THE BIRDS OF SOUTH-WEST AND PENINSULAR SIAM- 51 



and to S. longipennis Nordtn., a somewhat closely related species 

 breeding in North China, Kamschatka, etc., and wintering in the 

 south. All the birds found in these waters are, however, either 

 immature or in winter phimage, and it is impossible to identify them 

 with any great certainty. 



The balance of probability is in favour of their belonging to 

 the Asiatic race, which breeds in Tibet, etc., and winters in the south. 

 The bird has not been, found on the East Coast of Siam. 

 53. Sterna dougalli Mont. 



Sterna dougalli, Mont., Orn. Diet. Suppl. 1813. fig. (no pagination- 

 Scotland); A., p. 492 (Laynah Creek); H., p 142 (Koh Pennan) ; 

 Williamson, Journ. Nat. Hist. Soc. Siam, ii, 1916, p. 63 (Koh 

 Rin and Koh Phai, Inner Gnlf of Siam). 



The Roseate Tern has been much divided and many names 

 are available for eastern and southern races, but we do not here 

 attempt precisely to assign the Siamese specimens to any subspecies. 



Two birds obtained by ourselves on Koh Pennan on 26th 

 May, 1913, in freshly moulted full breeding plumage, have the tarsi 

 and toes orange-red, the claws blackish, and the bills entirely black 

 with no trace of red whatever. Wing 6 , 228 : S , 213 mm. 



On the other hand, three males from Pulau Jemor, Aroa Ids., 

 Straits of Malacca, shot on 2nd. August, 1906, also in full breeding 

 plumage, have the tarsi, toes and claws orange-red, and the bills also 

 orange-red with no trace whatever of black. Wing d", 214, 217, 

 230 mm. 



54. Sterna sumatrana sumatrana Raffles. 



Sterna sumatrana, Raffles, Trans. Linn. Soc. xiii, 1821, p. 329 

 (immature — Sumatra) ; A., p. 493 (Tenasserim). 



Sterna melanauchen, Temminck, PI. Col. 1827 (Coast of Celebes) ; 

 H., pp. 18, 142 (Koh Pennan, Bandon Bight); Williamson, 

 Joiuni. Nat. Hist. Soc. Siam, ii, 1916, p. 63 (Inner Gulf of 

 Siam). 



This beaultiful tern, which in life has a delicate rosy flush 



over the under surface like in S. dougalli, is a species frequenting 



rocky islands and keeping as a rule well out to sea. It is common 



I. Gyldenstolpe, Kungl. Sv. Vet. Akad. Handl. M. Baker, Joia-n. N. H. Soc. Siam, iii, 1919. 



56, No. 2, 1916. (first part). 



J. Robinson, Journ. F. M. S. Mus. vii, 1917. Baker, Journ. N. H. Soe. Siam, iii, 1919. 



K- Kloss, Ibis, 1918. (second part). 



L. Eobinson and Kloss, Journ. N. H. Soc. Siam, M. I. Baker, Journ. N. H. Soe. Siam, iv, 1920. 



iii, 1919. (tliird part). 



VOL. V, NO. 1, 1921. 



