86 MANUAL OF PHILIPPINE BIRDS. 



Family LARIDiE. 



Characters same as those given for the Order. 



Subfamilies. 



«'. Tail more or less forked (except in Anoiis) ; bill slender; terminal portion 

 of culmen straight or bnt slightly curved; angle of lower mandible not 

 prominent Sterninae (p. 86) 



a". Tail even; bill stouter; terminal portion of culmen decidedly curved; angle 

 of lower mandible distinct Larinae (p. 95) 



Subfamily STERN I N^. 



TliG members of this subfamily afford no very tangible characters to 

 distinguish them from the gulls other than those already mentioned. 

 However, the terns are, as a rule, of more slender form and more airy 

 and graceful flight. The wings, bill, and tail are proportionately longer 

 and the body smaller than these parts in the gulls. 



Genera. 

 a\ Tail more or less forked. 



b^. Tail but little more than one-third of wing, its outer feathers broad and 



rounded Hydrochelidon (p. 86) 



b". Tail much more than one-third of wing, its outer feathers narrow and pointed. 



Sterna (p. 88) 

 a". Tail graduated; plumage sooty brown Anous (p. 94) 



Genus HYDROCHELIDON" Boie, 1822. 



Bill short and slender; legs and feet small; webs between the toes 

 deeply emarginate; wings long, when closed, exceeding the tail; tail 

 short, nearly square. 



Species. 



o\ Black or dark gray below (adults in summer). 



V. Upper tail-coverts and tail white; under wing-coverts black. 



leucoptera (p. 86) 

 6^ Upper tail-coverts and tail gray; under wing-coverts white., hybrida (p. 87) 

 a^ White below (adults in winter and young). 



6*. Tail white leucoptera (p. 86) 



b^. Tail gray. 



c\ Rump gray like back hybrida (p. 87) 



c'. Rump white (young) leucoptera (p. 86) 



76. HYDROCHELIDON LEUCOPTERA (Mei.sner and Schinz.) 



WHITE-WINGED BLACK TERN. 



Sterna leucoptera Meisner and Sciiinz, Vog. Schweiz (1815), 264. 



Hydrochelidon leucoptera Saunders, Cat Birds Brit. Mus. (1896), 25, 6; 

 Sharpe, Hand-List (1899), 1, 133; Oate.s, Cat. Birds' Eggs (1901), 

 1, 174; McGregor and Worcester, Hand-List (1906), 20. 



Mindanao (Steere Exp., Bourns <£- Worcester). Central and southern Europe 

 to central Asia and China; Australia, New Zealand, Africa in winter. 



