THIRD EDITION. Xlll 



these organic remains are contained were 

 but ill understood, until Werner pointed out 

 the mode of investigating them. His in- 

 teresting and important views were circu- 

 lated from Freyberg, by the writings and 

 conversations of his pupils, and have con- 

 tributed materially to the advancement of 

 this branch of Natural History in Germany, 

 France, and also in Great Britain. Pe- 

 trifactions are no longer viewed as objects 

 of mere curiosity, as things isolated and 

 unrelated to the rocks of which the crust 

 of the Earth is composed ; on the contrary, 

 they are now considered as one of the most 

 important features in the strata of all re- 

 gions of the earth. By the regularity 

 and determinate nature of their distribu- 

 tion, they afford characters which assist us 

 in discriminating not only single beds, but 

 also whole formations of rocks ; and in this 

 respect they are highly interesting to the 

 geognostical inquirer. To the geologist this 

 beautiful branch of Natural History opens 



