OF THE POISON-FANGS IN SERPENTS. 4*^1 
three ; &c. It is chiefly in the teeth of the Rattle-Snake * 
that I have observed the facts detailed in this paper, but I 
have also noticed the same appearances in some others, more 
particularly in the head of a large serpent, said to be In- 
dian, but closely resembling the African Puff-Adder. In 
some of the larger Cobras, the same appearances present 
themselves, but it is more difficult distinctly to make them 
out, by reason of the smallness of the poison fangs com- 
pared with those of the Rattle-Snake, f have thought, 
from some specimens examined by me lately, and more par- 
ticularly, from the one I now present to the Society, that 
the apparent fissure extending along the convex surface of 
the fangs in the Rattle-Snake may be forced open mechani- 
cally, even in the fixed fang, (for I do not suppose that there 
is ever actually a fissure in the fang of the Rattle-Snake); still 
there is no appearance of the poison canal ever being open 
on its convex surface "f*. The tedth in this serpent are ex- 
tremely brittle, and split longitudinally, whenever we at- 
tempt to cut them. 
The figures in the attached drawing are intended to ex- 
plain most of the anatomical facts mentioned in the paper: 
they were sketched from preparations now in my posses- 
sion. 
* Crotalus durissus. 
t It is easy to satisfy one*s self of the accuracy of this, by paring away the 
concave part of the tooth, and of the poison-canal, and examining the inner 
surface of the remaining convex portion ; it will then be quite evident that 
the poison-canal is never open on its convex side, excepting in the situation 
of the openings, for the entrance and escape of the poison. The vertical la- 
mina, and its firm union with the parietes of the tooth and of the poison- 
canal, is best seen by paring away the sides of the tooth, and leaving the 
convex part and the whole of the poison-canal entire. 
