1 6 Journal of the F.M.S. Museums. [Vol. X, 



temporal shield is not so constant as in the other two forms, 

 in some examples having undergone fragmentation into 2, 

 3 or 4 pieces. It is noteworthy however, that this irre- 

 gularity is almost entirely confined to the individuals of one 

 locality. Of my 84 specimens, division of this shield on one 

 or both sides occurs in 16, of which 14 are from the mouth 

 of the Chantabun river. 



In 7 embryos extracted from their mother, a single 

 shield is present in 5, while in the remaining 2 it is divided 

 The mother has one shield on one side, two on the other. 



The supralabial shields are subject to the same irre- 

 gularity as in aagaardi. 



29 — 34, usually 31 — 33, scales round the neck, 35 — 42, 

 usually 37—39, round the body. Ventrals 271 — 343. 

 Average 300. (Chantabun, E. coast series, 296 ; Meklong, 

 W. coast series, 306). 



In the actual increase in the number of scale rows 

 round the body, as compared with that round the neck, this 

 form differs from both the preceding ones. In siamensis 

 the body count is from 5 — 9, usually 6 — 8, more than the 

 neck, whereas in the other two it is from 6 — 11, usually 

 8—10. 



Colour. — As in aagaardi, except that the yellow upon 

 the head is inclined to be more diffuse. In a few examples 

 it is in excess of the ground colour. Most of the specimens 

 are completely banded. Two individuals, Nos. 1279, 1298, 

 have the head and back almost entirely uniform darkish 

 grey ; other examples are characterized by a broad irregular 

 ventral band, either broken or continuous. 



Distribution. — From Meklong on the Western side 

 of the Gulf to Koh Chang on the East. It is particularly 

 abundant at the mouths of the Meklong and Chantabun 

 rivers. 



Dimensions.— Xs will be seen from a study of the 

 annexed tables, the two forms in the Gulf appear to grow 

 to a larger size than that found in the typical locality. 



Specimens of this snake which I sent to the Museum 

 of the Bombay Natural History Society, have been diagnosed 

 by Col. Wall as Hydrophis cyanocinctus. My reasons for 

 dissenting from his opinion have already been given in the 

 Journal of that Society (l.c.s.), and his reply to my criti- 

 cisms later (p. 864) do not in any way influence my previous 

 conclusions. 



The tables of FI. t. siamensis and H. cyanocinctus 

 which I have given here should be sufficient to shew that 

 the variation in the number of scale rows in these two forms 

 is not the same. Nor can his other remarks Avith regard to 

 scalation, size and colouration, in view of the large series 

 now available for examination, be maintained. As I iiave 

 already remarked, the two snakes when compared side by 

 side — however much they may be alike on paper— are to me 

 so different, that 1 am surprised that Col. Wall should ever 

 have thought them identical. 



