33 



earth, appearing to approach the nearest to the idea, which was 

 wished to be conveyed, it was almost universally adopted to mark 

 this new order. But as confusion might arise^ from employing the 

 >nme word to describe both the class and the order, it was recom- 

 mended by Sir John Hill, for the sake of precision, to annex to the 

 word fossil, when expressive of the order, the epithet extraneous or 

 adventitious. 



As none of the terms, hitherto enumerated, at all marked the 

 change which had taken place in the nature of the substance, this 

 was proposed to be expressed by adopting the term PETRIFAC- 

 TION. The prevailing practice with writers in mineralogy appears 

 at present to be, either the employment of the last mentioned term; 

 or the annexing one or the other of the adjectives (adventitious or 

 extraneous) to the substantive (FOSSIL,) whilst in the common lan- 

 guage of those most conversant with these substances, the idea is 

 conveyed by the substantive alone. 



The more antiquated, and less significant of these modes of ex- 

 pression, do not demand any farther notice. Those alone, which 

 have been adopted since the discovery of the real nature, and origin 

 of these substances, demand that examination, which a convic- 

 tion of the necessity of establishing certain and determined modes 

 of expression, obliges me, with hesitation and diffidence, to under- 

 take. 



PETRIFACTION*, a word very frequently adopted, is certainly 

 quite unqualified to be admitted, as the general term for these sub- 

 stances ; since it refers, only to a conversion into stone ; whilst the 

 changes, which actually take place, are of various kinds : and, in 

 some instances, as in pyritous fossils, the conversion is into a sub- 

 stance, almost as widely different from stone, as from the matter of 



* Petrificata dicuntur vegetabilium vel animantium corpora, in substantiam fossilium 

 mutata. Gesner. 



VOL I. F 



