898 16. CROTALIDEA 
the head elevated, the tail projecting and rapidly vibrating. 
At the approach of the intended victim, the serpent, by 
sudden contraction of the muscles upon the convexity of the 
curves, straightens out the anterior portion of the body, and 
thus darts forward the head. At this instant, the jaws are 
widely separated, and the back of the head fixed firmly upon 
the neck. With the opening of the mouth, the spheno-pala- 
tines contract, and the fangs spring into position, throwing 
off the sheath as they leap forward. With delivery of the 
blow and penetration of the fangs, the lower jaw closes 
forcibly, the muscle that executes this movement causing 
simultaneously a gush of venom through the tubular tooth 
into the wound. There are also some secondary actions, 
though all occur at nearly the same instant. The mouth, 
fixed at the wound, drags upon it with the whole weight of 
the snake’s body. This dragging motion is accompanied by 
contraction of the ectopterygoid and spheno-palatine muscles, 
which ordinarily fold back the tooth; but the fang being 
at this moment engaged in the flesh, the action of the 
muscles only causes it to bury itself deeper, and thus enlarge 
the puncture. The train of action seems to be, the reaching 
of the object, the blow, the penetration, the injection of the 
poison, and the enlargement of the wound. These actions 
completed, the serpent loosens its hold by opening the jaws, 
and disengages itself, sometimes not without difficulty, 
especially when the bitten part is small and the numerous 
small teeth have caught. The head is withdrawn, the fangs 
folded, the mouth closed, and the former coiled attitude of 
passive defense is resumed. 
“While the venomous properties of these reptiles, not 
easily overrated, should suffice to ensure due caution in cap- 
turing or killing them, it is as well to remember that the 
utmost range of a rattlesnake’s blow is less than its own 
length. They may readily be captured alive by pinning down 
