Transcriber's note: A few typographical errors have been corrected: they are listed at the end of the text. * * * * * [Illustration] 1. _Spondylus Americanus. (Young.)_ 2. _Nautilus pompilius. (Young.)_ _G. B. S. Jun^r. fecit._ * * * * * A CONCHOLOGICAL MANUAL. BY G. B. SOWERBY, JUN. ILLUSTRATED BY UPWARDS OF SIX HUNDRED AND SIXTY FIGURES * * * * * SECOND EDITION. CONSIDERABLY ENLARGED AND IMPROVED. * * * * * LONDON: HENRY G. BOHN, YORK STREET, COVENT GARDEN. MDCCCXLII. * * * * * PREFACE TO THE FIRST EDITION. It may be necessary in introducing this little volume, to state, that it is strictly conchological, and that it is compiled for the use not only of those who wish to acquire an elementary acquaintance with the subject, but also of authors and others, who, desirous of extending their knowledge and pursuing their researches, require a book of reference, containing a general outline of what has been done by those who have trodden the same path before them. It has been thought advisable, for general convenience, to arrange the principal part of the information in alphabetical order: adding tables of the systems of Lamarck and De Blainville, to facilitate the systematic pursuit of the science. Persons of the class first alluded to, will find great assistance in the explanation of technical words, their application being further illustrated, in most cases, by a reference to the figures; and, although they might have been multiplied, it is trusted that enough are given for every useful purpose. The definition of the Classes, Orders, Families, and Genera, in the system of De Blainville, and a tabular view, are presented for the use of those who prefer it, or who wish to compare it with that of Lamarck. In the explanation of the figures, will be found a systematic arrangement of shells, according to Lamarck, including the names of genera established or proposed since the publication of his system. The descriptions of established genera have been rendered as concise and clear as possible. It is hoped that no essential characters are omitted, and that those living authors, whose proposed generic distinctions have been passed over in a few words, will not have to complain of want of justice in the attempt to interpret their meaning. In most cases the generic name will be found accompanied by its derivation. This has been done, in the hope of assisting the memory by associating the meaning of a term with some peculiarity in the thing described. At the end of each description of a genus, some general observations occur, pointing out the principal character which distinguishes it from others, to which it is nearly allied; and also stating the geographical or geological distribution and habits of the animal.