Excerpt from A Guide to the Study of Fresh-Water Biology: With Special Reference to Aquatic Insects and Other Invertebrate Animals and Phyto-Plancton The plan and purpose of this little book in this its fourth re vision are the same as in the earlier ones: to facilitate the recog nition of freshwater organisms in the field and in the laboratory. It offers for the purpose keys and tables and figures illustrating genera. Only things commonly found in fresh waters are in cluded. Inhabitants of Salt and alkaline waters and of caves are omitted. Vertebrate animals and vascular plants are also omitted because they are better known, and because aids to their recognition are commonly available. The larger inverte brates are more fully treated than are the microscopic ones. Genera and not species are illustrated; and generic names are applied in an inclusive sense to groups of species that a beginnef may be able to recognize by external differences. T 0 provide him With a tool that he can use has been out aim, and we trust that that will explain our disregard of some of the much sub divided genera of systematic specialists.

The keys have been expanded to include genera whose immature aquatic stages were formerly unknown. 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.