436 THE BOA CONSTRICTOR. 
head and opens its mouth to strike, the depressing muscles are relaxed, the 
© posite series are contracted, and the two deadly fangs spring up with their 
points ready for action. It is needful while dissecting the head to be 
exceedingly careful, as the fangs are so sharp that they penetrate the skin 
with a very slight touch, and their poisonous distilment does not lose its 
potency even after the lapse of time. 
There are generally several of the fangs in each jaw, lying one below the 
other in regular succession. From the specimen which has just been 
described, I removed four teeth on each side, varying in length from half to 
one-eighth the dimensions of the poison-fangs. 
The ordinary food of the Viper is much the same as that of the common 
snake, and consists of mice, birds, frogs, and similar creatures. It is, 
however, less partial to frogs than the common snake, and seems to prefer 
the smaller mammalia to any other prey. 
WE now arrive at a very important family of serpents, including the 
largest species found in the order. These snakes are known by the popular 
title of Boas, and 
scientifically as Boide, 
and are all remarkable, 
not only for their great 
size and curious mode 
of taking their prey, 
but for the partial de- 
velopment of their 
hinder limbs, which 
are externally visible 
as a pair of horny 
spurs, set one on each 
side of the base of the 
tail, and moderately 
. well developed under 
the skin, consisting of 
several bones jointed 
together. 
THE Boa CON- 
STRICTOR is a native 
of Southern and Tro- 
pical pe and is 
z one of those serpents 
BOA CONSTRICTOR.—(Boa Constrictor.) that were ions 
held sacred and wor- 
shipped with divine honours. It attains a very large size, often exceeding twenty 
feet in length, ar.d being said to reach thirty feet insome cases. It is worthy 
of mention, that before swallowing their prey the Boas do not cover it with 
saliva, as has been asserted. Indeed, the very narrow and slender forked 
tongue of the serpent is about the worst possible implement for such a pur- 
pose. A very large amount of this substance is certainly secreted by the 
reptile while in the act of swallowing, and is of great use in lubricating the 
prey so as to aid it in its passage down the throat and into the body, but it 
is only poured upon the victim during the act of swallowing, and is not 
prepared and applied beforehand. 
The dilating powers of the Boa are wonderful. The skin stretches to a 
degree which seems absolutely impossible, and the comparison between the 
diameter of the prey and that of the mouth through which it has to pass, and 
the throat down which it has to glide, is alinost ludicrous in its apparent 
