GENERAL VIEW. 35 



the Transactions of the Geological Society, and has 

 thus proved its utility for the purpose of crystallo- 

 graphical description. 



The descriptive system of the Comte de Bournon, 

 with some alterations, will be adopted in this volume, 

 as well as the theory of decrements which constitutes 

 the basis of the Abbe Haiiy's System of Crystallo- 

 graphy. 



