104 THE SNAKES OF SOUTH AFRICA. 



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 Rackio- 

 dontincB, 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 actuall}- 

 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 bon}^ 

 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 



