search of food such as lizards, frogs, small mammals, and birds. This sluggish pit viper is usually encountered on low shrubs during morning hours, but it mostly occupies in grasslands and rain forests. In mornings, it is seen to stay on top of trees to obtain sun rays to heat its body. It uses its tail to hold on to a tree branch. This is not a particularly defensive species, but if agitated, it will vibrate its tail tip, form a sinuous loop with the fore body, and lash and attempt to bite, seldom with a hissing sound. It produces live young mostly during June and July. Venom The venom is primarily haemotoxic, with victims experiencing severe pain and swelling of the bitten area, oedema and blisters, and localised tissue necrosis; the pain of the wound may last for a few days. Ptosis and lymphadenopathy takes place. Also in some victims, polyuric renal failure and cardiac electrophysiological dysfunction occur, but fatalities have not been reported. References Further reading Pulihansu Book of Snakes, 2009. Donndorff, Johann August. 1798. Amphibiologische und Ichthyologische Beyträge zur XIII. Ausgabe des Linneischen Natursystems. Dritter Band. Amphibien und Fische. Weidmannschen Buchhandlung. Leipzig. vi + 980 pp. (Coluber trigonocephalus, p. 203.) Sonnini, C.N., and Latreille, P.A. 1801. Histoire Naturelle des Reptiles, avec figures dessinées d'après nature; Tome III. Seconde Partie. Serpens. Crapelet. Paris. 335 pp. (Vipera trigonocephala, pp. 332–333.) trigonocephalus Snakes of Asia Reptiles of Sri Lanka Endemic fauna of Sri Lanka Reptiles described in 1798