clude such Geological treatises as contained any information on the structure or distribution of organic remains. But this definition embraced, in fact, nearly every existing geological work, and the labour of examining all such writings to ascertain whether they did or did not contain palæontological matter would have been so great, that it was thought better to extend the limits a little wider so as to include all works on descriptive Geology, whether they referred to organic or to inorganic phænomena.

The first portion of the work contains a list, arranged geographically, of all the known periodical or miscellaneous publications which contain treatises on Zoology or Geology. As however it was in many cases impossible to make a personal examination of all such works, on account of their extreme rarity and limited circulation, it is probable that some of them may not in fact contain matter relevant to our purpose. This seems to be especially the case with the periodicals of France and Italy, enumerated hereafter, many of which appear from their titles to be either of a popular nature, or to be remotely connected with our subject-matter. We have however preferred to err on the side of excess rather than of defect, especially as it may interest the student in other branches of science, to find here recorded the titles of many valuable periodicals whose existence was previously unknown to him. Nor must it be supposed that some Journals, whose titles have no apparent reference to Zoology or Geology, are here inserted without good reason. Many a valuable fact relating to those subjects lies buried in periodicals specially devoted to Chemistry, Meteorology and other physical sciences, and in the majority of instances the compilers have themselves ascertained such to be the case before they ventured to insert a title into their list.

Under Periodical Works are included all serial publica

tions which contain scientific treatises by a variety of hands, such as Transactions of Societies, Journals, Magazines and Encyclopædias. The several treatises of which these periodicals consist, as far as they relate to our subject-matter, are registered alphabetically under the author's name in the second part of the work. This vast undertaking can at present be only partially executed, from the difficulty before alluded to, of obtaining access to all the periodicals enumerated in the first part. So far however as the compilers have been able to perform this part of their project they have done it conscientiously, taking such periodicals as were within their reach, and faithfully extracting the titles of the memoirs which they contain. The titles of all detached and independent works are also inserted in the alphabetical series, so that under the name of each author will be found a complete list of all his writings in these departments of natural history.

As already stated, this compilation is professedly limited to scientific Zoology and Geology, yet it must be admitted that M. Agassiz has inserted, rather too indiscriminately in my opinion, many titles of works which are only remotely connected with those subjects. Had I been the sole compiler instead of the editor of the work, I should, for the sake of rendering it less bulky, have excluded all merely popular and elementary essays, all treatises on Human and Morbid Anatomy, on Ethnography, on Domestication of Animals and the Veterinary Art, on pure Mineralogy and Crystallography, on Mining and Metallurgy, and all popular Voyages and Travels. Too many of such works have however crept into the Catalogue, and I, as editor, did not, except occasionally, feel justified in excluding them. To have erased a work from the list merely because its title appeared irrelevant to our especial subjects would have been highly improper, and to have consulted the original work in all doubtful cases would not only

have been most difficult and laborious, but with regard to many rare and inaccessible publications it would have been impossible. The list furnished by M. Agassiz is therefore substantially produced here, but it has undergone a great amount of careful revision and correction. Several thousand additional titles, selected with great care, have also been added, either by myself or under my immediate inspection. These are principally extracted from British scientific periodicals, with whose contents continental naturalists are too imperfectly acquainted. Many of these titles had been already extracted at second-hand by M. Agassiz from French and German journals where they are translated, and the works of many British writers consequently appeared in a foreign dress. In such cases the original English title has been substituted, and a reference made to the foreign work where the translation appears. In some instances however I have not had an opportunity of verifying such titles with the originals, and they consequently still remain in the list in their exotic form.

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In the case of very short or unimportant communications, a certain amount of discretionary power was indispensable. Our popular " Magazines" of Natural History teem with trifling notices, often anonymous, sometimes brief and indefinite, sometimes wordy and inflated, but which do not contain a single fact of scientific importance. To have recorded all such in our list would have added bulk but not value, and they have therefore been in general omitted. But I have always endeavoured to render due justice to every properly authenticated statement, however brief, of a new or important observation in Zoology or Geology.

Wherever it has been practicable, the lists of each author's writings have been forwarded to him for correction before sending them to the press, and the works of living British

naturalists have thus been accurately registered up to the time of publication.

I am fully prepared to admit that the Catalogue would have been rendered more useful if the works of each author had been chronologically arranged. To a certain extent this has been done; but the mere alphabetical arrangement of such a mass of authors' names was no slight undertaking, and to have cut up and classified each book-title in the order of time would have involved an amount of labour, both mechanical and critical, which it was impossible to spare for such an object. Those therefore who consult this work must be content to find here a full list of the zoo-geo-logical writings of each author, but must not expect any systematic arrangement of those writings, either as to date or subject.

It will be seen that in many instances I have been unable to ascertain the Christian names of the authors recorded in the alphabetical list. This is owing to the singular practice, followed by many persons on the continent of Europe, of signing their surnames only, omitting both the Christian name and its initials. I have never been able to discover the motive for a custom so productive of inconvenience and confusion.

The Council of the RAY SOCIETY propose, when this publication is completed, to print in a Supplement all the additional titles of books or memoirs on Zoology or Geology which have been inadvertently omitted during its progress. There still remain many periodical works, both British and foreign, whose contents have never been looked at with a view to this publication; and of those which have been so consulted, the later volumes have in some cases escaped notice. To render the remaining volumes of the Bibliographia, and its proposed Supplement, as complete as possible, the Council earnestly request the cooperation of the Members of

the Ray Society and of the public. Any person who has access to periodical works, whether British or foreign, which appear to have been unnoticed by the compilers of the present Catalogue, will confer a boon by extracting the titles of the zoological and geological papers which they contain, referring to the volume and page of the original work, in the form adopted in this volume. The titles of such Books also as have been omitted in our list, or have been published subsequently, especially those of rare provincial and otherwise inaccessible tracts and pamphlets on Zoology or Geology, will be exceedingly acceptable. All such titles should be written on one side of the paper only, and may be addressed to the Secretary, Dr. E. Lankester, 22 Old Burlington Street, London.

I wish it had been in my power to have given an exact list of those periodicals, the titles of whose contents have been wholly or partly extracted into this work, so that those who are disposed to aid in the above object might at once see whether any given periodical had already been made use of or not. Unfortunately M. Agassiz omitted to keep such a list; and to enumerate those which have been consulted by myself would have only partially remedied this defect. By referring however to a few of the individual titles, as entered in this volume, it will easily be seen whether the work in which they are contained has been systematically consulted or not; and the List of the Abbreviations employed will also assist this object.

A person who was willing to devote his life to compilation might no doubt have made this work more convenient for some purposes by arranging it as a classed instead of an alphabetical catalogue. Such a task was not, however, practicable in the present case, but every one may to a certain extent make it into a classed catalogue for himself, by attaching