Excerpt from Monography of the Family Unionid , or Naiades of Lamarck, (Fresh Water Bivalve Shells, ) of North America: Illustrated by Figures Drawn on Stone From Nature Dr. Kirtland has made some interesting remarks on the sexes of this family, in which he has proved them to be distinct, in the opinion of many concho logists; and the sex can be ascertained by the form of the shell. Almost every Species has two promi nent varieties of form, one of which is shorter and more ventricose than the other, which is happily ex plained by the observations of the intelligent author of the essay referred to. 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.