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



Co/our.— This varies considerably with age. The 

 young are whitish, with from 46 to 63 well defmed black 

 bands, which are often incomplete ventrally. Head black, 

 with a whitish or yellowish mark across the snout and along 

 the sides. Adults are pale grey above, yellowish white below, 

 with darker grey bands, less clearly defined, and usually 

 incomplete ventrally in the posterior part of the body. In 

 some aged individuals the bands have almost entirely dis- 

 appeared, leaving the back more or less uniform grey. 

 Head grey, with the yellow marks more extensive and less 

 defined, this latter colour sometimes covering the whole 

 of the top of the head except a small patch on the crown. 



Length. — One example measures 835 mm. in total 

 length, but the majority of the specimens are under 700 mm. 



Dentition. — Posterior maxillary, 8 to 10, palatine, 

 7 — 8 ; pterygoid, 19 to 22 ; mandibular, 16 — 18 (14 speci- 

 mens examined) . 



Wall, in his Monograph, has included under torquatus 

 another snake which Boulenger now recognises as diadema, 

 (the obscurus of the Catalogue, p. 284) . His argument for 

 combining these two species does not convince me, and the 

 points of difference upon which he states Boulenger has 

 separated them, do not appear to me to be the correct ones. 

 The difference in the number of scales round the neck and 

 body, and the marked difference in the number of ventrals, 

 have been overlooked by him entirely. 



That these two species cannot be identical is well shewn 

 by my series, which, as already stated, is topotypical. In 

 the number of scales round the neck and body, and in the 

 number of ventrals, they agree very closely with Giinther's 

 description. 



Hydrophis torquatus aagaardi, subsp. nov. 



Similar to H. t. torquatus, but with average fewer 

 number of scale rows round the body, greater average 

 number of ventrals, larger frontal, and darker colouration. 



Type. — Adult male, author's number, 1169, collected 

 July 1917, off the coast of Bangnara, Patani, Gulf of Siam, 

 by Mr. C. J. Aagaard. 



Number of specimens examined, 44, all from the type 

 locality. 



Variation. — The frontal shield in this form is very 

 variable both in size and shape. In 26 examples it is as 

 long as its distance to the rostral, in 7 examples it is shorter 

 than, and in 9 it is longer than, its distance from that shield. 

 In No. 1267 it is considerably shorter than its distance to the 

 rostral, in No. 1273 it is as long as its distance to the end 

 of the snout, yet there can be no doubt that these two 

 represent the same species. Two postoculars occur in one 

 example. As with the typical form, the temporal shield 

 is verj' constant, a single scale being present in every 

 instance. The supralabials however are more subject to 

 division in aagaardi, and fragmentation may occur in any 

 of them after the second. 



