292 SNAKES OF CEYLON. 



except the next species. Tongue pale pinkish, with white tips. 

 Mouth pale pinkish inside. 



Identification. — The horizontal pupil will proclaim the 

 specimen one of the species of Dryophis. The appendage 

 at the point of the snout is only seen in two of these, viz., 

 mycterizans and pulverulentus. The former has always 

 lateral white stripes running along the belly, which are not 

 present in the latter. 



Colouration. — -Variety (a) typicus (Linn6) : The upper 

 parts of the head, body, and tail are bright verdant-gfeen, 

 and the surface of the scales dull. The beUy is of an equally 

 intense but lighter shade of green, and is adorned on each 

 side by a well-deiined, narrow, white (sometimes bluish) 

 stripe situated on the ventral shields. In ordinary circum- 

 stances the dorsal green is uniform, but under excitement, 

 owing to the separation of the scales, a very beautiful che- 

 quered ornamentation of black and white is revealed in the 

 anterior two-thirds of the body, which gives a very striking 

 appearance to the snake. Viewed closely, the black and 

 white ornamentation consists of squares arranged in echelon, 

 those of one side meeting those of the other at an angle 

 directed forwards. These hues are seen to be almost entirely 

 confined to the skin, but they also narrowly tip the lower 

 edges of the scales. The chin and throat are white, with 

 light sky-blue and yellow mottlings. It is a remarkable fact 

 that there is no green pigment responsible for the brilliant 

 colouring of the snake. If the scales are viewed through 

 a lens, they are seen to be studded with minute specks of 

 bright yellow, and as the skin is of a bright blue colour the 

 jrellow specks convert this into green. The yellow pigment 

 present is soluble in spirit, and imparts its colour to this 

 fluid. It is also soluble in hot water, for if the skins are boiled, 

 they lose their pigment and become blue, whilst the water 

 becomes tinged with yellow. In most specimens the throat 

 will show patches of sky-blue where not overlaid with this 

 yellow pigment. The blueness of the skin, when robbed of its 

 yellow, is due to a colour effect, and not to a blue pigment. 

 Light passing through the translucent epithelium is broken 

 up, the blue rays only boing reflected, whilst the other 



