PLATE XXIX. 



PISIDITTM HIBERNICUM, Westerlund. 



1. External right aspect of a pair 



* t Internal aspect of two pairs 



3. a, b. J ! Lough 



4. Diagrammatic enlargement of the Hinge i Namaddra, 



5. a, b. Anterior and dorsal view of a pair | Co. Cork. 



6. External right aspect of a pair 



PlSIDIlTM MILIUM, Held. 



7. a-j. Internal aspect of five pairs of different ages, from 



Totteridge, Hertfordshire. 



8. a, b. Posterior and dorsal view of a pair from Comber, 



Co. Down. 



9. r t b. of a pair from Criccieth, Carnarvonshire. 



10. a, b. of apposed valves from the Holocene at Gayfield, 



Edinburgh. 



11. a, b. of a pair from Ashridge, Hertfordshire, 



12. a, b. Internal aspect of a pair from Blythburgh, Suffolk. 



13. cr, b. of a pair from Rhosneigr, Anglesey. 



14. , b. of a pair from Button Coldfield, Warwickshire. 



15. , 6. of a pair from Lochmaben, Dumfriesshire. 



16. a, b. of a pair of valves from the Holocene at Newbury, 



Berkshire. 



17. , b. of a pair of valves from the Holocene at Shand 



Street, Tooley Street, London. 



18. , b. = of a pair of valves from the Pleistocene at Swans- 



combe, Kent. 



19. Diagrammatic enlargement of the Hinge. 



20. a-e. External right aspect of five pairs of different ages, 



from Totteridge, Hertfordshire. 



21. of a pair from Blythburgh, Suffolk. 



22. of a pair from Rhosneigr, Anglesey. 



23. -* of a pair from Comber, Co. Down. 



24. of a pair from Ashridge, Hertfordshire. 



25. ..-. - of a pair from Criccieth, Carnarvonshire. 



26. of a pair from Castle Rising, Norfolk. 



27. of a pair from Baguley Pit, Cheshire. 



28. a, b. External aspect of two valves from the Holocene at 



Shand Street, Tooley Street, London. 



29. , b. of two valves from the Holocene at Newbury, 



Berkshire. 



30. a-f --- of six valves from the Holocene at Gayfield, 



Edinburgh. 



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

 shows the amount of magnification. 



