198 Descriptions oftivo new species of Reptiles. [No. 3, 



lateral, and ovoid scales, of which the three most anterior and central- 

 ones are the largest and most conspicuous ; the first central scale of 

 the nape of the neck, which fits in at the posterior angle of the 

 junction of the two occipitals, is pentagonal, end the largest. In 

 reality, the occipital plates do not cover the whole of the back of the 

 occiput proper, or do not reach to the nape ; so that, the first dorsal 

 (or rather cervical) scales are, in fact, situated on the occiput : and 

 hence the head of this snake looks as if only the anterior half of its 

 upper surface, were covered with plates, and the posterior half with 

 scales. This is a strongly marked peculiarity which at once serves 

 to distinguish this snake. 



Nasal orifices narrow- shaped and curved, partially covered with a 

 valve (capable of being closed over the orifice, when the snake is 

 under water), the nasal slit being situated, in part, between two 

 plates, i. e. the pras-nasal, and post-nasal ; the prte-nasal plates (one 

 on each side) being large, situated straight in front of the anterior- 

 front als, and are shaped somewhat like an uneven disc of which a 

 portion, posteriorly, has been cut out, leaving a sort of receding angle 

 in the posterior margin of the plate. And each pras-nasal plate is 

 also cleft posteriorly, from near its centre, by the nasal slit, 

 thence making a short curve backwards to the line which separates the 

 prse-nasals from the post -nasals. The latter are situated rather laterally, 

 being small and oblong shaped. The rostral plate is pentagonal, shaped 

 like a triangle rising from a parallelogramic base of equal breadth 

 with the base of the triangle, and the apex of the triangle extends 

 nearly half way back between the two pra3-nasals. Upper labials, on 

 right side 6, on left side 5 ; the third labial entering the orbit. 

 The most posterior upper labial plates (the 6th labial plate on one 

 side, the 5th on the other) very large. Posterior to the proper lateral 

 upper labial plates on each side there is a largish sub-temporal plate 

 placed above two small plates. Temporal plates, proper 4, small. 

 Post-ocular plates 2, situated one above the other. Ante-ocular 1, 

 curved, long transversely. Loreal 1, smaller, of an irregular shaped, 

 quadrilateral figure. Median lower labials 2, very small, and situated 

 one behind the other. Lateral lower labials 6, on each side, the two 

 anterior lateral lower labials, on each side of the median lower labials, 

 very long. Chin shields 2, very large. 



