PLATE XIX. 

 PISIDICM XITIDUAT, Jcnyns. 



1. a, b. External right aspect of two pairs from Swinton, Lancashire. (T. Rogers 



coll.) 

 "2. of a pair from Truro. Cornwall. (0. Boettger.) 



3. of a pair from Sutton Coldfield Park, Warwickshire. 



4. , I. Posterior and dorsal view of a pair from Ten by, Pembrokeshire. 



5. a, 1. of a pair from Lough Fern, Co. Donegal. 



6. rt, b. of a pair from Swinton, Lancashire. (T. Rogers coll.) 



7. a, b. of a pair from the Holocene of the Lea Valley, London. 



8. External right aspect of a pair from Hoe Moor, Hampshire. (" Var. 



lateral-is") 



9. of a pair from Louth, Lincolnshire. 



10. of a pair from Church Close, Mortehoe. Devon. 



11. of a pair from Lough Fern, Co. Donegal. 



12. a, b. of two pairs from Deutschbrod, Bohemia. 



13. of a pair from Teuby, Pembrokeshire. 



14. of a pair from Gt. Gaddesden, Hertfordshire. 



15. a, b. of two pairs from Lochmabcn, Dumfriesshire. 



1 6. Diagrammatic enlargement of the Hinge. 



17. a, b. Internal aspect of a pair from Swinton, Lancashire. (T. Rogers coll.) 



18. a, b. . of a pair from Hoe Moor, Hants. (" Var. lateralis") 



19. a, b. of a pair from Tenby, Pembrokeshire. 



20. a-d. of two pairs from Lochmaben, Dumfriesshire. 



21. , b. of a pair from Lough Fern, Co. Donegal. 



22. rt-c. of a pair and a left valve from Church Close, Mortehoe, Devon. 



23. a-d. of two pairs from Deutschbrod, Bohemia. 



24. a, b. of a pair from Truro, Cornwall. (0. Boettger.) 



25. a, b. of a pair from Louth, Lincolnshire. 



26. a-d. of four valves from the Holocene in Surrey, near Staines. 



26*. o, b. of two valves from the Holocene of the Lea Valley, London. 



27. of a right valve from the Holocene at Newbury, Berks. 



28. a, b. of two valves from the Holocene at Clifton Hampden, Oxfordshire. 



29. , b. of a pair from Sutton Coldfield Park, Warwickshire. 



JK). a-(j. External o,spect of a series of valves showing variation, from the 

 Pleistocene at Swanscombe, Kent. 



31. a, b. of two valves from the Holocene at Clifton Hampden, Oxfordshire. 



32. of a right valve from the Holocene at Newbury, Berks. 



33. a, b. of two valves from the Holocene in Surrey, near Staines. 



34. a-f. Internal aspect of a scries of valves from the Pleistocene at Swanscombe, 



Kent. 



35. , b. of two valves from the Pleistocene at West Wittering, Sussex. 



36. a-d. of four valves from theCromerian (peat) at West Eunton, Norfolk. 



37. ((, b. of a pair from Gt. Gaddesden, Hertfordshire. 



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

 shows the amount of magnification. 



