Excerpt from Morphology and Biology of Some Turbellaria From the Mississippi Basin: With Three Plates Woodworth (1897) and Stringer (1909, 1913) have published descriptions Of five new species from Illinois and Nebraska. Eleven other forms, found also in the eastern states, have been reported from a few localities in Illinois, Neb raska, Michigan, and Wisconsin, but these are all. That some species, at least, are present in great numbers is evident from the various collections for experimental studies. The whole Mississippi valley region with its lakes and almost numberless ponds furnishes conditions in many respects ideal for such types, and their existence will sooner or later be demonstrated. In fact, both Planaria and Rhabdocoelida are of much more common occur rence than is generally supposed and for several reasons are especially valuable for study. First, they are available as living reproducing animals thruout the year. Then, they are good for experimental work since they illustrate a some what primitive phylum, one in which the body structure is very different from that commonly encountered. Well adapted to such studies by their simplicity and great vitality, they have come to be the classic specimens employed both for elementary experiment and for complicated investigation. The free-living method of life, together with the simple fundamental anatomy, when compared with the specialized and much changed condition of the nearly related parasitic worms, shows clearly the variations possible and actually brought about by a different mode Of life. As a whole, the group is of more than ordinary interest. Always considered of no importance economically, their possible relation to other forms has been overlooked, so that only by chance have their habits Of parasitism and voracious feeding been discovered, and there is need Of further investigation along this line. 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.