PRE F AC'ti. 



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 



