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 rédle 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. 
