NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 41 



J. W. ; Pontefract, J.W. ; Askern, J. W. ; very abundant at the 

 brick ponds, Ackworth, on Chara, W. E. Brown ! and in a small 

 pond on the road to Bracken common associated with P. nitidis, 

 W. E. Brown. 

 8. Dearne — Bretton Park, J.W. ; several places near Barnsley, J.W. 



11. Upper Calder — Near Hebden Bridge, in the old pits, on the weeds, 



D. Dyson's Manchester List, 1850, p. 70. 



12. Lower Calder — Newton, near Wakefield, J.W. ! Ossett, common, J.H. ; 



Cold Hiendley, common, J.H. ; Wakefield, J.H. ; Stanley, Geo. 

 Roberts ; Outwood, Geo. Roberts ; New Miller Dam, J.W. ; 

 Alverthorpe, J.W. ; Coxley Valley, J.W. ; Batley, J.W. ; Crofton 

 Park fish-pond, J.W. ; Barnsley canal, J.W. ; Altofts, J.W. ; 

 Normanton, J.W. 



13. Airedale — Pond at Temple View, York Road, Leeds, very plentiful ! 



pond. Black Hills, Leeds ! pond near Osmondthorpe Hall, Leeds ! 

 pond in Osmondthorpe Lane, Leeds, formerly common, not found 

 in 1868! pond. Horse Shoe Lane, Leeds, H.S. ! pond at Round- 

 hay Grange ! Calcoates Lane, Leeds, common, H. S. ! pond in lane 

 between Seacroft and Scarcroft, the only species found ! pond near 

 Seacroft Hall, associated with Pisidium fusilluvi and Limncea 

 peregra ! pond, Oak-tree Farm, Harehills-lane, Leeds ! Scholes, 

 near Leeds I pond, Roundhay Limehills ! Oulton, J.W. ; Bingley, 

 J.W^. ; canal, Saltaire, J.W. 



16. Nidderdale — Pannal, J.W. 



17. Wensleydale — West Tanfield ! pond at Grewelthorpe, April, 1880! 



Skelton near Ripon ! 

 i8a. Vale of Mowbray — Vale of Mowbray, W. Grainge, 1859. 



20. Lower Tees — Ditches near Middlesbrough, W.H.B. ; near Middles- 



brough, J. W. Watson ; Coatham Marshes, where it is abundant on 

 Lemna minor in a pond, the usual ridges imperfectly developed, 

 C.A. ; abundant in fish-pond at Kirkleatham, near Redcar, B. 

 Hudson. 



21. Eskdale — On the coast near Whitby, J.W. and G.R. 



22. Upper Derwent — Scarborough, R.M.C. and J.W. 



24. Holderness — Hornsea Mere, J.D.B. ; pond near Springhead, Hull, 

 abundant, 1881, J.D.B. ; ditch bordering Swinemoor near 

 Beverley, J.D.B. 



Var. crista (L.). 

 We have adopted Linne's name c'rishi to distinguish this 

 variety, in preference to the more recent one cristata of 

 Draparnaud. 



3. Vale of York — Askham Bog, W. C. Hey ; Tadcaster, rarer than type, 

 F. G. Binnie. 



