>rous Structure. 4.57 



according to the proportions of one in my possession two feet 

 long, the shell to which it belonged must have been at least twenty 

 feet long. Indeed I have fragments of a fossil shell, apparently 

 belonging to this genus, found near Bath and Oxford*, which 

 upon such a calculation must have formed parts of shells at least 

 120 feet long. I learn from my kind friend Mr. Gideon Mantel], 

 of Lewes, that this species of shell may be traced on the face of 

 some of the chalk cliffs sometimes to four or five feet in diame- 

 ter. They are accompanied in general by the Plagiostuma spi- 

 iiosa, tab. 78. Min, Cone, and some other curious species not 

 before settled. 



That species of this genus of which 1 have chiefly spoken I 

 would distinguish by the specific name Cuvieri, in honour of the 

 extensive abilities of the discerning Cuvier. 



In many places a fibrous secretion of carbonate of lime, much 

 resembling this, sometimes occurs from very thin to many inches 

 thick, spreading in a stratified manner over many acres, which 

 might from the structure be taken for fibrous shell. See Brit. 

 Min. t. 345, middle figure. I have specimens, by the kind at- 

 tention of Miss E. Benett, found at Osmington, the fibres of 

 which are very thin, and five inches long, yet by various speci- 

 mens they may be traced to the form of the cone in cone coral 

 (as it is commonly called), a peculiar crystallization. Brit. 

 Min. t. 149- 



Having said thus much in hopes of assisting and gaining in- 

 formation, I must now add a few words in explanation of the 



* Brie. Min. t. 345, the upper and lower figures, express such fragments : and on 

 the 1 st of June 1 8 1 8, 1 had the pleasure of receiving, by the favour of an intelligent and 

 kind friend, from near Caen in Normandy, two pieces, one with the hinge, and another 

 with the muscular impression, both resembling Ostrea : possibly these may lead, as the 

 former, to a more marked attention and complete discovery. If an oyster, it is en- 

 titled to a name expressing its more extraordinary fibrous distinction. 



drawing, 



