PLATE VIII. 

 PISIDIUM AMNICUM (Miiller). 



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



Wick, Middlesex. 



2. rt, I. of " var. nova, Paul.," from St. Canzian, Croatia. 



3. <7, b. of adult pair from the Coin at West Dray ton, 



Middlesex. 



4. , 6. Diagrammatic enlargement of the Hinge. 



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



0. 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 millimetre^ under each figure, or series of figures, 

 shows the amount of magnification. 



