Permanence and Evolution. 55 



warren nearly in a state of nature breed true, 

 but a warren must not be stocked with both 

 silver-greys and the common kind, otherwise 

 in a few years there will be none but common 

 rabbits living, through prepotence in intermix- 

 ture evidently. 



In the Falkland Islands there are feral rabbits 

 of various colours, but "how the rabbits were 

 coloured which were turned out is not known." 

 The Porto Santo rabbit is supposed to be a 

 striking instance of transmutation. In the 

 island of Porto Santo there are wild rabbits much 

 smaller than English rabbits, remarkably wild 

 and active (more like large rats than rabbits), 

 nocturnal to a great extent in their habits, and 

 of exceptional wildness, and which it appears 

 breed not easily with other rabbits. They are 

 differently marked from common rabbits, but 

 here Darwin noticed differences in the same 

 individual, which he attributed to the English 

 climate, but which more likely arose from age 



