PREFACE TO THE SECOND EDITION. A FEW months only having elapsed since the publication of the First Edition, little more has been accomplished in the present than the addition of such information as has been published in the interval, or which the personal observations of the Author have enabled him to present. Attempts have indeed been made to purify the lists of Organic Remains, not only by rejecting the names of fossils which were decidedly synonymous with others retained, but also by omitting the names of such exuviæ as, in all probability were erroneously supposed to have been discovered in the rocks and localities enumerated. Considerable additions have likewise been made to these catalogues, but chiefly on the authority of Deshayes, Goldfuss, Munster, and others, whose accuracy in this branch of geological research is well known and generally acknowledged. The lists in question still, however, demand severe examination, and it will probably require much time and frequent comparisons of specimens themselves with each other before they assume that character which is so desirable. While availing himself of these and similar catalogues, the student should be careful to recollect, that however great and valuable the aid of Zoology and Botany may be in geological investigations, Physics and Chemistry are of still greater importance; inasmuch as the former can only be employed with advantage in explanation of a portion of the phænomena observed, while the latter are available to a very great extent in explanation of the whole. |