BIVALVE SHELLS. 



Genus 1. 



MYA. 



GENERIC CHARACTER. 



Animal Ascidia. 



Testa bivalvis, hians utpluriniuoi altera extreruitate. 

 Cardo dente, plerisque uno, solido, crasso, patulo, vacuo, (nee inserto 

 testes opposite.) 



Animal an Ascidia. 



Shell of two valves ; in several species open at one end. 

 Hinge, in general, with a single solid, thick, broad tooth, not inserted 

 into the opposite valve. 



GENERAL OBSERVATIONS. 



Bruguiere has separated the My a Pictorum, M. mar- 

 garitifera, and such shells as resemble them, from the 

 Linnaean Myce, and has formed of them a new genus, 

 under the name of TJnio. The difference indeed is 

 obvious between the hinges of the shells just mentioned, 

 and those of the M. truncata, &c. : we shall therefore 

 describe the two kinds under different heads ; namely, 

 shells with teeth not inserted into the opposite valve; and 

 shells with teeth inserted into the opposite valve. There 

 is also a difference in the animal inhabiting the two 

 kinds of shells ; the animals of the 31. truncata, and 

 M. arenaria, bury themselves in the sand, and are, each 

 of them, provided with a long flexible double tube^ 



