EXPLANATIONS TO THE PLATES. 
PAGE 
Title-page. 
Snail and Shell of Helix aspersa . . .112 
Plate I. to face page 24. 
FIG. 
1. Anodon cygneus .30 
Plate II. to face page 30. 
2. TJnio tumidus , the valves separated to show the 
hinge, &c. 
. 
. 26 
3. TJnio pidorum . 
. 
10, 26 
4. Anodon cygneus , var. 
anatinus . 
. 31 
5. Valvata piscinalis 
. 
. 58 
6. „ cristata 
. 
. 59 
7. Hydrobia similis 
. 
. 64 
8. Assiminia Gray ana 
. 
. 63 
Plate III 
’. to face page 34. 
9. Cyclas pisidioides 
. 35 
10. „ ovalis 
. 36 
11 . Pisidium amnicum 
. 38 
12. Cyclas lacustris . 
. 36 
13. Bithinia Leachii 
. 57 
14. „ tentaculata 
. 56 
15. Unio margaritiferus 
Q 
. 26 
