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Show 1878.] HEMIPTERA OF ST. HELENA. 451 3. As regards the fauna and part of the flora-land connexion from the north, and European affinities. As regards the peculiar part of the flora-land connexion from the south uniting Africa and America. 4. As regards the marine Mollusca, diffusion by means of the Agulhas current from the south. 5. Affinities of the flora somewhat suggestive of extratropical Southern Africa. Against the first of these theories (special creation) it may be argued that such a method is contrary to, as far as we can judge, the whole scheme of creation, and that, while many things can be urged against it, there is nothing to support such a belief. Against the theories which necessitate the existence in time past of a land communication with Africa or America, or both, all the known facts militate. The non-existence in St. Helena of Amphibia and terrestrial mammals1, the large number of peculiar species, as well as the great depth of the surrounding sea, afford reasons for thinking that it is extremely improbable that the island was ever connected with either of these continents. The other theories will be alluded to in giving m y own. A careful consideration of all the known facts leads m e to believe that two, if not three, epochs in the colonization of the island may be distinguished, and that the great bulk of the inhabitants came from the north, but not by means of a continuity of land. The first of these epochs, or that in which the earliest inhabitants of St. Helena reached the island, occurred possibly early in the last glacial period, but perhaps and (even probably) in Miocene times ; and the reasons for thinking so, as well as for believing that the colonists came from the north, I will now try to prove. In the first place, all the peculiar species belong either to peculiar genera, or to genera which, if they have not yet been found in Miocene formations, are (like the genera which have been found) so widely distributed that it seems more than probable that they were Miocene genera. The nearest relations of the peculiar genera are also of this character. To begin with the terrestial fauna, viz. the Mollusca, the Coleoptera, the Hemiptera, and the Arachnida. The molluscan genera are Succinea (with a peculiar subgenus), Helix, Bulimus, and Achatina-genera which all date from the Eocene, and which are all very widely distributed. The Coleoptera, being more numerous, are not so easily disposed of. Taking M r . Wollaston's estimate of what are aboriginal species, we have 40 genera, of which 25 are peculiar. The remaining 15 genera include 10 actually known as Miocene, 4 of wide distribution and therefore probably Miocene, and 1 which is only known from Madeira in addition to St. Helena. Of the 25 peculiar genera, 21 at least belong to families or subfamilies which are Miocene, and 3 are allied to very widely-spread genera. The Hemiptera are not many in number, nor is our information 1 C. Darwin, ' Origin of Species,' 6th edition, p. 350. |