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XX. On a Fossil Shell of a fibrous Structure, the Fragments of 

 which occur abundantly in the Chalk Strata and in the Flints 

 accompanying it. By Mr. James Sowerby, F.L.S. $c. 



Read November 1, 1814. 



Having, with many others, experienced the want of sufficient 

 information to discriminate the genera to which certain shells 

 belong, and not being satisfied with what has been done, espe- 

 cially regarding the genera of fossil shells, I am induced to offer 

 the following observations to the Linnean Society, in the hope 

 that some person, who has more leisure, experience and judge- 

 ment than myself, will in the course of time favour us with some 

 further elucidation of so interesting a subject. 



I hope I may be pardoned for the length of the detail which 

 I am about to lay before the Society, because accurate distinc- 

 tions and observations are found to be more than ever necessary 

 in the present discerning age, in which such a multiplicity of 

 subjects necessarily arise to improve science. 



In a memoir on the mineralogical geography of the environs 

 of Paris, under the article " Chalk Formation/' by Messieurs 

 Cuvier and Brongniart, in the Annates du Museum d'Histoire 

 Naturelle, torn. xi. p. 293, there arementioned "some fragments 

 of shells, which from their tabular form and fibrous structure 

 cannot be referred to other than the genus Finna ; but if we 

 were to infer from the thickness of the fragments the size of 

 the individuals to which they must have belonged, we must con- 



vol. xiii. 3 n elude 



