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Show 1892.] LAND-SHELLS OF ST. HELEVA. 259 collection, and for the careful notes regarding localities which accompany the specimens. The most complete account of the terrestrial fauna ' of St. Helena hitherto published is that given by Mr. Wollaston in his work 'Testacea Atlantica,' published in 1878. He there enumerates 29 species of Land-Shells, of which 9 at least must be regarded as introductions since the discovery of the island 390 years ago. Some of these species-for example, Limax gagates, Vitrea cellaria, V. alliaria, Helix pulchella, H. aspersa, and Pupa umbilicata ( - helen-ensis, Pfr.)-were doubtless introduced along with European shrubs and plants. Patula pmsilla probably was imported from Madeira, the Canary Islands, or the Azores, where it is very abundant; and the two remaining species, Stenogyra compressilabris and Acicula veru, upon which some remarks will be made at the end of this paper, are evidently West-Indian forms. With regard to the twenty indigenous species mentioned by Mr. Wollastou, some, in my opinion, are merely varieties and not specifically distinct. After a careful study of all the forms, including the eleven new species now described, the total number of indigenous species may be estimated at twenty-seven. Of these, seven are living on the island at the present time, eighteen have become extinct since the destruction of the primaeval forests, and two are found both recent and semi-fossil. A great deal has been written upon the relationship of the fauna of St. Helena with regard to other parts of the globe, and an interesting resume of this subject is given by Mr. Wallace in his work ' Island Life,' pp. 281-297. Professor Forbes many years ago, from a study of the Mollusca, hazarded the theory of a possible ancient connection of St. Helena with South America. This view, however, was vigorously rejected by Wollaston, Jeffreys, and others, and, considering the present isolated position of the island, the actual enormous depth of the surrounding ocean, and other cogent reasons 2, this theory certainly does appear unsupportable. There is, however, a greater resemblance between the shell-fauna of the two localities than was recognized either by Forbes or Wollaston ; and the occurrence of a species, discovered since they investigated this subject, and more resembling a group (Tomigerus) which is exclusively Brazilian in distribution than any other, together with the reasons which influenced Forbes, would seem to indicate that country as the probable source whence some of the indigenous but now extinct species, or their ancestors, originated. How they were transmitted is a hopeless problem to solve, and although drift-wood, carried by oceanic currents, is doubtless answerable for a good deal in the way of distribution, the subject must apparently ever remain one of mere speculation. It has been stated by Mr. Wollaston that the large Bulimus auris-vulpina is represented in the Solomon Islands and New Zealand by 1 No freshwater forms have as yet been discovered. 2 Neither the flora of St. Helena nor the insect-fauna suggests particularly a South-American relationship or origin. |