POISONOUS SNAKES 115 



THE NIGHT ADDER. This is another viper which 

 is very common in south Africa. It is often found in 

 and near dwellings, and, like the puff adder, is so sleepy 

 by nature, that it is liable to be trodden upon accident- 

 ally. The bite, though dangerous, is not necessarily 

 fatal, and the reptile, being not more than a foot long, 

 cannot strike very high. I have often seen my cats 

 eating night adders which they had caught and killed. 



This species lays eggs. 



THE HORNED ADDER, also a dangerous viper, is usually 

 found in sand regions, and frequents the western portions 

 of south Africa ; an allied species the Horned Purl Adder 

 exists in the Transvaal and other parts of the sub- 

 continent. Both have a nasty habit of lying concealed 

 in loose sand, where they are practically invisible until 

 trodden upon. These two species have little horn-like 

 scales above the eyes. 



Several species of vipers are burrowers by habit, and 

 so are not often met with ; but all are poisonous and 

 dangerous. 



Besides the cobras and the vipers, there are a large 

 number of species known as Back Fanged snakes, a term 

 which means that their poison fangs are set, not in front, 

 but far back in their jaws. It is therefore much more 

 difficult for these snakes to inflict a bite than it is for 

 the front fanged snakes to do so. In fact for a long time 

 it was assumed that these back fanged snakes were 

 harmless, though it is now known that if they can secure 

 a grip they can many of them inflict a most dangerous 

 bite. 



Of these is the Tree Snake or Boomslang which, like 

 the mamba, may range in colour from green to black, 

 and has a conspicuously large eye. It attains to as much 

 as five feet in length. 



