104 THE SNAKES OF SOUTH ARKICA: 
toothless. The Egg-eating Snakes vary a great deal in colour- 
ation, according to the district in which they are found. On 
account of such differences, they have been divided into six 
varieties. Four out of the six varieties are found south of the 
Zambesi, the other two occurring in Central and Northern Africa. 
The sub-family name applied to the Egg-eating Snake is Rachto- 
dontineg, which means having enamel-tipped tooth-like pro- 
jections in the spine, penetrating the gullet. These snakes are 
found in all parts of South Africa, but are nowhere common. 
Their average length is three feet. 
EVOLUTION OF THE EGG-BREAKING MECHANISM. 
In proportion to the degree in which this species of snake 
took to feeding upon eggs, its teeth dwindled in size and number, 
and to-day it only possesses a few, which are quite rudimentary, 
and cannot be detected unless the snake’s jaws be dissected. 
In the act of swallowing eggs, teeth were of no use to the snake ; 
in fact, they were a distinct hindrance, so Nature took them away, 
and specially provided for the altered habits of this creature in 
a most wonderful and unique manner. It reads almost like a 
fairy tale, but it is nevertheless true that the Egg-eater actually 
has teeth in its backbone. For all practical purposes they are 
teeth, but in a strict scientific sense they are little bony pro- 
jections jutting out from the backbone of the neck. They 
project forwards, and downwards into the gullet, and are tipped 
with enamel. There are about thirty altogether. The smaller 
“teeth ’’ start from the base of the skull, and in full-sized snakes 
continue for two and a half to three inches down the backbone, 
terminating in six or seven others a little more prominent, and 
more freely coated with enamel. These larger “ teeth ”’ are for 
the purpose of sawing through strong hard shells which the smaller 
teeth cannot negotiate. Below these, there are seven bony 
projections almost a quarter of an inch long. These are not 
tipped with enamel. They, like the others, project into the 
gullet, pointing at an angle towards the mouth. When the 
snake swallows an egg, it, by means of these projections, 
keeps the egg in position until it is sawn through by the other 
teeth. They are also used as an aid in helping the snake to 
cast out the crumpled egg-shell, and ensuring that no pieces 
