50 NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 



24. Holderness —Hull district, not so common as P. spirorbis, J.D.B. ; 

 Spring Dyke, Hull, J.D.B. ; ditch, strongly impregnated with iron, 

 at Figham, Beverley, not common, J.D.B.; Figham, May 29th, 

 1882 ! rejectamenta of Beverley Beck, J.D.B. ; pond near coast, 

 Skipsea, April, 1879 I Hornsea Mere, June 6th, 1881, W.D.R. ! 

 plentiful in the river Hull at Driffield, 18S2, L. B. Ross ! 



Dr. Jeffreys says when speaking of Planorbis vortex, ' This 

 species was first described and figured by Lister.' We are 

 unable to agree with this determination, and consider Lister's 

 description — Cochlea exigua subfusca, altera parte planior, sine 

 limbo, quinq; spirarum — as more applicable to Planorbis 

 spirorbis. 



The Planorbis bavayi from Guadeloupe, described and 

 figured by M. Crosse in the ' Journal de Conchyliologie ' for 

 1875, vol. xxiii., p. 329, and vol. xxiv., p. 388, pi. xi., fig. 3, 

 seems to be very closely allied to, if not absolutely identical 

 with our Planorbis vortex. 



Var. compressa Mich. 



This form was originally indicated by Draparnaud as 

 var. a of Planorbis vortex ; subsequently M. Michaud bestowed 

 upon it the name of Planorbis compressus and elevated it to 

 specific rank. There can be no doubt that it is merely a variety 

 of Planorbis vortex. 



12. Lower Calder — Dirtcar, J. Hebden. 



♦'•'♦ 



Planorbis carinatus Miill. 



Locally common in the lowlands. 



Dr. Jeffreys credits this species with only a very partial 

 distribution in this country, but our investigations on this subject 

 show that it ranges over nearly the whole of England, south of 

 Northumberland. 



Trans. Y.N. U., 18S4 (pub. 1S86). Series C 



