South American Naiades PDF Download

Excerpt from South American Naiades, Vol. 8: A Contribution to the Knowledge of the Freshwater Mussels of South America The present paper is intended to give a full account of these investigations. Naturally all accessible material has been included. In many cases only shells without their soft parts were available. This remark refers largely to older and some more recent material preserved in the Carnegie Museum obtained from various sources. The Haseman Collection likewise contains only the hard parts of many species, but on the other hand, other accessions consisted of shells with soft parts, as, for instance, the specimens of Anodontites crispatus from the upper Magdalenadrainage in Colombia, collected by Dr. C. H. Eigenmann, and a collection of a number of species from the La Plata in Argentina, received from Dr. A. Windhausen. In spite of the comparative wealth of material at hand, in some respects our collections are not complete and do not permit the determination of certain questions, chiefly taxonomic. My greatest difficulty has been to properly identify the "species" at hand. The older writers, Spix, Wagner, Lea, D Orbigny, Philippi, Hupe, and others, generally described their species from very insufficient material, and the author to whom we are most indebted for clearing up the taxonomy of the South American Naiades, H. Von Ihering, also was often handicapped by having too scanty material. All previous writers had no clear conception of the range of variation in the various forms, and thus their descriptions generally are those of individuals, often indeed very elaborate and complete, but without proper emphasis laid upon the really important specific characters. Simpson's "Descriptive Catalogue" (1914) did not much improve matters, since he was largely dependent upon the unsatisfactory publications of previous authors. I do not claim, by any means, that my treatment of these shells overcomes all these difficulties; on the contrary, I am in many particulars not at all satisfied with the results obtained. Nevertheless, I claim that the study of the soft parts of a great many forms has furnished a basis for the proper understanding of what the "species" are, and has, at least, furnished a clue to their systematic arrangement, incomplete and fragmentary, it may be, but which probably will prove to be of great value, when the soft parts of all or most of the species are known. The difficulty encountered in recognizing the described forms is sometimes exasperating. We should expect, in cases where exact type-localities are given, and where material from these is at hand, that it would not be very great. 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.