PLATE XXI. 

 PISIDIUM PUSILLCM, (Gmelin) Jenyns. 



External aspect of a series of pairs from Bracebridge, Warwickshire 



of a pair from the Botanical Gardens, Naples. 



of a pair from Button Coldfield Park, Warwickshire. 



Posterior and dorsal view of a pair from Bracebridge, Warwickshire. 



of a pair from Kilcorrig, Lisburn, Co. Antrim. 



of a pair from Woodburn Dam, Co. Antrim. 



of a pair from Walworth Wood, Co. Londonderry. 



. of a pair from Comber, Co. Down. 



of a pair from the Holocene at Magheragera, Co. Fermanagh. 



External aspect of three right valves from the Holocene at Westb 



on-Severn, Gloucestershire. 



right aspect of a series of six pairs from Woodburn Dam, Co. Ant 



of a series of four pairs from the Holocene of the Lea Va! 



London. 

 of a pair from Tenby, Pembrokeshire. 



of a pair from Comber, Co. Down. 



- of a pair from Walworth Wood, Co. Londondeny. 



of a pair from the River Po, Italy. 



External aspect of a series of valves showing variation, from the Pie 



cene at Swanscombe, Kent. 

 External right aspect of two pairs from Magheragera, Co. Fermana' 



of a pair from llhosneigr, Anglesey. 



of a pair from Kilcorrig, Lisburn, Co. Antrim. 



Diagrammatic enlargement of the Hinge. 



Internal aspect of four valves from the Holocene at Newbury, Berks 



of five valves from the Holocene at Westbury- on-Severn, Glouce* 



shire. 



of five pairs from Woodburn Dam, Co. Antrim. 



of a series of pairs from Bracebridge, Warwickshire. 



of a pair from Baling, Middlesex. 



of four valves from the rejectamenta of the Thames at Choi 



Mead, Surrey. 



of a series of valves from the Holocene of the Lea Valley, Lom 



of two pairs from the Botanical Gardens at Naples. 



of a pair from Kilcorrig, Lisburn, Co. Antrim. 



of four pairs from Magheragera, Co. Fermanagh. 



of a series of valves from the Pleistocene at SAvanscombe, Ken 



of a pair from Tenby, Pembrokeshire. 



of a pair from the Liiver Po, Italy. 



of an abnormal pair from Walworth Wood, Co. Londonderry. 



of a pair from Willenhall, Scaffordshire. 



of two valves from the Cromerian (peat) at West Runton, Nor 



of a pair from Comber, Co. Down. 



of a pair from Walworth Wood, Co. Londonderry. 



- of a pair from Sutton Coldfield Park, Warwickshire. 



of two valves from the Pleistocene at West Wittering, Sussex, 



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

 shows the amount of magnification. 



