Excerpt from New Fresh Water Shells of the United States: With Coloured Illustrations, and a Monograph of the Genus Anculotus of Say; Also a Synopsis of the American Naiades Atlantic rivers form a striking contrast; and it has been a desideratum to discover where the line of demarcation has been drawn by nature in the south ern states, between these two distinct races of shells, and to fix with certainty the geographical limits of the different species. The latter can only be effected by years of patient observation; but by contributing such facts connected with the subject as may come under our notice, we prepare the way for those who may in future pursue the interesting inquiry with more energy and zeal. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This 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.