XU PREFACE. 



versally admitted,, and the want of such a generally 

 received principle is daily experienced by the prac- 

 tical Mineralogist. In the study of extraneous fos- 

 sils, also, no determinate principle for the division 

 into species, has been hitherto established. None, 

 indeed, till now proposed (A:). Hence, in every 

 system of reliquia that has yet appeared, the species 

 are without order and consistency ; formed accord- 

 ing to the caprice or convenience of the writer ; and 

 characterized by every possible affection, of which 

 these bodies are susceptible. 



6. Specific distinctions of reliquia being found- 

 ed only on the organic form, it follows, that their 

 geological and miner alogical affections, with their 

 modal diversities (v. p. 72.) &c. merely charac- 

 terize specimens. 



For the application of this principle the reader 

 is referred to p. 197. 



7. The specific descriptions of reliquia are to 

 he given according to the principles of Botany and 



(k) Cronsted and Bergman's arrangement of extraneous 

 fossils can scarcely be said to have contained a proposal for the 

 establishment of species, as the specific distinctions of the mineral 

 substances, on which the arrangement w as founded, still remained 

 undetermined. 



