128 SNAKES OF CEYLON. 



Macropisthodon plitmbicolor Cantor.* 



(Latin " plumbum " lead, " color " colour.) 



The Green Keelbach. 



Sinhalese : " Pala polonga " (herb snake) (Fletcher). 

 Tamil : " Pacha naga " (green cobra). 



Synonymy. — Tropidonotus plumbicolor, Xenodon viridis, 

 Trigonocephalies ellioti, Amphiesma brachyurum, Halys ellioti. 



History. — First described by Cantor in 1839. 



General Characters. — A small snake, about 2 J feet in length. 

 Head subovate. Snout short, with a rounded canthus, and 

 broadly -rounded extremity. Eye moderately large, iris 

 greenish-gold, especially evident at its pupillary margin, and 

 the pupil round. Nostril round, rather large, occupying the 

 upper two-thirds of the suture between the nasals. Neck 

 fairly evident. Body rather stout, cylindrical, thickest 

 about the middle, from which it attenuates anteriorly and 

 posteriorly. Belly rounded. Tail short, about one-seventh 

 to one -ninth the total length. 



Identificaton. — The following syndrome will distinguish 

 it from all other Ceylon snakes. Costals in midbody 21 to 

 27, anal divided, and supralabials seven. 



Colouration. — Adults are a uniform grass-green dorsally, 

 with a few irregularly-disposed black spots anteriorly, which 

 have a tendency to form transverse bars, and a few scattered 

 small whitish spots. The head is grass-green above , merging 

 to white on the upper lip. A black streak passes from the 

 eye to the gape. The chin, throat, and belly are uniform 

 white or buff, or the belly may be greenish or plumbeous to 

 blackish. 



Young specimens are so different from adults that many do 

 not recognize them. They have a well-defined black chevron 

 on the nape, with the angle pointed forwards. Behind 

 this is a broad gorget of bright yellow or orange (dirty whitish 

 in spirit specimens), bordered posteriorly with black. 



* The specimen submitted to Cantor must have been an old one 

 preserved in poor spirit to have acquired a colour so different from 

 that observed in life, and so inappropriate a name. 



