48 THE ELEMENTS 



ance is, the quantity of pearls which 

 they sometimes produce. We are 

 told by Camden, for the value of the 

 pearls produced by the Mya Mar- 

 gratifera, that Sir John Hawkins 

 had a patent for fishing for that shell 

 in the river Irt in Cumberland. 



The French naturalists divide this 

 genus into three distinct genera : 

 Mya, Glycimeris, and Vulsella. 



In Turton's Linne twenty-six species 

 are described; and fourteen have been 

 ascertained to inhabit Great Britain. 



Genus 5th. — SOLEN. Animal an 

 Ascidia ; shell bivalve, oblong, open at 

 both ends ; hinge with a subulate re- 

 flected tooth, often double, and not 

 inserted in the opposite valve. Linn. 

 Syst. 304. Plate 5th, fig. 5th. Razor 

 shell. 



Habitation. The Solens have only 

 been found to inhabit the ocean ; they 

 are generally found, buried about six 

 inches deep, in the sand ; their resi- 



