36 Geological Arrangemeiit of British Fossil Shells, 



MULTILOCULAR UNIVALVES — continued. 



■* We are thus made acquainted with the geognostical distri- 

 bution of about thirteen hundred fossil Testacea; and from 

 the caution employed in the foregoing classification, these are 

 probably considerably short of the actual number known to 

 collectors, without including the varieties, or the many unpub- 

 lished species, perhaps even several genera, remaining in the 

 cabinets of individuals. Had Mr. Farcy's suggestion been 

 adopted, of naming the shells in each stratum separately, and 

 of treating them as distinct species or varieties, as often as they 

 occurred in successive beds, their amount would, by this time, 

 have been so great as to counterbalance any supposed useful 

 result. Even now, the opinion is not wholly abandoned by 

 some of our best naturalists, that distinct fossil species are 

 peculiar to each formation. 



But it has been held, and apparently with some reason, 

 that too much stress is laid on insignificant distinctions, 

 whereby an unnecessary increase of species has arisen, pro- 

 ductive of no slight embarrassment to the student, and of little 

 adequate benefit to the practical geologist. 



It results from the foregoing investigation, that the follow- 

 ing series of fossil shells are known to English naturalists : — 



Simple univalves 58 genera, which comprise 401 species. 



Simple bivalves 62 - - - 583 ■ 



Complicated bivalves 3 - - - 51 



Multilocular univalves 12 - - - 230 



J35 



1265 



