72 INTRODUCTION 



are proof against the poison of the Crotalines which 

 frequent the same districts, and which they are able 

 to overpower and feed upon. The Cribo, Spilotes 

 variabilis, is the enemy of the Fer-de-lance in St. 

 Lucia, and it is said that in their encounters the 

 Cribo is invariably the victor. Repeated experi- 

 ments have shown our Common Snake, Tropidonotus 

 natrix, not to be affected by the bite of Vipera berus 

 and V. aspis, this being due to the presence, in the 

 blood of the harmless snake, of toxic principles 

 secreted by the parotid and labial glands, and 

 analogous to those of the venom of these Vipers. 



The Hedgehog, the Mungoose, the Secretary Bird, 

 and a few other birds feeding on snakes, are known 

 to be immune to an ordinary dose of snake poison ; 

 whether the pig may be considered so is still un- 

 certain, although it is well known that, owing to its 

 subcutaneous layer of fat, it is often bitten with 

 impunity. The Garden Dormouse (Myoxus quercinus) 

 has recently been added to the list of animals 

 refractory to Viper poison. 



