PLATE III. 

 Ventral aspect of Hinges, drawn by camera lucida, of : 



1. Pisidium amnicum. 



2. - astartoides. 



3. - casertanum. 



4. - pusilium. 



5. - pc>-?onali<m. 



6. - nitidum. 



7. sitbtruncatum. 

 8. 



9. - hensloivanum. 



