1920.] Dr. Malcolm Smith : Sea Snakes. 5 



types of all the species here described will be presented 

 to the British Museum of Natural History, together with a 

 selection from the type series. 



In the preparation of this paper I have, above all, to 

 thank Mr. G. A. Boulenger, F.R.S., for the generous help 

 by correspondence which he has so freely given me at all 

 times. 



I have to thank also Mr. H. C. Robinson, Director of 

 F.M.S. Museums, and Mr. C. Boden Kloss, for the valuable 

 collections made under their direction, and sent to me from 

 time to time. 



I am indebted also to Dr. Nelson Annandale of the 

 Indian Mjseum, to Messrs. N. B. Kinnear and W. S. Millard 

 of the Bombay Natural History Society, and Dr. Hanitsch 

 of the Rattles Museum. Singapore, for the loan of specimens 

 in their charge on various occasions. 



Mr. C. L. Groundwater I have to thank for his careful 

 drawings of the heads of snakes, and Mr. J. R. Bell for 

 the map. 



Hydrus platurus (Linn.). 



^ Boulenger, Cat. Sn. B. M., II, p. 267 (1896) ; idem, Fauna Malay 

 Pen., Kept, and Batr. p. 181 (1912) ; Stejneger, Herpet. Japan, p. 439 

 (1907) ; Wall, Mem. Asiat. Soc. Bengal, II (8), p. 248 (1909) ; idem, 

 Journ. Bombay N.H.S., XXVI, p. 808 (1919) ; Barbour, Mem. Mus. 

 Gomp. Zool. Harvard, XLIV, p. 129 (Nov. 1912) ; N. de Rooij, Rept. 

 Ind. Aust. Archipel., II, p. 224 (1917). 



Pelamudriis platurus, Stej., Proc. U. S. N. Mus., 38, p. Ill, 

 (May, 1910). 



Gulf of Siani, 20 exs. ; Straits of Malacca, 9 exs. 



This snake appears to be a strictly marine species. All 

 the specimens referred to above were taken in purely salt 

 water. The Gulf series was caught with a dip net while 

 lying on the surface of the water, and was taken one 

 morning while oH" the coast between Hua Hin and Koh Lak. 

 Altogether some 50 individuals were seen. With the 

 exception of a few si)ecimens of the common Enhydris 

 hardwickii, they were the only snakes noticed. Although 

 I spent the succeedhig week in cruising down the same 

 coast, going as far South as Lat. 9" (Bandon) for the 

 express purpose of collecting sea snakes, I did not meet 

 afterwards w^ith more than half a dozen snakes of any kind. 

 The weather conditions were the same throughout. 



Colouration. — (Gulf series). Black above, yellow to 

 dark brow^n on the sides and below, the two colours meeting 

 in a clear line of demarcation. Tail with black dorsal and 

 ventral bars ; sometimes with a few spots as well. Upper 

 lip the same colour as the sides of the body. 



Some of the darker examples have a yellow stripe 

 separating the black of the back from the brown of the 

 under parts. The amount of black upon the back 

 is variable in width, occupying from 11 to 18 scales, but 

 in no instance is it narrow enough to deserve the name of 

 vertebral band. All of this series belongs to Boulenger's 

 vars. D and E, and they are merely variations of the same 



