402 PEARCE AND MAYFIELD : MOLLUSCA OF EAST NORFOLK. 



Horsey Mere, and Heigham Sounds (S.S.P.) ; in the River 

 Wensum at Heigham and Hellesdon (A.M.). 

 Var. pallida Pascal. With type at Heigham (A.M.). 

 Var. trifasciata Colb. Heigham (A.M.). 



Viviparus contectus (Millet). River Pure at Acle, Horn- 

 ing, Wroxham, also at Bramerton, Surlingham, Brundall, 

 in the River Yare (S.S.P.) ; ditches in the Wensum Valley 

 at Heigham, Hellesdon, and Costessey, ditches at Colney 

 and Thorpe (A.M.). 



V. viviparus (L.). As abundant as the preceding species, 

 and generally taken with it. Brundall, Bramerton, Sur- 

 lingham, in the Yare ; at Wroxham and Horning Ferry, in 

 the Bure (S.S.P.) ; Heigham, Hellesdon, and Postwick 

 (A.M.). 



Bythinia tentaculata (L.). Most abundant in all the 

 streams and ditches of the Yare, Bure, and Wensum 

 Valleys (S.S.P. and A.M.). 



B. leachii (Shepp.). Ditch at Horning Ferry, Acle, by New 

 Cut at Reedham, Whitlingham, and in the Taas tributary 

 at Stoke Holy Cross (S.S.P.) ; Colney, Heigham, Thorpe 

 (A.M.). 

 Var. elongata Jeff. Surlingham Ferry (S.S.P.). 



Valvata piscinalis (Miill. ). Very plentiful in ditches, 

 streams, and broads of the Yare and the Bure rivers 

 (S.S.P.); at Colney, Costessey, especially abundant at 

 Thorpe (A.M.). 



V. cristata Miill. Plentiful. Ditches at Horning Ferry, 

 Postwick Grove, ditch at Whitlingham Marsh (S.S.P.); 

 Arminghall, Thorpe, Colney, etc. (A.M.). 



Unio pictorum L. In the River Yare abundant, Postwick, 

 Whitlingham, Trowse, Surlingham, Brundall ; in the Bure 

 valley it is common at Wroxham and Acles Bridges, also 

 in Thurne Stream and Heigham Sounds (S.S.P.) ; River 

 Wensum at Heigham and Hellesdon (A.M.). 



J.C., vii., July 1894. 



