376 REPORT OF NATIONAL MUSEUM, 1893. 



iiijiy liapprii to l)e in the same box. So soon, however, as cause is seen for alarm, 

 the snake extricates itself, if among others, and at once throws its 1)o(iy into the 

 coil 80 familiar to any one who has seen ser]>ent8, whether venomous or not. Some- 

 times on the edge, more often in the center of the coil, the tail projects far enough 

 to admit of its vibrnting freely and with singular swiftness. The head is raised a 

 little above the rest of the body, but not usually more than 8 or 4 inches, even in 

 large snakes. The neck and ujtper end of the trunk are not thrown into complete 

 circles, but lie in two or three abrui)t curves across the mass of the coiled body. 

 The suake is now in position to strike. While thus at bay, in an attitude of singu- 

 lar grace, the long black tongue is frequently protruded — a common movement among 

 all serpents when irritated. Just before the Idow the snake makes a hissing sound, 

 which is caused by the act of expiration, and is due to the passage of air through 

 the narrow glottis. It is louder in certain innocent serpents than in the crotalus. 



The mechanism of the forward cast of the body, which next occurs, is a very 

 simple matter. The muscles which lie upon the convexity of the bending formed 

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

 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 suake has 

 struck the end of a pole which I was holding, iku- could it alone suffice to bury the 

 fang in a tough skin were it not for the acts which follow and aid it. In efl'ectiug 

 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 eiuible it to strike downward. It seems, however, 

 to be of no moment in what direction the danger threatens, since it can at will 

 cast itself forward, downward, or almost directly upward. 



As the animal comes within reach, of which tin; suake 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 lirst cervical bones, so as to bring the point of the fang into a favorable 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 stand- 

 ing 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 bodj' 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 cer- 

 vical jtrolongation of the mass of the spinal muscles, is capable of being bent back- 

 ward 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 decapitating the snake, and, although some French observers 

 seem to have had doubts as to the agencies which eff^ect the elevation and depression 

 of the fang, there does not seem to me to be any reason to doubt the share Avhichthe 

 spheno-pterygoid takes in this mechanism. That the mere act of opening the mouth 

 of necessity raises the Aveapon has often been affirmed, but it is only necessarj' to 

 separate the jaws of a crotalus to be convinced that this is not the case, and that 

 even wlien 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 maxillary bone rocks forward upon its lachry- 

 mal articulation. When the motion reaches its limit, and is checked by the liga- 

 ment which I have described, the supporting lachrymal l)one, in turn, yields to the 



