48 MESSRS. ROBINSON AND KLOSS ON 



45. Larus brunneicephalus Jerd. 



Larus brunneicephalus, Jerdon, Madras Journ. L. S. xii, 1840, p. 25 



(Madras); A, p. 491 (south to Tongka); ]., p. 148 (Inner Gulf of 



Siam) ; Williamson, Journ. Nat. Hist. Soc. Si;iru, iii, 1918, p. 36 



(Inner Gulf of Siam). 



On the western side of Peninsular Siam only doubtfully 



recorded as a rare straggler as far south as Junk Seylon in winter. 



Apparently common in winter on the eastern side in the Inner Gulf 



of Siam and as far south as Koh Lak. Quite unknown from Malayan 



waters. 



46. Hydrochelidon hybrida (Pall.). 



Sternn hyhridu, Pall., Zoojir. Ros?o-Asiat. ii, p. 338 (1811, Volga), 

 Ilydrochelidon hyhrid i, Williamson, Journ. Nat, Hist. Soc. Siam, 



i, 1914, p. 48 (Bangkok); I., p. 147 (1916); Williamson, op, 



cit. iii, 1918, p. 37 (Bangkok). 



The occurrence of the Whiskered Tern in the area rests for 

 the present on Gyldenstolpe's bird from Koh Lak, shot in December, 

 and therefore probably in winter plumage. This bird had a wing of 

 220 mm,, which, though large for H. leucoptera, is small for H. 

 hyhrida, so that the identification yet remains to be fully confirmed^ 

 The species is, liowever, abundant in the vicinity of Bangkok, and in 

 east and central Siam, whence we have examined many specimens, 

 both in breeding and .winter plumage, in the collection of Mr. W. 

 J. F, Williamson, 



47. Hydrochelidon leucoptera (Meisn, & Schinz), 



Sternt leucojMra, Meisner & Schinz, Vog. Schweiz, 1815, p. 264 



(Lake Geneva), 

 Ilydrochelidon leucoptem, Williamson, Journ. Nat. Hist. Soc. Siam, 



iii, 1918, p. 37 (nr. Bangkok). 



All specimens of this genus that we possess from the Straits 

 of Malacca, north to Penang and the Siamese boundary, are this 

 species which, in immature and winter f)lumage, can only be distin- 

 guished from the preceding by its smaller size, white tail and tail- 

 coverts, and markedly shorter bill. We have seen two specimens 

 from Bangkok in young and winter plumage, shot in April and 



A. Hunio & Davison, Stray l-calheis, vi, 1878. E. (). Grant, Fasciculi Malayenses, iii (Birds), 1905 



B. MiiUor, 1)10 Ornis ilcr Insel Salansa, 1882. F. Robinson and Kloss, Ibis, 1910-11. 



C. Oatcs, Bir^s Bnt. Itiinnah, Vols, i & ii, 1883. G. (iuiidncr, .Trturn. N. H. Soc. Siam, i, 1915. 

 O. Bonhoto. r. Z. S. 1901, Vol. i. H. Itobinson, Journ. l\ M. S. Museums, v, 1915, 



JOURN. NAT. HIST. SOC. SIAM. 



