40 NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 



or angularity and in having fewer whorls. The colour character 

 added by Dr. Jeffreys is only of subsidiary importance. 



12. Lower Calder — Dirtcar (Hebden). 



Var. albida Nelson. 



Mr. Wilcock informs us that the specimens upon which 

 the variety was founded were from St. Swithin's Wood near 

 Stanley, and not from Newton as stated by Mr. Nelson, J.C, 

 iv., p. 25. 



12. Lower Calder — Dirtcar, J.H., 1874; Newton near Wakefield, J. H. ; 

 St. Swithin's Wood near Stanley, J.W. ! 



Monst, scalariforme 



23. Chalk Wolds — Flamborough Head, W. C. Hey, 1879. 



Mr. Wilcock has found some very curiously contorted 

 specimens at Altofts near Normanton. 



Planorbis vortex (L.). 



Common and widely distributed. 



This species, though widely diffused, is not so universally 

 common as F. spirorbis, and does not range quite so far north. 



In Yorkshire it is also less common, and its known locali- 

 ties are not so numerous. 



Mr. Lionel Adams remarks that this species is less liable 

 than the preceding to disfigurement of the epidermis when 

 living under similar conditions in the same pond. 



2. Lune and Ribble — Common in a pond by the side of the Ribble at 



Gisburn, Ap. 18, 1881, W.D.R. ! 



3. Vale of York — Milford ! pond near Church Fenton Station ! pond at 



Riccall I Wetherby, 1877, E. E. Prince ! a number of dead speci- 

 mens in a ditch at Little Fenton, June 21, 1875 • Clifton Ings, 

 R.M.C. ; pond by the Foss, York, R.M.C. ; Strensall Common! 

 Bubwith, J.D.B. ; Boston Spa and neighbourhood of Tadcaster, 

 J. Emmet. 



Trans.Y.N.U., 1883 (pub. 1885). Series C 



