EGGS OF BRITISH BIRDS. 99 



Northern India ; and Prjevalsky found it nesting in the valley of 

 the Hoang-ho in South-east Mongolia. Canon Tristram found it 

 breeding in Algeria, in nests of the Eared Grebe which the young 

 had left ; but in India, Anderson saw it building floating nests of 

 its own, some of which were more than a foot in diameter and 

 four inches high. 



The eggs of the Whiskered Tern are readily distinguished from 

 those of the Black and White-winged Black Terns by their larger 

 size, smaller markings, and paler and greener ground-colour. The 

 eggs vary in length from 165 to 1*4 inch, and in breadth from 

 116 to 105 inch. 



THE GULL-BILLED TERN. 

 (Sterna anglica.)* 



Plate 31, Figs. 6, 8. 



About half-a-dozen specimens have been obtained in Great 

 Britain. The species nests in the temperate and sub -tropical 

 portions of both hemispheres. The nests which I found in the 

 salt-islands off the coast of Asia Minor were not very close to 

 each other, but they were all in one part of the island. The 

 eggs were on the sand, never on the black mud ; some were lying 

 in slight natural hollows between the patches of vegetation on the 

 bare sand, without any attempt at a nest, but generally a slight 

 hollow was scratched in the earth or sand, and a few bits of sea- 

 weed or dead grass frequently formed an apology for a nest. 



The most common number of eggs in each nest was two ; three 

 were not uncommon, but I never found four in one clutch. The 

 eggs of the Gull-billed Tern vary in ground-colour from bumsh- 

 white to huffish-brown, with occasionally a very slight tinge of 

 olive. The spots are never very large, rarely as big as a pea ; the 

 surface-markings are brown, and the underlying ones, which are 

 always very conspicuous, are grey. Occasionally the spots are 

 most numerous round the larger end of the egg, but they are 

 generally evenly and sparingly distributed over the whole surface. 

 The eggs vary in length from 21 to 1"8 inch, and in breadth 

 from 15 to 1*3 inch. Small eggs of the Sandwich Tern might 

 sometimes be mistaken for eggs of the Gull-billed Tern ; but the 

 latter are almost always much duller in colour. 



* Gelochelidon anglica — Saunders, Cat. B., Brit. Mus., XXV., p. 25. 



