The geographical distribution of animals, with a study of the relations ...

chap, x.] THE PAL^EARCTIC REGION. 207find 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 theislands, but closely allied to a European species. Of land birdsthere are twenty-two, belonging to twenty-one genera, all European.These genera are Cerchneis, Buteo, Asio, Strix, Turdus,Oriolus, Erithacus, Sylvia, Regulus, Saxicola, Motacilla, Plectrophanes,Fringilla, Pyrrhula, Serinus, Stumus, Picus,Upwpa, Columba, Caccabis, and Coturnix. Besides the bullfinch{Pyrrhula) other species show slight differences from theirEuropean allies, but not such as to render them more thanvarieties. The only truly indigenous mammal is a bat of aEuropean species. Nine butterflies inhabit the Azores ; eightof them are European species, one North American. Of beetles212 have been collected, of which no less than 175 are Europeanspecies; of the remainder, nineteen are found in theCanaries or Madeira, three in South America, while fourteenare peculiar to the islands.Now these facts (for which we are indebted to Mr. Godman'sNatural History of the Azores) are both unexpected and exceedinglyinstructive. In most other cases of remote Oceanicislands, a much larger proportion of the fauna is endemic, orconsists of peculiar species and often of peculiar genera ; as iswell shown by the caseof the Galapagos and Juan Fernandez,both much nearer to a continent and both containing peculiargenera and species of birds. Now we know that the cause andmeaning of this difference is, that in the one case the originalimmigration isvery remote and has never or very rarely beenrepeated, so that under the unchecked influence of new conditionsof life the species have become modified ;in the othercase, either the original immigration has been recent, or if remotehas been so frequently repeated that the new comers have keptup the purity of the stock, and have not allowed time for thenew conditions to produce the effect we are sure they would intime produce if not counteracted. For Mr. Godman tells usthat many of the birds are modified—instancing the gold-crestedwren, blackcap, and rockdove—and he adds, that the modifica-