1 96 E VOL UTION OF TO-DA Y. 



have been derived by descent with modification, 

 assisted by the isolated situation of the islands. 



A still more interesting case is that of St. Helena. 

 This is a small island wholly volcanic, very old, and 

 situated more than eleven hundred miles from Africa 

 and eighteen hundred miles from South America. 

 Its isolation is therefore very complete. It can have 

 received only a few immigrants, but these few find- 

 ing the whole field to themselves have had abundant 

 opportunity to develop ; and since the island is very 

 old, some of them will have had time enough to be- 

 come very much modified. We may expect more 

 peculiar forms than in the Galapagos islands. With- 

 in historical times this island has been much altered 

 by human agency, and many new plants and animals 

 have been introduced. Eliminating this factor, the 

 fauna and the flora of the island are truly remarkable. 

 There is only one vertebrate found a wading bird 

 allied to African forms, but a distinct species. The 

 distance from the continent has proved too great 

 for the passage of all kinds of vertebrates. There are 

 no fresh-water animals. Of land shells a few species 

 are known, more than half of which are extinct, and 

 the rest so peculiar as to have no very near relatives 

 anywhere. Of plants seventy-six species have been 

 found, fifty of which belong to the island alone, and 

 " cannot be regarded as very close allies to any 

 other plants at all." The most interesting group 

 of all is the order of beetles. There are one hundred 

 and twenty-nine species of beetles, all but one of 

 them found nowhere else on the globe. But this is 

 not all ; for while the specific peculiarity is greater 



