THE WHITE TERN 237 



Genus Gygis. 



Tail graduated. Bill stout at the base, pointed. Toes slender, 

 the middle one very long; the webs indented. Inter-tropical seas. 



The White Tern. 



Gygis Candida. 



Pure white, with a narrow black rim round the eyes. Bill black. 

 Legs and feet brown. Eye blue. Length of the wing, 9.5 inches; of the 

 tarsus, 0.6 inch. The eggs are pale cream or buff, with scrolls, lines, and 

 specks thickly spread over the egg; length, 1.6 inch; only one is contained 

 in a nest. Kermadec Islands. Widely distributed. 



Family Laridac. 



Bill with the upper mandible longer, and bent down over the 

 tip of the inferior one. Tail usually square at the end. 



Genus Lariis. 



Tail square, or nearly so. Bill more than twice as long as it is 

 deep. The nostrils linear. Hind toe well developed. Nearly 

 cosmopolitan, except Polynesia. 



The distribution of Larus is very peculiar, as it is not found 

 in the jNIalay Archipelago, New Guinea, or the whole of Polynesia ; 

 so that the gulls of Australia and New Caledonia are isolated 

 from their fellows. Our little mackerel gull, L. scopuUnus, and 

 the Australian L. novae-JiolIandiae, are allied to L. hartlaubi, of 

 South Africa and Madagascar; and this again is connected with 

 L. gelastes, which extends from the JMediterranean to the mouth 

 of the Indus. It is therefore probable that the ancestors of our 

 birds came from South Africa. Whether L. scopuUnus is 

 descended form L. novae-hollandiae, or vice versa, or whether 

 both are branches from L. hartlanJji, there is no evidence to 

 determine. 



Our black-backed gull, L. doniinicauus, is found in South 

 Africa, as well as in South America and Kerguelen Island, but 

 not in Tasmania or Australia. It is related to L. marinus, of the 



