THE XENODONS. 409 



of which Dr. Wucherer says, ' Dentition similar to Xenodon,' 

 the former had teeth gradually increasing a trifle posteriorly, 

 but nothing like fangs. L, cobella had a very long jaw of 

 fifteen or sixteen teeth, but no fangs. 



On . a second occasion I made a dental examination of 

 the living Xenodon in order to be fully convinced of the 

 nature of its back teeth, and in both instances the fangs 

 were depressed until the snake was provoked into display- 

 ing them.. It exhibited no spitefulness or attempt to bite, 

 and in both cases folded back its fangs the moment my 

 finger was removed, as if glad that the ceremony was over. 



Heterodon d'Orbignyi, being a small and delicate snake, 

 was not again enticed to exhibit its jaws ; but my for- 

 bearance was otherwise rewarded. One day it was dining 

 off a rather large frog, and its mouth, close to the glass, 

 was stretched open to its fullest extent. The frog had 

 disappeared so far as to be within the mouth, wedging 

 it wide open ; and I then saw a fang well erected and 

 in use, moving^ being detached, in fact, from the food. 

 It appeared to be somewhat nearer to the front than 

 Xenodons fangs, with perhaps only three or four simple 

 teeth before it. But that it was a sheathed fang- and mobile 

 I have no doubt whatever, having seen it very distinctly. I 

 told Tyrrell at the time that Heterodon' s fangs were also 

 moveable ; but now for the first time I impart this new secret 

 to the public. Xenodon also greedily seizes upon incon- 

 veniently large frogs, but it has never displayed its fangs 

 to me while feeding, as the pretty little Heterodon did. One 

 more singular thing did this little Heterodon, and that was 

 to assist itself by coiling its body round an unmanageable 



