468 THE SNAKES OF SOUTH AFRICA. 
The Viper Family of snakes have long hollow fangs. 
The Cobra Family have grooved fangs, not nearly so long as those 
of Vipers. ; 
All the Viper and Cobra Family of snakes are venomous. 
One of the Viper snakes of South Africa has taken to burrowing in 
the ground. In consequence, its body has become quite round (cylindrica)). 
The poison glands of these snakes are situated, one on each side of the head. 
These glands manufacture the venom <and store it up. 
When a snake bites, certain muscles wring the poison glands, causing | 
the venom to run through a narrow channel, and down the hollow or 
grooved fang. 
The Night Adder of South Africa is a remarkable exception to the 
general rule. Its poison glands extend for about three inches down its 
back. They lie on each side of the backbone, as seen in the illustration. 
Snakes eat rats and mice in great numbers. Rats and mice breed 
very quickly, and would soon become a great plague to us if their numbers 
were not kept in check. 
The Mole Snake and House Snake are quite harmless. They are both 
good rat-catchers. They are our friends, and should never be killed. 
Some snakes swallow eggs whole. They cannot suck eggs. 
The stomach juices dissolve the shell and release the contents. 
The Dasypeltis or Egg-eater Snake of South Africa has teeth in his 
backbone. ‘These are his saw. He swallows an egg, saws the shell, and 
spits it out. 
Snakes have many natural enemies. Mungooses, Meercats, and 
Muishonds eat them. So do most of the birds of prey. 
Most snakes are cannibals. They not only eat those of other species, 
but of their own too. 
Snakes do not chew their food. It is swallowed whole. 
Snakes do not cover their prey with saliva before starting to swallow it. 
Saliva runs abundantly into the mouth during the swallowing process, 
and lubricates the prey as it passes down the throat. 
When injured or alarmed, a snake will usually disgorge anything it 
may have swallowed. 
Pythons, Mole Snakes, House Snakes, and some other kinds of non- 
venomous snakes kill their prey by throwing two or more coils round it, 
and crushing it to death. 
Venomous snakes never constrict their prey. They kill or paralyze it 
with their venom. 
The forked tongue of a snake is not its sting. The tongue is very 
sensitive and acts as a feeler, like the tips of your fingers, or a cat’s whiskers. 
Most snakes live upon the ground, although the majority can climb. 
Others live almost entirely in trees. They are known as arboreal or 
Tree Snakes. 
Some kinds of snakes live entirely in water. All the Sea Snakes live 
in the ocean, and feed on fish and other marine creatures. 
The Sea Snakes are all poisonous. ‘They have a flattened oar-like tail 
for propelling themselves through the water. They breathe air like other 
snakes. 
