560 SNAKES OF CBYBON. 



Pterygoid : edentulous for about half its length posteriorly ; 

 teeth scaphiodont, and number 5 to 20. Mandibular : 

 teeth scaphiodont, and number 10 to 16. 



Distribution, — South-east Asia, Central and South America. 

 Of the forty species described, eleven are included in the 

 Indian fauna, and one of these occurs in Ceylon, viz., iri- 

 gonocephalus . 



Tbimebesurus tbigonogephalus (Daudin). 



(Greek " trigonon " a triangle, and " cephale " the head.) 

 The Geylon Pit-viper. 



Sinhalese: "pala polonga " (Ferguson). Tamil: "pachi 

 virian " (green viper), and " kopi virian " (coffee viper) 

 (Abercromby). 



Synonymy. — Coluber capite-triangulatus, Vipera trigono- 

 cephala, Cophias trigonocephalus, C. nigromarginatus, Trigono- 

 cephalus nigromarginatus, Megsera trigonocephala, M. olivacea. 

 Bothrops nigromarginatus, Trimeresurus trigonocephaly's. 



History. — First referred to by Lacepede in 1789, who also 

 figured it. It received its specific title from Daudin in 1803. 



General Characters. — Head flattened, broad, and roughly 

 pear-shaped ; broadest about midway between the eye and the 

 neck. Snout short, with pronounced canthus, not declivous, 

 broadly rounded terminally. Eye moderate in size, with 

 golden iris, and vertical pupil. Neck very much constricted. 

 Body moderately elongate, cylindrical, and robust. Belly 

 rounded. Tail prehensile and rather short, being about 

 one-sixth the total length. 



Identification. — It is the only Ceylon snake with a loreal pit, 

 and the whole crown covered with small scales. If the head 

 is broken it will be known by its scale rows counting 19 two 

 heads-lengths behind the head, 19 at midbody, and 15 two 

 heads -lengths before the vent, and the vertebrals not being 

 enlarged . 



Colouration, — ^Dorsally it is green of various shades, variously 

 mottled, and variegated with black. The markings in many 

 specimens are disposed so as to form more or less distinct cross- 

 bars. In others a series of round twin-sjDots pass down each 



