EXPLANATION OF THE PLATES 

 Plate 1 



Fig. 1. ElUptio divaricatus. Right valve. Type. 



2. ElUptio divaricatus. Left valve. Type. 



3. Hyria wheatleyi. Right valve. Type. 



4. Succvnea felipponei. Type. 



5. Hyria wheatleyi. Left valve. Type. 



6. Tetraplodon linki. Right valve. Type. 



7. Tetraplodon linki. Left valve. Type. 



8. Odontostomus {Cyclodontina) chaseae. Type. 



9. Ampullaria sitperia. Type. 



10. Odontostomus {Cyclodontina) iheringi. Type. 



Plate 2 

 All figures three-fourths natural size 



Fig. 1. Diplodon {Cyclomya) smithi. Left valve. Type. 



2. Diplodon asuncionis. Left valve. Type. 



3. Anodoutitcs irisans. Right valve. Type. 



4. Nephronaias lempensis. Right valve. Type. 



5. Anodontitcs iri.mns. Left valve. Type. 



6. Nephronaias lempensis. Left valve. Type. 



7. Diplodon (Cyclomya) smithi. Right valve. Type. 

 S. Diplodon asuncionis. Right valve. Type. 



Plate 3 



Fig. 1. Hyria wheatleyi. Dorsal view. Type. 



2. Tetraplodon linki. Dorsal view. Type. 



3. ElUtitio divaricatus. Dorsal view. Type. 



4. Nephronaias lempensis. Dorsal view. Type. 



5. Diplodon asuncionis. Dorsal view. Type. 



ii. Diplodon {Cyclomya) smithi. Dorsal view. Typtv 

 7. Anodontitcs irisans. Dorsal view. Type. 



12 



o 



