PLATE VIII. 



PISIDITTM AMNICUM (Muller). 



1. , 6. Internal aspect of adult pair from the Thames at Hampton 



Wick, Middlesex. 



2. a, b. of " var. nova, Paul.," from St. Canzian, Croatia. 



3. , b. of adult pair from the Coin at West Drayton, 



Middlesex. 



4. a, b. Diagrammatic enlargement of the Hinge. 



5. Internal aspect of adult right valve, from Doubs. 



6. of adult left valve of " var. danubialis" from Vienna. 



7. a-j. of a series of pairs of different ages from the Thames 



at Hampton Wick, Middlesex. 



*** The scale in millimetres under each figure, or series of figures, 

 shows the amount of maguifi cation. 



