eastern Norway, 

 and along the shores of the Arctic Ocean across Europe, 

 Asia, and America to Greenland, where it ranges as far 

 north as lat. 82°. 



Breeding habits : The Glaucous Gull is a nomadic 

 migrant, wandering little from the vicinity of its breeding 

 area during winter, and retiring north as soon as the 



