Hurler — Herpetology of Missouri. ■ 217 



a poisoner close to the Cobra, and the Crotalidae are rep- 

 resented by a number of snakes which are somewhat less 

 effective slayers than the Cobra. All of the great family 

 of Vipers have substantially the same mechanical arrange- 

 ment for injecting their venom. When not in action the 

 two hollow teeth known as fangs lie pointing backwards, 

 wrapped in a loose cloak-like cover, a fold of the soft skin 

 of the interior of the upper jaw. At the base of each of 

 these fang teeth is an opening connected with a tube run- 

 ning backwards under the eye to an almond-shaped gland 

 which forms the poison. This gland holds in its cavity 

 a supply for use. Over the gland runs a strong muscle, 

 which is ordinarily employed to close the mouth by lifting 

 the lower jaw, to which it is made fast. A little circular 

 muscle around a part of the duct keeps it shut and pre- 

 vents waste of venom. 



"Previously we have left the snake thrown into i'^ 

 coil, carrying its head ready for an attack. The snake 

 does not pursue but waits. Little animals he scorns unless 

 he is hungry, so that the mouse or the toad he leaves for 

 days unnoticed in his cage. Larger or noisy creatures 

 alarm him. Then his head and neck are thrown far back, 

 and with an abrupt swiftness the jaws widely separated, 

 he strikes once and is back on guard again, vigilant and 

 brave. The blow is a stab, and is given by throwing the 

 head forward while the half-eoils below it are straightened 

 out to lengthen the neck and give power to the motions 

 which drive the fangs into the opponent's flesh; as they 

 enter, the temporal muscle closes the lower jaw on the 

 part struck, and thus forces the sharp fang deeper in. 

 It is a thrust aided by a bite. At this moment the poison 

 duct is opened by the relaxation of the muscle which sur- 

 rounds it, and the same muscle which shuts the jaw 

 squeezes the gland, and drives its venom through the duct 

 and the hollow fang into the bitten part. 



''In so complicated a series of acts there is often fail- 

 ure. The tooth strikes on tough skin and doubles back 



