30 Journal of the F.M.S. Museums. [Vol. X, 



When the anatomy of the Hydrophids comes to be 

 better known, a considerable regrouping of many of the 

 species will surely be necessary. T. annandalei should then, 

 I think, be placed by itself ; until this is done it may as 

 well remain where it is. 



The variation in my series is as follows : — Nasal shields 

 usually divided, either longitudinally or transversely, into 

 4, 6, or 8 pieces ; praefrontals usually divided into 3, 4 or 5 

 pieces ; frontal and supraoculars entire ; parietals separated 

 from each other, and sometimes from the frontal, by small 

 scales ; supralabials irregularly divided, sometimes entire ; 

 anterior chin-shields well developed in 1 example (No. 

 3888) , absent in all the others. 



62 to 73 scales round the neck, 74 to 91 round the body, 

 ventrals 320 to 368. 



Dentition. — Posterior maxillary, 6 ; palatine, 8 ; ptery- 

 goid, 20 ; mandibular, 16 (1 specimen examined). 



The type locality of this snake is Patani, and the 

 specimens from there are said to have from 90 to 100 scales 

 round the body. As will be seen by the annexed table, 

 none of my series has so large a number. 



Enhydrina valakadyn (Boie). 



Enhydrina valakadien, Bouleng., Cat. Sn. B. M., p. 302 (1896) ; 

 idem. Fauna Malay Pen., Rept. and Batr., p. 193 (1912). 



Enhydrina valakadyn, Stejneyer, Herpet. Japan, p. 437 (1907) ; 

 Wall, Mem. Asiat. Soc. Bengal, II (8), p. 191 (1909) ; N. de Rooij, 

 Rept. Ind. Aust. Archipel., II, p. 221 (1917) ; idem, J. Bombay 

 N. H. S., XXVI, p. 803 (1919). 



Enhydrina valakadyn is one of the most widely dis- 

 tributed, and without doubt the most common, of all the 

 sea snakes. It has also been accorded a greater range of 

 variation in the number of its scale rows (40 to 60 round 

 the neck, 50 to 70 round the body) , than any other known 

 species. 



This is true, but only when the species is considered 

 as a whole, and without regard to the region whence the 

 individuals have come. The very large series that I have 

 been able to examine from the Malayan region shews that 

 the variation in any one locality is considerably less — about 

 12 to 14 — or, if the sexes are considered apart, seldom more 

 than ten. The number of specimens that I have seen from 

 the Indian coasts is not great, but in so far as they go they 

 agree entirely with the Malayan examples in this respect. 



I gather also from these Indian specimens, that the 

 maximum average number of scale rows obtains in that 

 region ; and I find too that in the disposition of certain head 

 shields they differ from the Malayan form. 



Tentatively, therefore, I recognize two forms, wliich 

 are as follows : — 



An Indian form. 

 Forma valakadyn (type locality, Tranquebar). 45 to 

 60 scales round the neck, 55 to 70 round the body ; ventrals, 



