PLATE XXIV. 



PISIDITJM HENSLOWANUM, Sheppard. 



1. a-f. Internal aspect of a series of valves from the Holocene at 



Blythburgh, Suffolk. 



2. a-l-. of a series of valves of different ages to show 



variation, from the rejectamenta of the Thames 

 at Chertsey Mead, Surrey. 



3. a, b. of a pair from the Wendover Canal, Buckingham- 



shire. 



4. Diagrammatic enlargement of the Hinge. 



5. a, b. Internal aspect of a large pair from Lyngby-Bagsvor So, 



Sealand. 



6. a, 6. of a pair from Button Coldfield, Warwickshire. 



7. , b. of a pair from the lied Bridge Pond, Hampstead 



Heath, London. 



8. a- h. "I of a series of valves of all ages showing variation, 



9. a-i. J from the Pleistocene at Crayford-Erith, Kent. 



10. a, b. of two valves from the Cromerian (peat) at West 



Piunton, Norfolk. 



11. a-j. of a series of valves of different ages showing 



variation, from the Pleistocene at Clacton, Essex 



12. a-j. from the Pleistocene at Swanscombe, Kent, 



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

 shows the amount of magniiicatiou. 



