OSTREA. 



TESTA foliacea^ irregularis^ inasquivalvis; umbo- 

 nibus subdivaricatis^ aetate inaequalissimis. Valva 

 ZTj/mormajor^ concava^adhaerens; superior minor, 



^ planiuscula. Cardo edentulus. Ligarnentum semi- 

 intenium, disco subtrigono tripartite in utraque 

 valva^ affixum. Impressiones 7nusculares in utra- 

 que valva duas^ altera magna^ suborbicularis^ 

 subcentralis ; altera minutissima^ infra cardinem 

 posita. 



The Genus Ostrea, as constituted by Linne, comprehended 

 shells of such diversity of character, that it could not pos- 

 sibly remain entire ; and yet, though many perceived the 

 inconvenience of associating regular, sometimes equivalve 

 shells, such as the Pectines and JPlagiostomata, shells attached 

 by a byssus, such as the Mallei and the Pedum; shells cha- 

 racterized by so singular a longitudinally sulcated hinge as 

 the Perna^ together with irregular and inequivalve shells, 

 such as the true Ostrece^ which are withal attached by the 

 outer part of one valve ; Bruguiere seems to have been the 

 first who attempted to distinguish and characterize the va- 

 rious Genera thus confounded under the common term of 

 Ostrea. But Lamarck, though highly approving the judi- 

 cious and convenient purification to which Bruguiere had 

 subjected the Linnsean Ostrea^ still thought the work in- 

 complete ; and, therefore, in order to reduce the Genus to 

 its proper limits, he separated from it the Vulsellce^ the 

 Podopsides and the Gri/phcece : the characters, however, by 

 which he would distinguish this last mentioned Genus from 

 Ostrea, do not appear to us sufficiently decisive to warrant 

 its separation, wherefore we have not adopted his Genus 



