"Nothing can be unworthy of being investigated by man, which was thought
worthy of being created by God."- BOYLE.

"Divine communications are alike vouchsafed to us by the Volume of Nature,
and the pages of inspiration." - - BACON.

LONDON:

Printed by A. SPOTTISWOOPE,
New-Street-Square.

PREFACE.

THE Introduction to this edition contains, 1st, an explanation of the means which I have used to improve the work; 2dly, an account of the species which I have reason to believe had been, from various causes, erroneously introduced into works of this kind, and the grounds on which they have been here rejected; 3dly, a sketch of the geographical distribution of the species, as compared with the rest of the world, and with different parts of our own country. I fear that this part of the subject, which has been here taken up for the first time, from the poverty of the materials at my disposal, is not so perfect as it should be; but it is to be hoped, that readers living in different parts of the country (now that their observation is directed to the subject) will pay more attention to it, so that in future editions of the work may be carried out in a more complete manner. It should be observed, that the whole value of the lists, and of the table, must depend on the accurate determination of the species, which is of the first importance; while the extent of the list (which appears to be the general pride of the local collector) is of a very secondary consideration. Since this part of the work was printed, Mr. Forbes has presented to the British

it

Association, at Birmingham, his Report on this subject, which (judging from the abstract of it that was read at the meeting, and has since been printed in the Athenæum,) will doubtless contain much additional information. The Introduction also contains, 4thly, an account of the fossil species which formerly inhabited this country; 5thly, the situations generally preferred by different species of shells; 6thly, an outline of the history of the various additions that have been made, from time to time, in this part of our Fauna; and, lastly, a catalogue of the works and papers which treat on British land and fresh-water mollusca, and of the best works on European species.

For the purpose of assisting the young student, or those who study the mere shell, without paying any attention to the animals that form them, an artificial table of the genera has been framed, and to it is appended a definition of the more important and general terms used in the description of shells; some of which have, until lately, been employed in different senses by even celebrated authors. The description of the species is preceded by a general outline of the distribution of molluscous animals; and the genera have been distributed into natural families from characters taken from the consideration of the animal, which alone can be regarded as the proper subject for classification. Every day proves, to the scientific conchologist, that every modification in the structure of the animal impresses its character on the shell, and that the shells thus afford good subsidiary characters for the distinction of groups.