PLATE XIII. 



PlSlDlTTM CASEKTANTJM (Poll). 



1. a, b. Posterior and dorsal view of a pair from Fitton Hall, 01 



Lancashire. ("Pisidium pusillmn, var. yrandis": T. ] 

 coll.) 



2. rt, b. of a pair from Swinton, Lancashire. (" Pisidium pusillum. 



variety. J. G. Jeff." : T. Rogers coll.) 



3. , b. of a pair from Lagan Canal (2nd lock), Cos. Down and Anl 



4. , 5. of a pair from Scarborough, Yorkshire. 



5. a , b. of a pair from Bassenthwaite, Cumberland. 



(>. , b. of a pair from Lancaster. 



7. a, b. of a pair from the Sebeto, Naples. 



8. a, b. of a pair from Wniana, Eoumania. (*' P. fossarinum, Clcs; 



9. External right aspect of a pair from Manchester. (" P. fon 



C. Pr'r., var. rosea, Scholtz " from 0. Boettger.) 

 iO. of a pair from Swinton, Lancashire. (** P./0n*ma?, var. tit 



[sic]," marked " J. G. Jeff." : T. Rogers coll.) 

 ;i. of a pair from Scarborough, Yorkshire. 



2. of a pair from Swinton, Lancashire. (" P. pusillum, large v 



J. G. Jeff." : T. Rogers coll.) 



3. of a pair from Fitton Hall, Oldham, Lancashire. (" P. put 



var. grandis " : T. Rogers coll.) 



4. of a pair from Bath, Somerset. (" P. fontinale, var. pul 



named by Mr. Jenyns " : T. Rogers coll.) 



5. of a pair from Addington, Surrey. 



6. of a pair from Gateshead, Durham. (" P. cinereum " : T. ] 



coll.) 



.7. a-j. of a series of the " lake form " from Bassenthwaite, Cumbe 



8. External left and right aspect of a pair from the type locality at C* 



Italy. 

 External right aspect of two pairs from Hendon, Middlesex. 



of two pairs from IN~orth Wootton, Norfolk. 



of a pair from Shirwell, Devonshire. 



of a pair from Lancaster. 



of three pairs from Lochmaben, Dumfriesshire. 



Posterior and dorsal view of a pair from Vestre Aker, Christiania 

 External right aspect of a pair from Coolkeeragh, Co. Londonden 



of three pairs from the Lagan Canal, Cos. Down and Autrin 



of four pairs from Annadale, Co. Down. 



of a pair from Sicily. (" Galileja tenebrosa, 0. G. C< 



R. Bellini.) 



of a pair from Vestre Aker, Christiania. 



of a pair from Mt. Majella, Italy. (" P. casertanum, var, 



cularis, Norm." : R. Bellini.) 



of a pair from the Sebeto, Naples. 



of a pair from Wniana, Roumania. ("P. fosscirinum, Cless 



of two pairs from Naples. ("P. mistral*, Phill." : R. Bellii 



- of a right valve from Trancailla, Italy. 



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

 shows the amount of magnification. 



