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G E N U S 13. A R C A. Tab. VII. 



CHARACTER GENERIS 



Animal Tethys ? Telia bivalvis, sequivalvis. Cardo dentibus numerofis, 



acutis, alternis, infertis. 



13th GENUS. ARK 'SHELL. PI. VIL 



CHARACTER OF THE GENUS. 



Is the animal a Tethys ? The fliell bivalve, equiv^alve. The hinge with 

 a number of teeth, fliarp, alternate, inferted all along the rim. 



^3'"^ GENRE. L'ARCHE. PL VIL 



CARACTERE DU GENRE. 



L'animal efl il Tethys ? La coquille bivalve, equivalve. La charnière a 

 nombre de dents, aiguës, alternes, inférées. 



This genus is divided into four families as follow : 



* Margine integerrimo ; natibus recurvatis. 

 ** Margine integro ; natibus inflexis. 

 ■*** Margine crenato ; natibus recurvatis. 

 ■**** Margine crenato ; natibus inflexis. 



* The 



