DO SNAKES INCUBATE 1 435 



and some lizards are suspected of doing the same. Even 

 our common ring snake has been found coiled upon her 

 eggs. 



Serpents are allied to birds in producing young from 

 eggs, but in reptiles the eggs differ from those of birds in 

 undergoing a sort of incubation from the very first ; so that 

 at whatever period a snake's ^^^ is examined, whether it 

 has been laid or not, the embryo will be found more or 

 less advanced. Sometimes in an t^^ just deposited, a 

 perfectly formed foetus will be found. * Serpents are 

 always oviparous,' says Schlegel ; 'and it is a mistake to 

 suppose that all venomous snakes produce live young, 

 and all non-venomous kinds lay eggs. Neither has the 

 diversity of generation any relation to the organization of 

 the animal itself Coronella Icevis produces living young, 

 but other coronellas lay eggs. In 1862, when very little 

 was known of the Coronella IcBvis, Mr. Frank Buckland had 

 one in a cage in London, which to the surprise of most 

 persons produced live young ones. This may have ^been 

 solely owing to her captivity and her retention of eggs till 

 hatched. Some boas lay eggs, others are viviparous. In 

 the latter case the young are enclosed in a thin membrane, 

 which they tear or break at the moment of birth. In those 

 that are a long while hatching, the tunic is of a thick, 

 coriaceous texture, not easily ruptured. Thus, to sum up 

 with one other authority, I>er Hoeven : * In many serpents 

 and lizards the development begins in the body of the 

 parent before the ^^^ is laid, and in some the membrane of 

 the ^^^ is broken by the young one before birth.* 



This latter condition has been considered viperinc, but 



