TROPIDONOTUS 



165 



5. Tropidonotus viperinus, Latreille 

 The Viperine Water-Snake 



Form. — Moderately slender ; head shorter than 

 in the preceding species ; snout obtuse, not pro- 

 minent ; eyes and nostrils directed upwards and 

 outwards, the former rather small, the latter some- 

 what valvular ; tail four to six times in the total 

 length. 



Head-Shields. — Rostral broader than deep, visible 

 from above. Nasal usually semi-divided. Inter- 

 nasals as long as 

 broad or longer, 

 su bt r iangular, 

 truncate in front, 

 as long as the pre- 

 frontals. Frontal 

 usually broader 

 than the supra- 

 ocular, once and 

 a half to twice 

 as long as broad, as long as or slightly longer 

 than its distance from the end of the snout, shorter 

 than the parietals, not in contact with the preocular. 

 Loreal as deep as or a little deeper than long. One 

 or two preoculars and two (rarely three) postoculars. 

 Temporals 1 + 2 or 1 + 3. Upper labials seven (rarely 

 eight), third and fourth (or third, fourth, or fourth 

 and fifth) entering the eye. Four (rarely five) lower 



Fig. 18 (after Sordelli) 



