1920.] Dr. Malcolm Smith : Sea Snakes. 17 



Breeding. — ^Young are born in February and March. 

 Two females are of interest, as shewing the diflference in 

 the size of the embryos due to nutrition. Tlie parents are 

 of equal length 925 mm. — but while one contained a brood 

 of 8, the other had only 3. Both broods 'are apparently 

 fully developed. The average length of the family of 8 

 is 285 mm., that of the other 325. 



To this race I refer the specimen recorded by Flower 

 from the Gulf of Siam (P.Z.S., 1899, p. 687, No. 190) 

 as Hijdvophis ohscarus (now diadema) . I count it to 

 have 32 and 38 scale rows, with 302 ventrals and 10 

 posterior maxillary teeth. It is I believe the only record of 

 diadema from the Gulf. 



Hydrophis caerulescens (Shaw). 



Hydrophis caerulescens, Bouleng., Cat. Sn. B. M., p. 275 (1896) ; 

 idem, Fauna Malay Pen., Kept, and Batr., p. 187 (1912) ; Wall, 

 Journ. N. H. S. Bombay, xxiii, pp. 373/374 (1914). 



Distira caerulescens, Wall, Mem. Asiat. Soc. Bengal, ii, (8), 

 p. 231 (1909). 



This snake has a wide distribution, and from Bombay 

 to C.ochin China appears to be found almost everywhere 

 along the Asiatic coast. Curiously enough it has not yet 

 been recorded from the Malay Archipelago, 



With its large number of strongly keeled scales round 

 the neck and body, it is well differentiated from most othervS, 

 and has not been subject to much confusion in the past. 



Boulenger's conception of this species, as regards the 

 number of scales round the neck and body, is without doubt 

 too restricted. Wall, working on more material, found the 

 variation to be considerably greater. He was dealing 

 however, chiefly with Indian specimens. With the large 

 series before me now (98 examples), from the coasts of 

 Siam and the Malay Peninsula, the range can be still further 

 increased. Between the most extreme forms, such as one 

 from Orissa (No. 14493, Indian Museum), with 43 scales 

 round the neck, and 51 round the body, and another of 

 mine (No. 1352) from the Gulf of Siam, with 31 round the 

 neck and 38 round the body, the difference is so great that 

 they might be considered distinct, were it not that the 

 gradation between them can be easily traced. 



I have only been able to examine a small series from the 

 Indian coasts, and between them and examples from the 

 Straits of Malacca I can find no marked difference. Those 

 from the Indian coasts have a slightly higher average num- 

 ber of scale rows, and a larger series might shew this 

 character to be constant, the maximum average number 

 of scale rows obtaining in that region. W^all also has 

 pointed out that this sea snake possesses a character which 

 is almost pecuHarly its own, namely, that the parietal shield 

 nearly always fails to touch the postocular. His observa- 

 tion, derived chiefly from Indian specimens, applies equally 

 well to my series from the Straits of Malacca^ 



As shewn later, this character is absent in H. caerulescens 

 thai. I have found it present also, as an abnormality, in 

 H. klossi and H. consobrinus. 



