GULLS, TERNS, AND SKUAS. 



685 



morth Asia to Kashmir and Himalayas, east to Ussuri and Japan. 

 Northern birds are migrants, wintering in Mediterranean countries 

 south to Atlas mountains and Egypt ; in south Persia, India to 

 -Ceylon, China and south Japan. Casual Faeroes, Spitsbergen, 

 Greenland and eastern U.S.A. (from Newfoundland) to Virginia. 

 Represented by a very distinct subspecies on Amami, Loo Choo or 

 Riu Kiu Is., south Japan. 



Order LA HI (Lariformes). 



Comprises Gulls, Terns, and Skuas ; latter rather different 

 from other two groups and entitled to subfamily rank, some- 

 times even raised to a family, Stercorariidce. Distinction of Terns 

 and Gulls as families or subfamilies not considered necessary. 

 Palate schizognathous, nasals slit-like, schizorhinal (less typical in 

 Stercorariince). Basipterygoid processes absent. Cervical vertebrae 

 15, sternum strongly keeled. Oil-gland present and tufted. 

 Plumage rich and soft, after shafts present, 10 developed primaries, 

 wings aquintocubital. Rectrices 12. Wings long and pointed, 

 flight wonderfully light and sustained. Middle toe longer than 

 outer, three front toes connected by webs, therefore good swimmers. 

 Plumage of adults also with rich down, young covered with thick 

 and soft down, nidifugous. 



Family LARIME. 



Characters of Order Lari. 



Key to genera of Order Lari. 



f Tail square 2 



1 ■{ Middle rectrices longer than lateral ... 4 



[Tail forked 5 



~ /Hind toe developed, with claw .... 3 



\JSTo hind toe, only a small knob without claw . . Rissa 



J Lower part of tibia bare Larus 



\ Tibia entirely feathered Pagophila 



f Feet rough with very sharp claws, horny covering of 



upper bill divided into two pieces by sharp, narrow 



. j groove, thus basal portion looking like a cere, tip of 



] bill strongly hooked Stercorarius 



! Feet more smooth, claws blunt, horny covering of 

 [_ upper bill not divided, tip of bill not strongly hooked Ehodostethia 

 _ /Claws blunt, gonys much less than half bill . . . Xema 



\ Claws pointed, gonys about half bill ... 6 

 f Tail more than half length of wing, lateral rectrices with 



very long, narrow tips (" streamers ") . . . Sterna 



6 -J. Tail less than half length of wing, lateral rectrices 

 longer than others, but not with very long, narrow 



[_ tips (" streamers ") 7 



- /Bill slenderer, height at base much less than 10 mm. . Chlidonias 



\ Bill stouter, height at base 10 mm. or much more 8 

 f Six middle rectrices about equal, bill longer than head, 



e J over 50 mm Hydroprogne 



j Six middle rectrices gradually longer, bill not longer 



(_ than head, under 50 mm Gelochelidon 



