244 



ISLAND LIFE. 



[part II. 



There is another reason for the very slight amount of pecu- 

 liarity presented by the fauna of the Azores as compared with 

 many other oceanic islands, dependent on its comparatively 

 recent origin. The islands themselves may be of considerable 

 antiquity, since a few small deposits, believed to be of Miocene 

 age, have been found on them, but there can be little doubt 

 that their present fauna, at all events as concerns the birds, 

 had its origin since the date of the last glacial epoch. Even 

 now icebergs reach the latitude of the Azores only a little to 

 the westward, and when we consider the proofs of extensive 

 ice-action in North America and Europe, we can hardly doubt 

 that these islands were at that time surrounded with pack-ice, 

 while their own mountains, reaching 7,600 feet high in Pico, 

 would almost certainly have been covered with perpetual snow 

 and have sent down glaciers to the sea. They might then 

 have had a climate almost as bad as that now endured by the 

 Prince Edward Islands in the southern hemisphere, nearly ten 

 degrees farther from the equator, where there are no land-birds 

 whatever, although the distance from Africa is not much greater 

 than that of the Azores from Europe, while the vegetation is 

 limited to a few alpine plants and mosses. This recent origin 

 of the birds accounts in a great measure for their identity with 

 those of Europe, because, whatever change has occurred must 

 have been effected in the islands themselves^ and in a time limited 

 to that which has elapsed since the glacial epoch passed away. 



Insects of the Azores. — Having thus found no difficulty in ac- 

 counting for the peculiarities presented by the birds of these 

 islands, we have only to see how far the same general principles 

 will apply to the insects and land-shells. The butterflies, 

 moths, and hymenoptera, are few in number, and almost all 

 seem to be common European species, whose presence is 

 explained by the same causes as those which have introduced 

 the birds. Beetles, however, are more numerous, and have been 

 better studied, and these present some features of interest. The 

 total number of species yet known is 212, of which 175 are 

 European; but out of these 101 are believed to have been 

 introduced by human agency, leaving seventy-four really 

 indigenous. Twenty-three of these indigenous species are not 



