Chap. IX.] 
TKEE-SNAKES. 
307 
nized from its bright colour and from the pointed move- 
able appendage, into which the snout is prolonged. The 
snakes of this genus being active chiefly during the 
night, the pupil of the eye is linear and horizontal. 
They never willingly descend from trees, but prey 
there upon nocturnal Saurians, geckoes, small birds and 
their young ; and they are perfectly harmless, although 
they often try to bite. It is strange that none of the 
numerous specimens which it has been attempted to 
bring to Europe have ever fed in captivity ; whilst in 
South America they take their food freely in confine- 
ment, provided that some green plants are placed in 
their cage. 
In Ceylon I have never seen any specimen of a 
larger size than three feet ; whilst they are known to 
attain to more than five on the Indian Continent. 
The inference is obvious, that the green coloration 
of the majority of tree-snakes has more or less con- 
nection with their habits and mode of life. Indeed, 
whenever a green-coloured snake is observed, it may at 
once be pronounced, if slender or provided with a pre- 
hensile tail, to be of the kind which passes its life on 
trees; but if it be short-bodied then it lives on the 
prairies. There are nevertheless tree-snakes which have 
a very different coloration; and one of the most re- 
markable species is the Passerita fusca or Dryinus 
fuscus, of which a figure is annexed. It closely re- 
sembles the green Passerita in form, so that natu- 
ralists have considered it to be a mere variety. It is 
entirely of a shining brown, shot with purple, and 
the yellow longitudinal stripe which runs along the 
side of the belly of the green species, is absent in this 
one. It is much more rare than the green one, and 
x 2 
