OF THE VENOM OF THE RATTLESNAKE. 21 



simple matter. The muscles which lie upou the convexity of the bendings formed 

 by the upper part of the snake, are suddenly and violently contracted, so as 

 abruptly to straighten the body, and thrust it forward in a direct line. The force 

 resulting from this motion is not very great, as I have often ascertained when a 

 snake has struck the end of a pole which I was holding, nor would it alone suffice 

 to bury the fang in a tough skin, were it not for the acts which follow and aid it. 

 In effecting this forward thrust of the neck and head, the serpent employs only 

 the upper part of its body, and, consequently, is unable, under any circumstances, 

 to strike at a greater distance than one-half its length, while usually its projectile 

 range does not exceed a third of its length. An impression prevails that when 

 the snake lies coiled, its head is raised very high to enable it to strike downwards. 

 It seems, however, to be of no moment, in what direction the danger threatens, 

 since it can, at will, cast itself forwards, downwards, or almost directly upwards. 



As the animal comes within reach, of which the snake does not always judge 

 with accuracy, the latter executes the movement just described. At the instant, 

 and while in motion, the jaws are separated widely, and the head is bent somewhat 

 back upon the first cervical bones, so as to bring the point of the fang into a favor- 

 able position to penetrate the opposing flesh. Owing to the backward curve of the 

 tooth, this, of necessity involves the opening of the jaws 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 peculiar articulation of the lower jaw upon an 

 intermediary bone, in place of upon the body of the skull, greatly facilitates this 

 action. On examining the neck and head, it will also be seen that the head, under 

 the influence of the cervical prolongation of the mass of the spinal muscles, is 

 capable of being bent backwards to no inconsiderable extent. Consentaneously 

 with the forward thrust of the body, and with the opening of the mouth, the 

 spheno-pterygoids act from their firm cranial attachments to draw forward the 

 pterygoid plate, and thus, through its attachment to the maxillary to erect the 

 fang. The function of elevating the fang belongs alone to this muscle, which has 

 no analogue in the other vertebrate animals. I have frequently tested its power 

 to raise the fang, by stimulating it with galvanic or other irritants, after decapi- 

 tating the snake, and although some French observers seem to have had doubts as 

 to the agencies which effect the elevation and depression of the fang, there does- 

 not seem to me to be any reason to doubt the share which the spheno-pterygoid 

 takes in this mechanism. That the mere act of opening the mouth, of necessity 

 raises the weapon, has often been affirmed, but it is only necessary to separate the 

 jaws of a living Crotalus to be convinced that this is not the case, and that even 

 when the mouth is widely opened, the animal has the most perfect control over 

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



As the spheno-pterygoid acts, the submaxillary bone rocks forward upon its 

 lachrymal articulation. When the motion reaches its limit, and is checked by the 

 ligament which I have described, the supporting lachrymal bone, in turn, yields to 

 the power applied through the maxillary bone. These movements elevate a little 

 the muzzle of the snake, so as to give to the face a very singular expression during 

 the act of striking. Their more obvious and important result, is the elevation of 



