388 CERASTES. 



strongly fixed in the upper jaw, and folds back 

 like a clasp knife, the point inclining inwards, 

 and the greatest part of the tooth is covered with a 

 a green, soft membrane, not drawn tight, but as 

 it were wrinkled over it : immediately above this 

 is a slit along the back of the tooth, which ends 

 nearly in the middle of it, where the tooth curves 

 inwardly. From this aperture I apprehend that it 

 sheds its poison, not from the point, where, with 

 the best glasses, I could never perceive an aper- 

 ture, so that the tooth is not a tube, but hollow 

 only half way ; the point being for making the 

 incision, and by its pressure occasioning the ve- 

 nom in the bag at the bottom of the fang, to rise 

 in the tooth, and spill itself through the slit into 

 the wound. By this flat position of the tooth 

 along the jaw, and its being defended by the 

 membrane, it eats in perfect safety ; for the tooth 

 cannot press the bag of poison at the root while it 

 lies in this position, nor can it rise in the tube to 

 spill itself, nor can the tooth make any wound, so 

 as to receive it ; but the animal is supposed to eat 

 but seldom, or only when it is with young. This 

 viper has only one row of teeth ; none but the ca- 

 nine are noxious. The poison is very copious for 

 so small a creature, it is fully as large as a drop of 

 laudanum dropt from a vial by a careful hand. 

 Viewed through a glass, it appears not perfectly 

 transparent or pellucid. I should imagine it hath 

 other reservoirs than the bag under the tooth, for 

 I compelled it to scratch eighteen pigeons upon the 

 thigh as quickly as possible, and they all died nearly 



