THE BIRDS OF SOUTH-WEST AND PENINSULAR SIAM. 



47 



LARIDAE 



Gulls and Terns. 



/Bill much compressed, knife-like 

 I Bill iioimal 



I Upper mandible longer than the lower 

 t Mandibles of equal length 



[Plumage dark above and below : outermost tail feather 



\ not the longest 



(plumage not dark below : outermost tail feather the longest 



Bhynchops (extra limital). 

 . . Larus hruneicephalus. 



Anous stoliclus. 

 Geloclielidon anglica. 

 Hydroprogne caspia. 



{ Tarsus long, exceeding middle toe and claw 

 1 Tarsus short, less than middle toe and claw 



(Bill very stout, tail less than 1/3 the wing . . 

 I Bill normal, tail 1/2 the wing or more 



(Tail almost square, the feathers rounded ,. 

 I Tail forked, the feathers pointed 



[Larger, bill blood-red in breeding plumage : tail grey in 



J non-breeding plumage .. •• Hydrochelidon hybrida 



' 1 Smaller, bill dull red in breeding plumage : tail white in 

 i non-breeding plumage 



„ (Tail long, exceeding 3/4 the wing 

 JTail shorter, less than 2/3 the wing 



q ( Mantle and back sooty brown 

 \ Mantle and back grey 



(Large, wing over 11.5 inches 

 10- Medium, wing not more than 11 inches 

 ( Small, wing less than 8 inches 



,, I Larger, bill greenish 



12 



\ Smaller, bill orange or yellow 



(Whole crown always white 

 I Crown black or partially black 



K. leucoptera. 

 Seeiia seena. 



Sterna anaetheta. 



S. bergii pelecanokles. 

 S. media. 



S. sumatrana. 



10 



12 

 15 

 11 



13 



14 



, „ ( Feet blackish . . . . 



^"^ [Feet reddish 



(Inner webs of primaries edged with white to the tips : 

 ^ . J bill red : feet brighter 



1 1nner webs of primaries not edged with white to the tips : 

 \ bill black : feet duller 



( Shafts of all primaries white 

 15 - Shafts of two outer primaries brown 

 I Shafts of three outer primaries brown 



Note. In this Order ive have not, as a rule, attempted to attach rigorously correct 

 subspecific names to the various forms. This is almost impossible tvitho^ot com- 

 parative material from all parts of the Oriental and Australasian regions, lohich 

 is not in our possession. 



S. longipennis. 



. . S. dougalli. 

 S. fluviatilis tibetana. 



. . S. sviensis. 



. . S. minuta. 



S. saundersi. 



I. Gyldenstolpe, Kungl. Sv. Vet. Akad. Handl. M. 



56, No. 2, 1916. 

 J. Robinson, Journ. F. M. S. Mus. vii, 1917 

 K. Kloss, Ibis, 1918. ^ , 



L. Bobinson and Kloss, Journ. N. H. Soe. Siam, IWI. 



iii, 1919. 



Baker, Journ. N. H. See. Siam, iii, 1919. 



(first tart). 

 Baker. Journ N.H. Soc. Siam, iii, 1919. 



(second part). 

 . Baker, Journ. N.H. Soc. Siam, iv, 1920. 



(third Pi»ft), 



VOL. V, NO. 1, 1921, 



