44 



priate place, where the principles of the classifi- 

 cation are examined. 



Each class is subdivided into certain geolo- 

 gical divisions, or families of rocks, of greater or 

 less magnitude ; and these are, chiefly, such as 

 have long been received among geologists. The 

 alterations and additions that have been made, 

 are such as appeared either convenient or neces- 

 sary ; but, whatever they may be, the reasons for 

 which they w r ere made are stated, and they are all 

 conformable to the general principles which per- 

 vade the analogous systems that have already ap- 

 peared in the writings of those who have proceeded 

 on a similar plan. 



The nature of these subdivisions is such that 

 they can neither be considered as genera nor 

 species ; terms which, in reality, are much mis- 

 applied to the mineral departments of nature ; as, 

 from their long application to objects admitting 

 of accurate definition, they imply a degree of pre- 

 cision which cannot be found among these inor- 

 ganic substances. Neither can the term family 

 be always correctly applied to these subdivisions ; 



