578 AMPHIBIALA. 



tailed by Mr. Bruce, who, in the course of his travels, had fre- 

 quent opportunities of contemplating it in its native regions. 



*< The cerastes," says Mr. Bruce, <l inhabits the greatest part 

 of the Eastern Continent, especially the desert sandy part of it. 

 It abounds in the three Arabias, and in Africa. I never saw so 

 many of them as in the Cyrenaicum, where the Jerboa is frequent 

 in proportion. He is a great lover of heat ; for though the sun 

 was burning hot all day, when we made a fire at night, by digging 

 a hole, and burning wood to charcoal in it, for dressing other vic- 

 tuals, it was seldom we had fewer than half a dozen of these vi- 

 pers, who burnt themselves to death by approaching the embers. 

 The general size of the cerastes, from the extremity of its snout 

 to the end of the tail, is from thirteen to fourteen inches ; its head 

 is triangular, very flat, but higher near where it joins the neck 

 than towards the nose : the length of its head, from the point of 

 the nose to joining of the neck, is ten twelfths of an inch, and the 

 breadth nine twelfths : between its horns is three twelfths : the 

 opening of its mouth, or rictus oris, is eight twelfths : its horns in 

 length three twelfths : its large canine teeth something more than 

 three twelfths and a half: its neck, at the joining of the head, four 

 twelfths : the body, where thickest, ten twelfths : its tail, at the 

 joining of the body, two twelfths and a half: the tip of the tail 

 one twelfth : the length of the tail one inch and three twelfths : 

 the aperture of the eye two twelfths, but this varies, apparently 

 according to the impression of light. The cerastes has sixteen 

 small, immoveable teeth, hollow, crooked, inwards, and of a re- 

 markably fine polish, white in colour, inclining to blueish ; near 

 one fourth of the bottom is 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 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 aperture, 

 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 

 Tenom 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 posi- 

 tion of the tooth along the jaw, and its being defended by the mem* 



