PALAEONTOLOGY. 125 



will lead to a thorough and philosophic description of 

 the rocks composing the area upon which he is engaged, 

 and will enable him to understand aright its physical, 

 stratigraphical, and palseontological peculiarities. 



I. NATURE OF FOSSIL KEMAINS. 



Fossils have been denned as " organic remains buried 

 in the earth," the operations of natural causes being of 

 course understood, and no limitation as to the subsequent 

 lapse of time nor any reference to their present state 

 being allowed to enter into the definition ; since, as Mr. 

 Jukes has well observed, "any accumulation of shells, or 

 bones, or plants, which could be said to be buried in 

 the earth by any other than human agency, even if that 

 burial took place last year, would be well worth the at- 

 tention of the palaeontologist." Our first enquiry must 

 have reference to the nature of these remains, the par- 

 ticular organic forms which are likely to occur fossil, 

 and the various states of preservation in which they are 

 severally and collectively found. 



It is not every buried organism that leaves behind it 

 a permanent record of its previous existence, and only 

 those animals which contain a bony skeleton, or are en- 

 closed in a hard shell or test, can as a rule become 

 definitely fossilized; while plants and those animals 

 which do not possess any such hard structures are rarely 

 found, except in the form of impressions or tracks on the 

 surface of beds the peculiar mineralization which 

 woody matter undergoes being of course an exception to 

 this statement. 



Again, the nature of the remains or records of past 



