192 British Birds ^ 



and sometimes in the same specimen. — Fig. %, plate 

 XII, 



GREAT BLACK-BACKED G^JUu—^Larus 

 marinics). 



Black-back, Cob, Great Black-and-white Gull. — By 

 no means a numerous species, and not affecting society 

 as so many of the other Gulls do. It breeds, in some 

 cases, on the ^larsh or Salting-spaces met with so 

 abundantly on some of the southern and eastern 

 shores ; but more commonly on rocky parts of the 

 coast. Thus, it breeds very abundantly on the Orkney 

 and Shetland Islands. The nest is made of a large 

 quantity of dry grass simply thrown together. The 

 eggs are three in number, often bearing a great 

 resemblance to those of the two species last named, 

 but usually distinguishable by the larger masses of 

 surface colouring, and by some superiority in size. 

 The Black-back's eggs are much esteemed as articles 

 of food, or for cooking purposes generally. The yolk 

 is very deep and rich-coloured, and the white colour- 

 less or transparent. Each female will lay three sets 

 of eggs ; the first two sets being, in some cases, 

 customarily taken, and the last left for her to hatch. 



GLAUCOUS G\JJIL—{Lar7is glaucus). 



Large White-winged Gull, Burgomaster. — A Gull 

 equally large with the last (one of which, shot by 

 myself, exceeded six feet from the tip of one wing to 

 that of the other); but one of merely casual occurrence 

 as a British bird. 



