PREFACE. 
The present work was undertaken with the object of placing in the 
hands of those interested in the conchology of this country a treatise 
dealing comprehensively and in detail with the many points of interest 
presented by our native species of land and freshwater mollusca. 
Hitherto, with few exceptions, the published works have viewed 
this subject from very restricted standpoints, and have not attempted 
to convey any detailed information of the intricate and marvellous 
organization of the mollusca, nor to give any really comprehensive 
survey of the subject or discuss the bearings their study could have 
upon the larger problems that are yet far from solution by the scien- 
tific world. 
Very many years have been devoted to the study of the subject in 
its various aspects and to the accumulation of information, in which 
labours I had for some years the co-operation of my late dear friend, 
Mr. Charles Ashford, to whom much of the anatomical detail given 
in the work is due. Mr. W. Denison Roebuck, F.L.S., was also for a 
lengthened period closely associated with me in its preparation and 
still practically evinces in many helpful ways his deep interest in its 
success, and it is in grateful recognition of the generous assistance I 
have received that I associate their names with my own upon the 
title-page. 
The Council of the Conchological Society have practically demon- 
strated their lively interest in my work by kindly permitting me to 
retain in my own possession a considerable part of the society’s library, 
a favour which has been of the greatest assistance to me ; while Mr. 
W. E. Hoyle, M.A., of the Manchester Museum, has laid me under 
heavy obligation by procuring me the opportunity of examining many 
scarce books, which otherwise I should have had a difficulty in obtain- 
ing. Prof. Paul Pelseneer, of Gand, has also given me valuable aid 
