VI PREFACE. 



The mere bulk of the present volume is far fiom adequately represent- 

 ing the amount of labour and anxiety which has been expended on its 

 priiduction, especially as, excepting some special artistic assistance from 

 my daughter with certain of the more difficult coloured figures, I have had, 

 as before, to depend solely on my own hand for the preparation of the 

 text, and the index thereto, as well as for the one hundred and twenty 

 nature coloured paintings illustrating the chief variations of the different 

 species, in addition to which I have also prepared upwards of three 

 hundred anatomical and other drawings from which the explanatory 

 figures in the text have been engraved. 



Although six years have been occupied in the publication of the volume, 

 this lengthy period has been very fully employed in securing and painting 

 from life many of the illustrations, and in the appropriate arrangement 

 and co-ordination of the mass of information accumulated during the 

 past ij^uarter of a century. 



Though it might appear almost invidious to allude to the help rendered 

 by particular individuals, when so many have contributed by their observa- 

 tions and aid to enhance the value and importance of the Monograph, yet 

 I trust I may without injustice again recall with grateful acknowledgment 

 the ever-willing and priceless help so unselfishly rendered me by my late 

 dear friend Mr. Charles Ashford, of Christchurch, whose matchless 

 anatomical skill and scientific acumen were so pre-eminent, while the 

 accuracy and beauty of his preparations and sketches is evidenced by 

 the anatomical diagrams in the present work, many of which are from his 

 hand, and it is to me a matter of sincere regret that my valued friend 

 did not live to see the results of his long and disinterested labours placed 

 permanently on record. 



To Mr. W. Denison Roebuck, P.L.S., of Leeds, who initiated the modern 

 study of slug's in the British Isles, I have also been placed under deep 

 obligations for placing his extensive knowledge on the subject so freely 

 at my disposal, as well as for his willing aid in any direction in which 

 the work most severely pressed, and it is with gratitude I acknowledge 

 his great and varied help. 



Mr. R. Welch, M.R.I. A., of Belfast, has also on very many occasions 

 rendered me numerous special and valuable services, not only by furnish- 



