CROTALIDA. 83 
responding muscles attached to the sides of the angle of the 
mouth, and controlled by the will of the reptile. 
This fang is (in large individuals) from five-eighths of an 
inch to an inch in length, with a broad base or root, and very 
securely attached to one of the side-bones of the head. ‘These 
bones are attached to the anterior and posterior shield-like 
bones of the head by a strong but flexible cartilage, which, 
yielding in every direction, permits a certain amount of move- 
ment to the base of the fang. The external portion of the 
fang is exceedingly hard and tough in its anterior part; and 
close to its point of attachment to the side-bones, it is per- 
forated by a minute canal or tube, which extends down to 
the extreme lower point of the fang, terminating in an open- 
ing or slit of a double convex shape. This tube is entirely 
disconnected from all the inner portion of the root, nerves, 
or bloodvessels which nourish its bony mass. Just back of 
and below the eye, there is a slight concavity or depression 
in the upper mandibule, which contains a small sac or dimin- 
utive bladder, containing from six to twenty-five drops of 
poison. This small bladder terminates on one side in a 
threadlike tube, which passes through a perforation in the 
posterior wall of its concavity, and, passing inside and behind 
the buccal glands, is attached to the upper mouth of the chan- 
nel in the fang. 
On the other side the bladder is connected with the poison- 
gland and its secretory apparatus, which is so clearly de- 
scribed by Dr. Mitchell.* The South American varieties 
have a distinctly formed poison sac or bladder, as just de- 
scribed; and I have frequently taken from a snake six feet 
long twenty drops of venom from each fang, making forty 
drops in all. Although Dr. Mitchell says he could never 
procure more than five or six drops at a time, and then only 
— 
* Researches, &c , on the Venom of the Rattlesnake. 
