NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 43 



6. Trent — Pond near Sandbeck Park gates, a few, W.D. R. ! 



7. Went Vale — Hemsworth Dam, good specimens, C.A., 1854 ; common 



throughout Ackworth district, fine in Hemsworth reservoir, C.A., 

 1874 ; on the weeds, W. E. Brown ; Askern, H.S. ! Norton, one ! 

 Hessle ! Colonel Vincent's pond, Ackworth, associated with P. 

 nitidus, G. F. Linney ; Nostel, H. Richardson. 



8. Dearne — Canal at Royston ! Bretton Park, common, W.D.R. ! Wors- 



borough, H.C. ! 



10. Colne — Mill-dam, Deighton, J.Wh. ; Iluddersfield, not uncommon in 



the canal and in stagnant ditches, G. H. Parke, 1868. 



11. Upper Calder — Luddenden Valley, J. C, 1875. 



12. Lower Calder — Sandal, G.T. ! Woodkirk, Geo. Roberts ; various places 



round Wakefield, J. H., 1874 ; Wintersett reservoir, W. E. Brown. 



13. Airedale — Roundhay, common in Waterloo Lake ! Mill goit at Adel ! 



common in stream at Meanwood ! Waterloo, H.S. ! stream near 

 Shepherd's pond, Sheepscar ! Swillington ! Halton ! Killingbeck, 

 common ! Thorp Hall pastures, one ! Newsam Green near 

 Woodlesford, common, H.S. ; canal at New Wortley, H.S. ; and 

 at Calverley, H.S. ! ditch beside river at Calverley Bridge ! canal 

 at Saltaire, common, W. West ! Micklethwaite, near Bingley ! 

 Roundhay Grange ! Allerton Ings, scarce ! 



14. Malhamdale—Skipton ! 



16. Nidderdale — Hartwith high and low dams, near Birstwith, and Ripley 



Beck, F. T. Walker ! 



1 7. Wensleydale — Ponds at Staveley ! pond at Grewelthorpe ! pond at 



North Stainley I West Tanfield, several ! Whitfield Gill, near 



Askrigg, one, W.D.R. ! 

 1 8a. Vale of Mowbray — Pond between Kilvington and Feliskirk, J. H. 



Davies, 1855. 

 20. Lower Tees — Ditches near Great Ayton, J. W. Watson ; fine, but not 



abundant, in fish-pond at Kirkleatham near Redcar, B. Hudson. 



22. Upper Derwent — Scarborough Castle Hill, W. C. Hey. 



23. Chalk Wolds — Very fine in a pond close to the precipice of Bempton 



Cliffs, 430 feet alt., W. C. Hey ; Welton Dale, near Brough, J.D.B. ; 

 Londesborough, 1880, J.D.B. 



24. Holderness—'Leven canal, J.D.B. ; Hornsea Mere, J.D.B. ; drift of 



Beverley Beck, moderately plentiful, J.D.B. ; Beverley and Barm- 

 ston Drain, J.D.B. ; Swinemoor, near Beverley, J.D.B. 



Var Draparnaldi (Shepp.). 



Planorbis deflectus Say. 

 Planorbis virens Adams. 

 Planorbis obliquus De Kay. 



Dr. Jeffreys considers Planorbis deflectus of Say as referable 



to this variety : the Planorbis virens Adams, and Planorbis 



