334 Dr. FiTTON on the Strata below the Chalk. 



and prepare the mind for the reception of other proofs of that continuity of 

 action^ which has of late been so ably discussed. 



(173.) Fossils. — A systematic list of all the fossils mentioned in the pre- 

 ceding- pages* is given in the Appendix B : and I have connected with it a series 

 of columns, exhibiting at one view the stratigraphic distribution of the several 

 species. My collection is so incomplete, that many of the columns are un- 

 occupied ; and most of them afford very inadequate representations of the 

 facts : but it will be advantageous to keep in view the completion of such a 

 list, whenever sufficient materials shall be obtained to fill it up. The number 

 of specimens collected from any given district or series of strata, depends on 

 so many circumstances purely accidental, — the texture of the matrix, the num- 

 ber of open quarries, the relative skill and activity of collectors, — that the 

 richest collections can very seldom be regarded as fairly representing the 

 fossil contents of the groups from which they are obtained ; and there still 

 are large tracts, in every part of the English series, the fossils of which are un- 

 known. The proportion, therefore, which the species we are acquainted with, 

 bear to the whole number contained in the strata, is so far from being de- 

 termined, that any general reasoning upon this subject at present would be 

 of little value. 



From the imperfect lists of fossils given above, it would seem that even 

 short distances are attended with greater variation in the contents of the 

 strata, than might have been expected ; and that although some species pervade 

 the whole range of the formations in which they are found, others occur in 

 several of the tracts described which have not yet been obtained elsewhere. 



I cannot conclude these pages without expressing my great obligation to 

 Mr. Lonsdale, for his kind and unremitting assistance during their passage 

 through the press ; which has been doubly acceptable, from its having been 

 conferred on me by one of my most valued personal friends. 



W. H. F. 



London, August 16, 1836. 



* It may be proper to mention here, that the whole of the author's collection re- 

 ferred to in the preceding lists, has been presented to the Geological Society, and will 

 be found in their Museum. 



