NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 47 



12. Lower Calder — Canal near Wakefield, H. P. ! ditches near Cold Hiend- 



ley reservoir, March 29, 1868 ! Newton near Wakefield, J.W. ! 

 Cold Hiendley reservoir ! Common throughout the Wakefield 

 district, J.H., 1874 ; Thome's House fish pond, 1882, J.W. ; 

 St. Swithin's Wood dykes, J.W. ; Stanley, J.W. ; Ahofts, 1872, 

 J.W. ; New Miller Dam, J.W. 



13. Airedale — Halton, 187 1 ! common within a dozen miles of Lofthouse, 



Geo. Roberts ; Methley. a few, Dec. 1882, H. L. Oxley ! canal, 

 Calverley! Oulton, J.W. ; Methley, J.W. 



14. Malhamdale — Common in marsh by the side of Malham Tarn, 1,300 



feet above sea level, W. West ! 



15. M^/?a/-/eofa/e— Ditch near Otley, H.S. ; Drygill, 1882, Geo. Roberts; 



stream near Starbotton, one, dead, August 24, 1882, W.D. R. ! 



numerous in roadside ditches at Linton near Grassington, August 7, 



1882, H. T. Soppitt ! Grassington, H. T. Soppitt ; in a small pond 



on the roadside near Pool ! 

 1 8a. Vale of Mowbray — Amongst Equiseta in a pond between Gormire 



and Whitsuncliffe, and in the ditch on the roadside between Thirsk 



and Topclifie, J. H. Davies, Thirsk list, 1855. 

 20. Lower Tees — General in the Lower Tees district, J. W. Watson, 1881 ; 



several waters near Roseberry in Cleveland, C.A., 1879 ; common 



in stells on Coatham marshes near Redcar, and in a pond near 



Acklam, Baker Hudson. 



22. Upper Derwent — Pond near Cayton Bay, associated with Pisidunn 



cinereum ! abundant in a pond south of Scalby Bridge, July i, 

 1882, W.D.R. ! Scarborough, several, R.M.C. ! Flamborough 

 Head, W. C. Hey. 



23. Chalk lyo/o's— Hessle near Hull, J.D.B.! Hessle-road, Hull, J.D.B. ; 



associated with Limnaa glabra and a few L. peregra in a small but 

 deep pond near Leckonfield Moat, in which the vegetation is mainly 

 Ranunculus, ].T).V>., 1881 ; Burlington, J. S.G. ; Filey, J.U.B. ! 

 Bridlington, debris, a quantity, C. T. Musson ! Speeton undercliff, 

 abundant in pools. May 21, 1883 ! Anlaby Road, Hull, J.D.B. 



24. Holderness — Ditch near Hornsea ! Meaux, and New Holland near 



Meaux, May 29, 1882, W.D.R. ! ditch in a field near Wassand, 

 plentiful, J.D.B., 1880 ; Skipsea ! common about Hull : in some 

 parts of Spring Dyke the water is quite brown with their floating 

 shells, J.D.B. ; Figham near Beverley, May 29, 1882, W.D.R. ! 

 abundant at Swinemoor, drift of Beverley Beck, Long-lane and 

 Kitchen-lane, allnear Beverley, J.D.B., 1882; Wansford, L. B. Ross. 



Var. ecarinata Jeff. 



Planorbis spirorbis Mull. , of Continental Authors. 

 This form is considered a distinct species by continental 

 conchologists ; it differs from the type in the absence of any keel 



