A HISTORY OF DURHAM 



Planorbis sptrorbis, Mull. 



ctmtortus (Linn.) Local : Ryton Haughs ; 

 near Stockton 



fmtanus (Lightf.). Rather rare : Middleton- 



one-Row ; Stockton 

 Pbyiafmttnalis (Linn.) 



hypnorum (Linn.) 



II. PROSOBRANCHIATA 



Paludestrina stagnalls (Bast.). Mouth of the Tees ; 



Seaton Carew 

 Bithynia tentaculata (Linn.) 

 Valvata pise inalis (Mull.) 

 cristata, Mull. 

 Actcula llneata (Drap.). Rare : Castle Eden Dean 



B. PELECYPODA 



Unto margaritifer (Linn.). In the head waters of 



some streams 

 Anodonta cygntea (Linn.) 

 Sphcerium corneum (Linn.) 



lacustre (Mall.) 



Plsidium amnicum (Mall.). Rare: near Stockton- 

 on-Tees, Jesmond Dean 



piulllum (Gmel.). Besides the typical form the 



variety, by some held to be a distinct 



species, P. obtusale, has been taken near 

 Darlington 

 Plsidium nitidum, Jenyns. Near Darlington 



fontinale (Drap.). In addition to the typical 



form, the variety P. pulchellum, by some 

 held to be a distinct species, is plentiful 



milium (Held.). Brastide, near Durham ; 



Ryton Haughs 



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