INTRODUCTION. xi 
of the Voluta papalis with the Voluta turbinella, 
and of the Buccinum maculatum with the Buecimum 
patulum. How far these objections may be tenable it 
is not our purpose to enquire, being ourselves per- 
suaded that the Linneean system, though capable of 
considerable improvement, presents the most simple 
and concise method of aiding the investigation of this 
branch of natural history. 
The striking dissimilarity of the species in some of 
the genera is certainly an obstacle to the attainment of 
the science; we have, therefore, with a view to facili- 
tate its acquirement, and at the same time not materi- 
ally to depart from the system we have adopted, formed 
divisions of the genera, when any marked dissimilarity 
was observable in the species. And if any of the di- 
visions retained one leading character throughout, to- 
gether with some other characters only partially, we 
have again divided it into families, distinguished by 
those variations. It is possible that the characters of 
many of the divisions will be deemed sufficiently dis- 
tinct to allow of their being formed into additional ge- 
nera, without departing from the original system. 
We have been indebted to other writers on Concho- 
logy for the addition of many new species, and parti- 
cularly to Mr. Dillwyn’s valuable Catalogue of Recent 
Shells. 
Those species which were not found described or 
figured in the works of any author to which we had 
access, are distinguished by an asterisk ; we have also 
named them, considering them to be new species; 
and have endeavoured in the catalogue, to place each 
