OP THE VENOM OF THE RATTLESNAKE. 23 



pterygoid, again acting, depresses the fang, and the serpent recovers its posture of 

 defence. 



It happens, not unfrequently, that the teeth of the lower jaw catch in the skni 

 of the bitten animal, and thus prevent the snake from retreating at once. When 

 this takes place, the serpent shakes its head from side to side, with a motion which 

 so nearly resembles the shake a dog gives his prey, that it has been mistaken by at 

 least one observer for an' expression of rage. It is really an attempt to escape ; 

 nor is it always successful, since a large animal will often drag a snake until the 

 fangs themselves break loose, and are left in, or on, the bitten part. 



In considering this portion of our subject, it is well to notice what has been too 

 much overlooked, the fact that, while the snake commonly employs both fangs, it 

 does often inliict but a single wound. When obtaining venom from living snakes, 

 I have been accustomed to allow them to bite upon the inner edge of a cup, and I 

 have observed that on some occasions both fangs were used at once, and that on 

 others only one was active. Or, the fangs were used in succession, an appreciable 

 interval of time intervening. If this occur, when a snake at freedom strikes an 

 object, it is, of course, possible that the animal may escape before the second fang 

 is driven in by the traction of its proper external pterygoid muscle. At all events, 

 it is certain that these facts should receive due appreciation, in estimating the 

 danger of a given bite, and the value of an antidote. 



There remains for consideration one muscular motion, which I have observed 

 " to accompany the effort to bite, when the snake is held by the back of the neck. 

 It consists in a turning outwards of the points of the fangs, so as to separate them 

 from one another.^ This divergence of the fang points is disadvantageous, inasmuch 

 as it causes them to enter somewhat obliquely, and frequently throws one fang 

 beyond the part bitten, when that part happens to be small. It has a use with 

 reference to the snake itself, since the fang-points, when thus widely separated, lie 

 outside of the lower jaw, and are thus prevented from wounding it. This purpose 

 is greatly aided by the action of a muscle analogous to the mylo-hyoid, which 

 approximates the anterior extremities of the lower maxillary, or mandibular bones, 

 so as to make narrow the extremity of the jaw. The protection thus obtained is 

 very essential, since the serpent always closes the jaw violently when biting, but 

 does not always succeed in seizing its prey. Whether or not this divergence of 

 the fang-points occurs when the snake bites unrestrainedly, I cannot say ; but as I 

 have been very often astonished at the distance between the wounds, where both 

 fangs had taken effect, it is highly probable that it occurs under all circumstances. 



We have still left for consideration certain points of minor interest, in connection 

 with the part played by the gland in the train of actions which I have described. 

 This organ, as we have seen, is violently compressed by the anterior temporal muscle, 

 and perhaps by the posterior temporal, as well as indirectly by the external pterygoid. 

 Under the pressure thus applied, the venom passes through the duct, and out of 

 the fang. Now, as it is clear that the temporal muscles must be often used to 



' I could not determine wbetber this divergence took place wlien tlie sualic, at freedom, struck an 

 animal. 



