NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 49 



4. Number — Howden ! and pond near Howden station I Carlton pond nr. 



Snaith, several, June 17th, 1882, W.D.R. ! canal at Burton Hall ! 

 Selby Cut ! ditch alongside Selby Cut ! ditch, Ermine Street, 

 Castleford, March 22nd, 1868 ! stream, north of Castleford, March 

 22nd, 1868 ! Fairburn, April, 1865, W.H.B. ; Ferrybridge, April 

 2nd, 1877, H.C. ! pond near Brotherton ! Newsholme ! Fryston 

 Park, July ist, 1871, G. Roberts ; ditch near the railway, Milford! 



5. Hatfield and Thorne — Ditch alongside Black Bank Drain, plentiful, 



April 14th, 1883, W.D.R. ! Ackholme, plentiful. May 14th, 1883, 

 W.D.R. ! Gravel Drain near Auckley Common, plentiful, May 

 14th, 1883, W.D.R.! R. Torne, common, May 14th, 1883, 

 W.D.R. ! Ditches near Blaxton Grange, plentiful, May 14th, 1883, 

 W.D.R. ! 



7. Went Vale — Pond near Smeaton Crags ! Ackworth, common in stag- 



nant pools, C.A., 1854; Ackworth, common throughout, C. A., 

 1874 ; Ackworth, H. Richardson ! 'Recorded as being found here, 

 but it seems likely that P. spirorbis has been mistaken for it ' 

 (Report of Boys' Association, Ackworth School, 1883, p. 5) ; 

 Askern, July 21st, 1881, H.S. ! common in ditches at Cowick Park 

 near Snaith, June 17th, 1882, W.D.R. ! 



8. Dearne — Canal at Royston, March 29th, 1868 ! 



10. Colne — Huddersfield, canal and ditches, rare, G. H. Parke, in Hob- 



kirk's ' Huddersfield,' p. 224, 1868; common in Huddersfield 

 canal, J.Wh. 



11. Upper Calder — Luddenden Valley, J.C., in Nat., 1875, i, 15. 



12. Lower Calder — Wakefield, very common throughout the district, with 



P. spirorbis, J.H., 1874 ; abundant on dead 'flags ' in canal near 

 Carlton, March 20th, 1864 ! canal at Stanley ! and at Notton ! 

 Walton, J.W. 



13. Airedale — Leeds and Liverpool canal at New Wortley, 1871, H.S. ; 



near Armley ! and at Calverley, H.S. ; plentiful in pond at Black 

 Hills, Leeds, April, and June 28th, 1883 ! stream, Allerton By- 

 water, March, 1881 ! Leventhorpe pastures. May 16th, 1864, J.B. ; 

 canal. Fleet Mills near Swillington 1 Lofthouse district, common, 

 G. Roberts, 1882. 

 15. W harfedale— Ditch between Weeton and Otley ! 



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

 several waters near Roseberry in Cleveland, 1879, CA. ; pond near 

 Stainton in Cleveland, Baker Hudson, 1885 ; Middlesbrough 

 district. Baker Hudson, 1883 ; Southbank near Middlesbrough, 

 H. Pollard. 



22. Upper Derwent — Scarborough, W.B. ; Scalby Bridge, W.D.R. ! 



23, Chalk lVo/(/s— Brantingham, J.D.B. 



C4 



