8 NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 



3. Vale of Ko;7/ -Tadcaster, ILC. Wetlierby, H.C 



4. /■/i/mbsr^Milford ! Knottingley, J. W. Hambleton ! Selby ! Goole, 



common, R.W-M. 



6. Trent — Conisbro', J.W. 



7. Went Vale — Ackworlh, common, CA., Norton ! Pontefract ! Bentley 



near Doncaster. 



8. Dearne — Canal, Barnsley ! 



10. Co/ne— Luddenden, J.C, Huddersfield, plentiful, J.Wh. 



12. Lower Calder — New Miller Dam, J.W. Canal at Wakefield ! Canal, 



Normanton. 



13. Airedale — Leeds and Liverpool Canal at Ringley ! Kirkstall ! Rodley ! 



Swillington ! stream, Castleford ! Rothwell, ILS. 



17. V/ensleydale — Birk Rigg, H.C. Ripon, common, J.D. River Ure at 

 Cover Bridge ! 



22. Denuent — Scarbro', W. B. 



23. Chalk lyo/c/s^Brantingliam, abundant, J.D.B. Brough ! 



24. Holderness — Barmston and Skidby Drains, J.D.B. 



Var. flavescens, Macgill. 



4. Hurr.ber— Goole, R.W.M. 

 10. Colne — Canal, Huddersfield, plentiful, J.Wh.. 



Var. Pisidioides, Gray=Sph?erium Vermontanum, Prime. 



This variety is, according to Dr. Gwyn Jeffreys, identical 

 with 6*. Vermontanutii^ Prime. An inhabitant of Lake Champlain 

 and Vermont. 

 10. Co//ie— Deighton, J.Wh. 



■ :0: 



Sph^rium rivicola, (Leach). 



Closely represented in the Western Llemisphere by the .S! 

 dentatiim of Prime, a very nearly allied species, which appears 

 to differ only in its smaller size and rather more abruptly truncate 

 posterior margin, judging from specimens received from Mr. 

 Hemphill, of California, and collected in that region. .S". rivicola is 

 interesting in having been first collected in England at Doncaster, 

 but the localities where it has been found in the county are as yet 

 but few, 



'iVaiiEiV.N.U., 1S77 Series C 



