380 



SERPENTS. 



siognomy are so peculiar, and the impression wliicli 

 their look creates is so vivid, that they may, for the 

 most part, be immediately recognised by any one 

 who has ever attentively examined a single species. 

 " Their jaws are generally weak ; the under one is 

 provided with a series of sharp-pointed teeth, but the 

 upper jaw is destitute of any, except the moveable 

 poison fangs. The head is extremely broad, flattened 

 on the crown, and heart-shaped or triangular. In- 

 stead of being covered by plates, as in the harmless 

 races, it is clothed in scales similar to those of the 



Fig. 311. — heads of poisonous snakes of different genera. 



back. Their eyes are small, have a vertical puiDil, 

 are deep sunk in the sides of the head, and over- 

 shadowed by the projecting plates of the eyebrow. 

 The upper lip is swollen, and hangs down in order to 

 conceal the long fangs. In form they are heavy and 

 squat, the body being pretty thick in the middle, 

 somewhat compressed ; the back slightly keeled, 

 covered with rough keeled scales, while the belly is 

 covered with broad band-like shields or scuta. The 

 tail is short, conical, and thick, but never blunt at the 

 tip. 



" Their manners, habits, and method of killing their 

 prey are very characteristic. Their dull, heavy dis- 



