12 JOURNAL, NATURAL HIST. SOCIETY OF SIAM. Vol. I. 
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. 
Stamese. 3 UG ariel (ngu saang athit ). The) largest of 
all the Tae snakes that inhabit Bangkok, where it is fairly 
common. It 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, usually 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. unieolor it is so strongly aud rapidly performed that I have at times 
thought I could actuaily 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. Ruts, mice, frogs and other snakes. 
- Dimensions. 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 Y. have seen measured from snout to 
vent 860 mm., tail 75 min. 
Colour (in life). Above, from black or an intense bluish black 
to chocolate brown, uniform, the last 3 rows of costal scales being 
edged with white. 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. 
