LARIDA‘—GULLS. 203 
build, longer legs and proportionately longer wings, which latter 
extend considerably beyond the tips of the tail-feathers. 
Length 22 inches; culmen 2°5; wing 16 to 17; tail 7°6; 
tarsus 2°5. 
Young: Like adults, are mainly recognisable by their pro- 
portionally longer wings than in young of Z. glaucus. 
Distribution: Breeds in Alaska and within the Arctic Circle 
from Greenland to Behring Straits. Straggles southward in 
autumn and winter as far as the coast of France. 
Habitat: The sea-coast. 
Genus PAGOPHILA. 
IVORY): GULL. 
Pagophila eburnea (Piipps). 
Adult (Summer): Luxtire plumage pure white ; bill yellow, 
greenish-grey at base; /egs and feet d/ack ; irides dark brown. 
Length 16 to 18 inches; culmen 1°4; wing 13; tail 6; 
tarsus I°4. 
Young in first plumage: Are said to be of an almost 
uniform ash-grey. 
A young female before us, shot in January, has the base of 
the bill and upper throat clouded or mottled with greyish- 
black ; shoulders, scapulars and some of wing-coverts with 
terminal blackish spots ; longest primaries broadly tipped with 
white ; bill horn-coloured at base, whitish towards tip; other- 
wise white as in adult. 
Distribution: Inhabits the Circumpolar regions; of 
casual occurrence during autumn or winter south of the 
Arctic Circle. 
Habitat : The sea-coast, never penetrating far inland. 
Genus Rissa. 
KITTIWAKE. 
Rissa tridactyla (Lzun.). 
Adult (Summer): Back and wings s/ate-grey, secondaries 
