ORDER OPHIDIA. oOl 



neath, so that they cannot act without compressing the gland, 

 and impelling the poison into its excretory canal, which con- 

 ducts it to the base of the fangs, where it penetrates by a 

 cleft, which prevails throughout their whole extent, and opens 

 towards the point obliquely, like the cut of a pen. 



When the irritated animal bites its victim, the fangs are 

 raised upright, they penetrate into the flesh, and deposit there 

 the fatal poison, the certain germ of death and destruction. 

 But they do not deserve, properly speaking, the appellation 

 of mobile fangs, by which certain naturalists have designated 

 them. It is not the teeth which raise themselves upright, 

 but, as we have already observed, it is the maxillary bone 

 which moves them. 



The ophidians have no epiglottis, and their pharynx, only 

 a little wider than the oesophagus, has no muscle destined to 

 move it, or cause it to change form. The mucous membrane 

 by Avhich it is lined, presents a number of longitudinal 

 folds. 



Their oesophagus is very dilatable, preserves pretty nearly 

 the same diameter throughout its whole extent, and is not 

 very precisely distinguished from the stomach, so that it is 

 very difficult to indicate, in a very exact manner, the situa- 

 tion of the cardia. The fleshy membrane of this conduit is 

 also very little marked. 



Their stomach has simply the form of a gut a little wider 

 than the rest, and without curvature. When its j}arietes are 

 contracted, its internal membrane constitutes longitudinal 

 folds. The pylorus is only marked by a slight contraction 

 and by a greater thickness of the parietes. 



In consequence of the kind of aliments with which these 

 reptiles are supported, their intestinal canal is very short, 

 and in the collared adder, for example, it is to the total 

 length of the body in the relation of one to one and a half. 

 It is long and slender, in the first part of its course, to which 



