68 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



next phase is the forward cast of the body, which is effected by a sudden 

 contraction of the muscles which lie upon the convexity of the bendings 

 formed by the upper part of the snake, so as to abruptly straighten the body 

 and thrust it in a direct line. The projectile range does not exceed a third 

 of its length. The snake can cast itself in every direction forwards, down- 

 wards, or almost directly upwards. At the instant, and while in motion, the 

 jaws are separated widely, and, in order to bring the points of the backwardly 

 curved fangs into a favorable position to penetrate the opposing flesh, this 

 is done to such an extent that an observer standing above the snake can see 

 the white mucous membrane of the mouth as the blow is given. The for- 

 ward thrust of the body and the opening of the mouth are instantaneously 

 accompanied by the contraction of the spheno-pterygoids of the pterygoid 

 plates, which, through their articulation with the maxilla, bring the fangs to 

 the erect position. The mere act of opening the mouth is not necessarily 

 associated with the erection of the weapon, but, on the contrary, even when 

 the mouth is widely opened, the snake has the most perfect control over the 

 movement of the fang, raising or depressing it at will. At the same moment 

 the cloak-like vagina-dentis is thrust off from the convexity of the fang and 

 is gathered in loose folds at its base. When the erected fangs penetrate the 

 flesh a second series of muscular movements follows. The contraction of 

 the spheno-pterygoid is relaxed and is immediately succeeded by contraction 

 of the pterygoid externus and spheno-palatine. The latter movement, due 

 to the insertion of the posterior apophysis of the maxillary bone and the 

 inside of the palatal bone, respectively, draws the point of the fang violently 

 backwards, so as to drive it more deeply into the flesh. 



At this instant occurs a third series of motions which result in the further 

 deepening of the wound and the injection of the venom. The lower jaw is 

 closed upon the bitten part or member. The closure is effected by the pos- 

 terior, middle, and anterior temporal muscles. The first two tend simply 

 to shut the mouth, but the anterior temporal is so folded about the poison 

 gland that while it draws up the lower jaw, it simultaneously compresses 

 two-thirds of the body of the gland. This force is applied in such manner 

 as to squeeze the venom out of the upper and posterior parts of the gland 

 and drive it forward into the duct. The middle temporal muscle descends 

 from its attachment at the temporal fossa to its thin fan-like insertion over 

 the external surface of the anterior and posterior temporal muscles, passing 

 downwards in a slightly oblique anterior direction along the inner surface 

 of the posterior one-third of the poison gland, and crossing, in part, that 

 portion of the anterior temporal which is wrapping up the anterior two- 

 thirds of the gland by a curved course which it takes from the front to the 

 rear, where it ends in the capsule of the gland. Thus, the contraction of 

 this muscle exerts also an important rdle in compressing the gland. The 

 anterior lower part of the gland and a portion of the duct is subjected to the 

 pressure at the same instant, owing to the flat tendinous insertion of a part 

 of the external pterygoid upon the parts in question. 



