COMMON VIPER. 63 



is not at all improbable, considering how instantaneously the 

 poison begins to affect small animals, that even in the act of 

 seizing a mouse or bird, or any other victim, it may instil 

 a sufficient quantity of venom into its system to paralyze 

 and presently destroy it. Still the action by which it takes 

 its prey is very different from that which it employs in its 

 defensive attack, and resembles that employed by the in- 

 nocuous tribes. Its favourite food consists of the smaller 

 mammalia, field-mice, shrews, and similar little animals, of 

 frogs also, though less commonly, and occasionally of birds. 

 It does not always confine its voracity within the limits of its 

 powers of deglutition ; for I have in my possession a specimen 

 of a small Viper which was taken on Poole Heath in Dor- 

 setshire, in a dying state, in the act of attempting to swallow 

 a mouse which was too large for it, the skin of the neck 

 being so distended as to have burst in several places. 



The Viper, like many others of the poisonous groups of 

 Serpents, is ovo-viviparous. I have concluded, from the 

 examination of many specimens both of this species and of 

 the Rattlesnake, that it is in the act of parturition that the 

 membrane of the egg is burst. I have examined several in 

 which the young have appeared ready to be excluded ; but 

 have always found the investing membrane entire, although 

 so thin and soft as to be torn by the slightest force. I give 

 a figure of the young Viper in this state, the membrane 



