CHAP. XII THE AZORES 253 



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 accounting 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 num- 

 ber, 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 found in 

 any of the other Atlantic islands, showing that they have 

 been introduced directly from Europe by causes which 

 have acted more powerfully here than farther south. 

 Besides these there are thirty-six species not found in 

 Europe, of which nineteen are natives of Madeira or the 

 Canaries, three are American, and fourteen are altogether 

 peculiar to the Azores. These latter are mostly allied to 

 species found in Europe or in the other Atlantic islands, 

 while one is allied to an American species, and two are so 

 distinct as to constitute new genera. The following list of 

 these peculiar species will be interesting : — 



CARABIDiE. 



Andwmenus a])tinoides ...Allied to a species from the Canaries. 

 Bemhidium hesioerus Allied to the European B. Icetum. 



Dytiscid^. 

 Agahus godmanni Allied to the European A. dispar. 



COLYDIID^. 



Tarphius woUastoni A genus almost peculiar to the Atlantic islands. 



