172 THE THEORY OF EVOLUTION 



which has been effective through long periods, has 

 made itself felt. 



The conclusions thereby arrived at form one of 

 the main supports of the transformation hypothesis 

 and the best refutation of the absolute fixity of species 

 which was formerly accepted. 



The most favourable conditions are presented in 

 the first place by the small oceanic islands which owe 

 their existence to submarine volcanic outbreaks. We 

 will first give a few examples in detail ; subsequently 

 we will collect the points of evidence which speak 

 for transformation as actually established. 



1. The Azores and Bermuda Islands (both of vol- 



canic origin). 



Azores (1400 Km. from Portugal) : 



69 Snail species, 32 ' indigenous' ) the rest 

 53 Bird species, 1 j European. 



Bermuda (about 1400 Km. from America) : 

 Many Snails one-fourth indigenous, the others 

 American. 



2. St. Helena (1800 Km. from Africa, 3000 Km. 



from S. America) : 



Land Vertebrates entirely absent. 



Land Birds 1 species (Regenpfeifer) indigenous. 



Land Snails 20 species, all indigenous, with- 

 out nearer relationship. 



Beetles 129 species (128 indigenous) ; they are 

 divided into 25 genera, all indigenous ; two- 



