176 



NOTE ON A RARE SEA SNAKE (TtrALASSOPniS AN031ALVS) 

 FROM THE COAST OF SIAM. 



By Malcolm. A. Smith, m. r. c. s., l. r. c. p. 

 With a plate. 



Thalai^sophis (nwmalus, Schmidt, Aliliandl. Nat. Hamb., 

 II, p. 81, pi. iv (1852) ; Boalena;, Cat. Sn., HI, p. 269 

 (180G). Wall, Monograph Sea-Snakes, p 244 (1909). 

 Hi/flinph/s annmala, Giinthei', Rept. Brit. Iiid., p. 379 

 (1864) ; Jan, leon. Gen. 40, pi. iv, fig. 1. (1872). 



The occurrence of this snake off the coast of Siam is of con- 

 siderable interest. Hitherto it has been known only from the islands 

 of the Malayan Archipelago (Java, Sumatra, Borneo and the Moluccas) 

 from whence some nine specimens have been obtained, all of which are 

 distributed in the Continental Museums. 



At the end of March this year, I obtained two specimens at the 

 mouth of the Chantabun river, S. E. Siam; and later on, through an 

 old diver living there, procured eight more. All of them were caught 

 in the fishing baskets just within the mouth of the river. 



M.V first two specimens agreed entirely, except in colouration, 

 with Schmidt's description of this species, but an examination of a 

 of a larger number showed small differences, as might have been ex- 

 pected. I have therefore given a de.scription of mine in full, drawn 

 lip from the ten specimens. 



Poison fangs, followed after a small interval, by 5 smaller teeth 

 graduall}' diminishing in size, all of which show the pre.sence of grooves. 



Bodily configuration, moderately stout. Eye equal to or slightly 

 less than its distance from the mouth. Rostral broken up into 4 or 5 

 pieces. Internasals narrow, elongate, equal to or shorter than the 

 praefrontals. Frontal small, variable as regards length and breadth, 

 sometimes partially or completely divided. Nostril large, lying 

 entirely within the posterior of the two nasal shields. 1 prae- and 1 

 or 2 post-oculars. Temporals small, 2 + 3 or 3 + 3. Upper labials 7 

 to 0, usually the third, fourth and fifth entering the eye ; horizontal 

 division of the third and (or) fifth sometimes present ; prae-frontal 

 usually touches the second. Four lower labials in contact with the 



JOURN. NAT. HIST. SOC. SUM- 



