234 BRITISH REPTILES 



may at once be distinguished from the Adder by 

 the absence of any dark markings, and also by its 

 larger size. 



The Adder can be identified by the V-shaped 

 mark on the head and also by the dark zigzag line 

 that runs from the head right down the centre of 

 the back to the tail. It rarely exceeds eighteen 

 inches in length, and is brown to black in colour. 



Doubtless many of you have been interested 

 in seeing the Snakes at the London Zoo and else- 

 where, and observed the creatures thrusting out 

 their forked tongues rapidly. Many persons mis- 

 take this for a " sting," whereas it is quite a harm- 

 less organ, and serves a far different purpose. 

 The " stinging " process in a venomous Snake is 

 carried out by means of two fangs situated in the 

 upper jaw. These fangs point inwards, and are 

 very sharp. The poison is secreted in a gland 

 above the upper jaw, and when the Adder, for 

 example, strikes a person, the venomous sub- 

 stance, or poison, is sent down a kind of little tube 

 in the fang, and is then driven into the wound 

 caused by the fangs. 



The Grass Snake differs also from the Adder in 

 its method of reproduction, for, whereas the former 

 lays from twenty-four to forty-eight leathery- 

 shelled eggs in a manure heap, and leaves them 

 to be hatched by the warmth afforded, the 

 female Adder hatches out her thin-shelled egg in 



