1920.] Dr. Malcolm Smith : Sea Snakes. 19 



Variation. — The frontal in 15 examples is as long as 

 its distance from the rostral ; in one it is longer than its 

 distance ; in no examples are the chin shields absent ; 

 in two instances the posterior pair are in contact with 

 each other ; the parietal shield fails to touch the postocular 

 in two examples only on both sides, and in one example 

 more on one side. Average ventral count, 291. 



Dentition. — H. caerulescena has an unusually large 

 number of teeth in the maxillary bone behind the poison 

 fangs. I find the dentition as follows : — Posterior maxil- 

 lary, 13 to 16 ; palatine, 7 or 8 ; pterygoid, 21 to 23 ; 

 mandibular, 21 to 25 (7 specimens examined) . 



Hydrophis klossi Boulenger. 



Hiidrophis klossi, Boulenger, Fauna Malay Pen., Rept. and 

 Batr,,p. 190 (1912) ; Smith, Journ. Bombay N. H. S., xxiii, p. 787 

 (1915). 



35 exs., Straits of Malacca, 13 $ , 5 9 ; Gulf of Siam, 

 10 $,7 9. 



Boulenger's description was drawn up from a single 

 specimen, but with the large amount of material now 

 available this can be considerably augmented, and it will 

 be simpler to redescribe the species than to add a number 

 of points to his original remarks. 



Description. — Head small, body long and slender 

 anteriorly, the posterior depth in the adult being from 2^/^ 

 to 3 times that of the neck. Snout distinctly projecting 

 beyond the lower jaw ; eye equal to or slightly less than 

 its distance from the mouth. Rostral as broad as deep, or 

 broader than deep, the portion visible above equal to from 

 1|3 to 213 the internasal suture ; frontal small, longer than 

 broad, usually shorter than its distance from the rostral ; 

 one prae- and one postocular ; one large anterior temporal ; 

 usually five supralabials, 3rd and 4th touching the eye, 

 sometimes a small sixth ; two pairs of cliin-shields, subequal 

 in size, the posterior pair partly or completely separated ; 

 four infralabials in contact with the chin-shields. 



23 to 27 scales round the neck, 31 to 39 round the body, 

 imbricate throughout, the anterior ones elongate with 

 bluntly pointed extremities, smooth or faintly keeled, the 

 posterior ones broader with more rounded extremities and 

 more strongly keeled. Ventrals distinct throughout, 360 to 

 402. 



Greyish or greenish above, yellowish or whitish below, 

 with from 50 to 75 dark bands. In the fore part of the 

 body these are as broad above as below and slightly broader 

 than their interspaces, behind usually twice as broad above 

 as below. In some the bands are incomplete ventrally, 

 and in some they are linked up by a black line running along 

 the ventral shields ; or the lower part of the neck may be 

 entirely black. Head blackish to olivaceous, lighter on the 

 snout, sometimes with an indistinct horse-shoe shaped 

 mark, its front across the praefrontals and the ends upon 

 the temporal shields. The young at birth are white, with 



