1920.] Dr. Malcolm Smith : Sea Snakes. 13 



available for examination, I find that they intergrade so 

 completely with each other, that it seems impossible to 

 distinguish between them. The three forms are : — 



HyDUOPHIS TORQUATLS TORQUATl S. 



33 — 37 scales round the neck ; 43 — 49 round the body. 



Ventrals 242—306. 

 Head in the adult pale grey, with a considerable 

 suffusion of yellow on the top. 



Habitat. Coast of Perak and Selangor. 



Hydrophls torquatus aagaardl 



32 — 37 scales round the neck ; 39 — 47 round the body. 

 Ventrals 276—325. 



Head in the adult dark olive to blackish, with a curved 

 yellow mark across the snout and along the sides. 



Habitat. Coast of Patani, Gulf of Siam. 



Hydrophls torquatus siamensis. 



29 — 35 scales round the neck ; 35 — 42 round the body. 

 Ventrals 271—343. 



Colouration as in aagaardi. 



Habitat. Inner Gulf of Siam. 



Hydrophis torquatus torquatus. 



Hydrophis torquatus, Giiatlier, Rept. Brit. Ind., p. 369, pi. XXV, 

 fig. H, (1864) ; Boulenger, Fauna Malay Pen., Rept. and Batr., p. 

 190 (1912) ; N. de Rooij, Rept. Ind. Aust. Archipel., II, p. 231 (1917). 



Distira torquata, Wall (part.), Mem. Asiat. Soc. Bengal, II, (8), 

 p. 229 (1909). 



Coast of Perak, 39 exs. ; Bernam River, Selangor, 2 exs. 



Gunther's types came from Penang, so that my Perak 

 coast specimens are, for all practical purposes, topotypes. 

 On the whole they are a very uniform lot, and shew more 

 constancy in scalation than the other two forms found in 

 the Gulf. 



Variation. — The frontal shield, except in one instance, 

 is always shorter than its distance to the rostral. The 

 supralabials normally are seven, the first four being usually 

 complete, the fifth divided, and the last two (rarely are 

 there three), very small. Chin-shields well developed, the 



Eosterior pair in contact with each other or partly separated 

 y a scale. Four infralabials in contact with the chin- 

 shields ; cuneiform scales invariably present between the 

 infralabials, usually a series after the second. 



33 — 37 scales round the neck, 43 — 49 round the body, 

 those anterior elongate, with truncate or bluntly pointed 

 apex, those posterior more or less hexagonal, imbricate or 

 subimbricate throughout, with a central tubercle or short 

 keel. Ventrals distinct throughout, 242 — 306. Average 277. 

 The number next to 242 is 260. 



In adult specimens the depth of the body posteriorly 

 is from 2 to 2% times that of the neck. 



