728 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



central pair not so long. About one-fourth of tibia bare. Rest of 

 structure as Sabine's but bill considerably smaller. 



Soft parts. — Bill (ad.) black, (juv.) brownish at base ; gape 

 and orbital ring (ad.) vermilion ; legs and feet (ad.) orange-red, 

 (juv.) flesh -brown ; iris brown. 



Characters. — No subspecies. Wedge-shaped tail and small bill 

 distinguish species. 



Breeding-habits. — Nests usually in colonies on little low-lying 

 island in swampy tundra, frequently in company with Arctic Terns. 

 Nest. — Built of dry grasses and Carex ; sometimes with a few 

 leaves of Betula or Salix, or even moss, till it reaches about 5 to 8 

 in. above wet surface of bog. Eggs. — Normally 3, but sometimes 

 2 only : not unlike those of Sabine's Gull : ground-colour greenish- 

 olive, sparingly blotched with umber-brown. Average of 36 eggs 

 (Buturlin), 43.3x31.6. Max. : 45.8x32.1 and 44.5x32.9. Min. : 

 38.6x31 and 43x30 mm. Breeding-season. — Early June in 

 Kolyma delta. Incubation. — Partly at any rate by female. No 

 information as to period. Single brooded. 



Pood. — On breeding ground apparently insectivorous. Buturlin 

 records coleoptera, diptera (gnats), and other insects. A bird shot 

 by Nansen threw up two shrimps. 



Distribution. — England. — One near Tadcaster (Yorks.), Dec. 22, 

 1846, or Feb. 1847 (W. Milner, Zool. y 1847, p. 1694, and cf. p. 1784 ; 

 Saunders, p. 659 ; Birds Yorks., p. 665). 



Distribution. — Abroad. — Breeds in delta of Kolyma River and 

 at mouth of Indigirka and Alaseja in north-east Siberia and doubt- 

 less other places on arctic shores of Asia and probably of America. 

 Has been found in many places in arctic seas and casual visitors 

 have been obtained in Fseroes, Heligoland, Norway (once), France, 

 and near Sardinia. 



Genus LARUS L. 



Labus Linnseus, Syst. Nat., ed. x, i, p. 136 (1758 — Type by subsequent 

 designation of Selby, Cat. Generic and Subg. Types, p. 48, 1840, L. marinus L.). 



Gulls of various sizes, bill strong, laterally compressed, upper 

 with tip pointed and bent down over lower. Nostrils longitudinal, 

 beginning near base. Tarsus as long as middle toe with claw or 

 (mostly) longer, in front with scutes, otherwise reticulate, hind toe 

 well developed. Wings long and pointed, first developed primary 

 longest. Tail short, square. Sexes alike in colour, female generally 

 smaller. Winter -plumage generally different on head and neck 

 only, juvenile essentially different. About 44 species in all 

 countries. 



