210 LAEID^.— LAEUS. 



Family LAEID:^. Gulls, Teens, and Skimmees. 



Bill without a cere. Hind toe generally present. Toes partially or fully 

 webbed. Claws moderately curved, not sharp. Breast-bone with two notches 

 on each side of posterior margin. Plumage grey and white or black and brown. 



The family Laridce may be divided into three classes, viz. — 



(i.) With three toes united as far as the claws. 



Rissa, the Kittiwake. Wings long. Eemiges thirty-one. Tail not wedge- 

 shaped. 



(ii.) With four toes {three united, one webbed to tarsus). 

 Pagophila, the Ivory Gull. Wings long. Bill decurved. 



(iii.) With four toes (three united as far as the daws, hind toe free). Bill neither 

 lamellate nor toothed, and without a nail. Fourth toe rudimentary. 



Larus. Tail square. 



Rhodostethea. Breast white and rose. Tail wedge-shaped. 



Hydroehelidon. Bill as long as head. Tail slightly forked. Legs short. Webs 

 incised. 



Sterna. Bill longer than head. Tail forked. < 



Anous. Whole body blackish brown. Tail graduated. 



Xema. Bill shorter than head. Tail forked. Legs long. 



Stercorarius. Bill strong, cutting, compressed, and with a cere. Eemiges 

 twenty-six or twenty-eight. Tail rounded. 



Subfamily Laein^. 



Bill stout, curved at tip, upper mandible longer than the lower. Nostrils 

 oblong, at some distance from base of mandible. Tarsus scutellated in front. 

 Anterior toes fully webbed. Hind toe small, free, and raised (webbed to tarsus 

 in LeucophcBus and Pagophila ; rudimentary or obsolete in Rissa). Tail square, 

 or nearly so (forked in Xema ; cuneate and mid pair produced in Rhodostethia). 



(i.) Tail square, or very nearly so. 

 Hind toe free. 



Genus LARUS. 

 X(£/)os=a ravenous sea-bird, in classical Greek. Akin to Old Norse Uri=a, Tern. 



Bill strong, and always more than twice and usually about three times as long 

 as it is deep. Wings long, exceeding tail. First primary longest. Some species in 

 summer have the head darker than the neck. — In winter; Head and neck are 

 white, or streaked with brown. For purposes of distinction these birds are here 

 given in three groups, viz. — 



A. Head with hood darker than neck in summer (227-231), 



B. Head without hood and tail white (232-235). 



C. Head without hood and tail with subterminal black band, 

 (Cosmopolitan with exception of Polynesia and the Central Pacific.) 



