Position and Physical Features--Chief Zoological Features of the Azores--Birds--Origin of the Azorean Bird Fauna--Insects of the Azores--Land-Shells of the Azores--The Flora of the Azores--The Dispersal of Seeds--Birds as Seed-Carriers--Facilities for Dispersal of Azorean Plants--Important Deduction from the Peculiarities of the Azorean Fauna and Flora. BERMUDA Position and Physical Features--The Red Clay of Bermuda--Zoology of Bermuda--Birds of Bermuda--Comparison of the Bird Faunas of Bermuda and the Azores--Insects of Bermuda--Land Mollusca--Flora of Bermuda--Concluding Remarks on the Azores and Bermuda. We will commence our investigation into the phenomena presented by oceanic islands, with two groups of the North Atlantic, in which the facts are of a comparatively simple nature and such as to afford us a valuable clue to a solution of the more difficult problems we shall have to deal with further on. The Azores and Bermuda offer great contrasts in physical features, but striking similarities in geographical position. The one is volcanic, the other coralline; but both are surrounded by a wide expanse of ocean of enormous depth, the one being about as far from Europe as the other is from America. Both are situated in the {247} temperate zone, and they differ less than six degrees in latitude, yet the vegetation of the one is wholly temperate, while that of the other is almost tropical. The productions of the one are related to Europe, as those of the other are to America, but they present instructive differences; and both afford evidence of the highest value as to the means of dispersal of various groups of organisms across a wide expanse of ocean. THE AZORES, OR WESTERN ISLANDS.