CHAPTER XXIV. 



DO SNAKES INCUBATE THEIR EGGS? 



WE come now to treat of facts no less interesting than 

 surprising in ophidian biographies. Already we 

 have recounted almost marvellous powers possessed by 

 this class of animals — functions which are volitionary, 

 such as the management of their trachea, the voluntary 

 folding back or unfolding of certain teeth, the practical 

 adaptation of their ribs and coils to what we may 

 almost call manual work, and now, most astonishing of 

 all, the voluntary deposition or retention of ova, even of 

 young. 



* Snakes are either oviparous or viviparous,' is what we 

 are accustomed to read, followed by the explanation that 

 the former are those which lay eggs, and the latter those 

 which produce their young alive. To these two chief 

 distinctions, the more recent one of ovoviviparous has 

 been added, to describe some intermediate cases where the 

 Qgg is ruptured in parturition, so that again a fully-formed 

 young one is born. For broad distinctions the three terms 



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