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



clearly defined black bands. Head entirely black, or with 

 a yellow spot behind each nostril, or with the horse-shoe 

 mark ; with age the bands become less distinct but are 

 always clearly recognizable. 



Dentition. — Posterior maxillary, 5 or 6 ; palatine, 7 ; 

 pterygoid, 9 or 10 ; mandibular, 13 or 14 (4 specimens 

 examined) . 



Variation. — The frontal shield is very variable as 

 regards size, but except in one example is always shorter 

 than its distance from the rostral ; in one example only it is 

 nearly as small as in the type. One example has the 4th 

 supralabial touching the eye on one side, and the 3rd, 

 4th and 5th on the other. Fragmentation of the upper 

 labials, and cuneiform scales among the lower are rare, 

 the former condition occurs in two examples, the latter in 

 one. 



//. klossi with its uniform rows of imbricate scales, 

 appears to be closely allied to H. nigrocinctus Daudin, from 

 the Indian seas, and H. melanoceplialus Gray from the 

 Riu Kiu Islands. In the number of scales round the body 

 these three forms are much alike, but klossi has more 

 ventrals, a smaller frontal and fewer supralabials. 

 Nigrocinctus also has two anterior temporals. 



As will be seen by inspection of the accompanying 

 tables, the Siamese form has a slightly higher average 

 number of scale rows than the Malaccan form. The varia- 

 tion is as follows : — 



Straits of Malacca, forma typica. 



23 — 25 scales round the neck ; 31 — 35 round the body. 

 Ventrals, 361—386 (av. 372). 



Gulf of Siam. 



23 — 27 scales round the neck ; 33 — 39 round the body. 

 Ventrals, 360—386 (av. 372) . 



Breeding. — In the Gulf this occurs in March, from 2 

 to 5 young being produced. Females taken off" the coast 

 of Perak in September, shewed the embryos well advanced 

 in development. 



Hydrophis consobrinus Smith. 

 Journ. Nat. Hist. Soc. Siam, II, p. 341 (1917). 



Diagnosis. — Posterior maxillary teeth, 5. Head very 

 small, body very long and slender anteriorly ; 25 to 31 scales 

 round the neck, 36 to 45 round the body ; ventrals, 328 to 

 401. A single anterior temporal. Head Avith a curved 

 yellow mark above. 



Description. — Head very small, body very long and 

 slender anteriorly, its greatest depth in the adult being from 

 two and a half to three times that of the neck. Eye 

 slightly greater than its distance from the mouth ; rostral 

 broader than deep, visible above ; frontal once and one 

 third to once and a half times longer than broad, as long 

 as or slightly shorter tlian its distance to the rostral ; one 



