X 
PREFACE. 
Conchology. That some difficulties do 
exist in this branch of study, will readily 
be allowed ; but at the same time we cannot 
but regret, that the very acknowledgment 
of their existence has extremely increased 
their number : for a supposition seems to 
have been universally indulged, that con- 
chology lay open as a common field for 
speculation, in which every individual, 
whether qualified or not, was at liberty to 
range, and exercise, without restraint, his 
genius for invention. The consequence 
has been, that scarcely two writers on the 
subject have agreed in their opinions, and 
that this general want of concurrence has 
aggravated the evils which each endea- 
voured to remove. 
It is easier to refute error than to estab- 
lish truth : thus, the several writers who 
