HE completion of another volume, 
dealing with the Aonitidw, Lndo- 
dontidw and [Helicidw, is to me a 
matter of much satisfaction, and 
although its preparation has occu- 
pied a considerable time, this has 
unfortunately been unavoidable, as 
other and inexorable duties inter- 
fered for a period with my active 
prosecution of the work, and as I 
still am entirely dependent on my own personal skill and diligence for 
the whole of the artistic, scientific, and literary work involved in the 
production of the Monograph, a temporary cessation of publication was 
inevitable, as no person was available to fulfil my task who possessed 
the necessary leisure combined with the indispensable scientific attain- 
ments and artistic skill requisite for the maintenance of the standard 
of excellence desired and hitherto maintained. 
The exacting nature of these duties is demonstrated by the fact that 
for the production of the present volume I have had to prepare five 
hundred pages of text, in addition to compiling the Index, and performing 
all the other onerous yet necessary literary labour involved ; the illustra- 
tions in the text, upwards of eight hundred in number, showing the 
structural and other details of shell and animal, were nearly all drawn and 
painted by myself, many of them being original and never previously 
published ; the preparation of the forty-eight coloured and other maps, 
graphically illustrating the British distribution, as well as the complete 
range of each species, with the consideration and decision upon the many 
doubtful points involved also occupied a considerable time ; while the 
painting of the more than two hundred original water-colour drawings 
depicting in natural colours selected examples of the various species 
treated of, occupied much of my available leisure, which was further 
encroached upon by the incessant supervision necessary to ensure their 
faithful reproduction and by the insistent demands of an extensive and 
at times very harassing correspondeuce. 
