[ ^57 i 



1. The true petrifadions are fuch as have 

 the texture and organic parts of the bodies en- 

 tirely filled up with ftony particles, either of a 

 calcareous nature, as is commonly the cafe: or jiinty: 

 and not unfrequently it is marcafiticaL 



2. Preferved only and unaltered, as feemlng to 

 have loft little except the animal gluten. 



3. Others are only bodies incrujiated with fta- 

 ladtite or calcareous matter. And, 



4. Frequently they are only impreflions received 

 ift their foft ftate. 



Order II. Concreta. Slight conglutinations 

 of different kinds of earths. 



The fpecific differences of thefe bodies arife 

 from the nature principally of the componecit 

 parts, whether ochraceous, calcareous, gypfeous, 

 fpatofe, argillaceous, arenaceous, 



Order III. Terr^^:. Foffii fubftances not 

 conglutinated, but ufually in a flightly cohering 

 or pulverized ftate. 



Genera of Fossils, 



I. PETRI FI CAT A. 



IL CONCRETA. 



The generical charadters of thefe two orders arc 

 Very brief, and they occur in the fubfequent ar- 

 rangement of the fpecies. 



Iir/TERRiE. 



