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Excerpt from Proceedings: An Academy of Natural Sciences of Philadelphia, 1879The most surprising feature in the geographical distribution of this species is its occurrence in three distinct groups of islands. It is found, though Sparingly, in nearly every valley in Tahiti, which is over 300 miles from its metropolis. I also obtained it at Mangaia, one of the Cook's or Hervey Islands, 400 miles west of Rurutu.Had it only been detected in one or two valleys in Tahiti, its introduction could have been attributed to human agency. But when we consider its wide diffusion we can only account for its presence either by a separate creation of the same species in three groups of islands, or speculate on its distribution in some remote period, when the three groups formed a single large island, or part of a continent.After a careful comparison of many examples from the three groups of islands, I cannot detect the slightest variation. Shells from the same locality vary slightly in the length of the spire, in size and thickness.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.