12 JOURNAL, NATURAL HIST. SOCIETY 01^ SIAM. Vol. L 



back, but become gradually obscured in later life, although by careful 

 examination traces of them can usually be found. The tail has a 

 reddish or orange mark, and there is often a collar of the same 

 colour. 



Family Xenopeltidae. 



6. Xenopeltis unicolor. 



Siamese. ^ UC^^ mmU ( ng^^ saang athit ). The largest ot 

 all the burrowing snakes that inhabit Bangkok, where it is fairly 

 common. ]t is found frequently in the saw-mills, hiding away in the 

 stacks of wood or beneath the squares. It is found also in the gardens 

 when turning up the ground, and beneath heaps of leaves and rubbish. 

 In loose soil it can burrow rapidly and easily, and in capitivity, like 

 the preceding species, U'^n.ally disappears immediately into the earth 

 of its cage. It appears to be entirely nocturnal in its habits. It is 

 an active powerful snake and when first caught, although it will make 

 violent efforts to escape, and wrap itself round one's hand and fingers 

 with great constricting force, does not attempt to bite. It has the 

 curious habit when excited of vibrating the tip of its tail with great 

 speed. The habit is by no means confined to this species, but with 

 X. unicolor it is so strongly and rapidly performed that I have at times 

 thought I could actually hear the vibrations. 



The Siamese name, '■■ ngu saang athit, " the sunbeam snake, is 

 well deserved. The high polish of every scale in its body, and the 

 beautiful tints, chiefly of sapphire blue and emerald green, which flash 

 forth from the upper surface ( although the actual colour is uniform 

 black or dark brown), make it a very striking creature in appearance. 

 Food. Eats, mice, frogs and other snakes. 

 Dimeihsions. Grows to a length of 1200 mm. (4 ft.). The tail 

 is very short, measuring only about one-tenth of the body length. 

 The largest Bangkok specimen I have seen measured from snout to 

 yent 860 mm., tail 75 mm. 



Colour (in life). Above, from black or an intense bluish black 

 to chocolate brown, uniform, ^he last 3 rows of costal scales being 

 edged with M'hite. Beneath, white, immaculate, except for the sub- 

 caudal scales which are edged with dark grey. The young are black 

 above with a white or yellowish collar extending on to the occiput. 



