chap, x.] THE PAL^EARCTIC REGION. 207 



find that they are of Palsearctic genera and, with one exception, 

 all of species found either in Europe, North Africa, Madeira, 

 or the Canaries. The exception is a bullfinch peculiar to the 

 islands, but closely allied to a European species. Of land birds 

 there are twenty-two, belonging to twenty-one genera, all Euro- 

 pean. These genera are Cerchneis, Buteo, Asio, Strix, Turdus, 

 Oriolus, Erithacus, Sylvia, Regulus, Saxicola, Motacilla, Plec- 

 trophanes, Fringilla, Pyrrhula, Serinus, Stumus, Picus, 

 Upwpa, Columba, Caccabis, and Coturnix. Besides the bull- 

 finch {Pyrrhula) other species show slight differences from their 

 European allies, but not such as to render them more than 

 varieties. The only truly indigenous mammal is a bat of a 

 European species. Nine butterflies inhabit the Azores ; eight 

 of them are European species, one North American. Of beetles 

 212 have been collected, of which no less than 175 are Euro- 

 pean species; of the remainder, nineteen are found in the 

 Canaries or Madeira, three in South America, while fourteen 

 are peculiar to the islands. 



Now these facts (for which we are indebted to Mr. Godman's 

 Natural History of the Azores) are both unexpected and exceed- 

 ingly instructive. In most other cases of remote Oceanic 

 islands, a much larger proportion of the fauna is endemic, or 

 consists of peculiar species and often of peculiar genera ; as is 

 well shown by the case of the Galapagos and Juan Fernandez, 

 both much nearer to a continent and both containing peculiar 

 genera and species of birds. Now we know that the cause and 

 meaning of this difference is, that in the one case the original 

 immigration is very remote and has never or very rarely been 

 repeated, so that under the unchecked influence of new condi- 

 tions of life the species have become modified ; in the other 

 case, either the original immigration has been recent, or if remote 

 has been so frequently repeated that the new comers have kept 

 up the purity of the stock, and have not allowed time for the 

 new conditions to produce the effect we are sure they would in 

 time produce if not counteracted. For Mr. Godman tells us 

 that many of the birds are modified — instancing the gold-crested 

 wren, blackcap, and rock dove — and he adds, that the modifica- 



