22 LYMNiECEA. 



" Shell of a dark horn-colour, with seven tapering, rounded 

 volutions ; the three next the apex are twisted like a cork- 

 screw, and terminate in a sharp point ; the five lower volutions 

 slope gradually to a carinated ridge, which commences in the 

 centre of the outer margin of the lip, and loses itself in the fifth 

 volution, giving the volutions the appearance of being flat at 

 bottom ; volutions slightly wrinkled obhquely across ; aperture 

 somewhat angulated, oval, and a little compressed; lip very thin, 

 and reflected on the columella at the base, where it is provided 

 with a deep and wide umbilicus." 



Turton described and copied my shell, in his Conch. Diet., 

 under the name of Helix te7'ebra; and in his Manuel, published 

 in 1831, followed me, in the first edition of Illustrations of the 

 Conchology of Great Britain and Ireland, pi. 41, f. 38, in con- 

 necting it with Planorhis marginatus. See second edition, p. 

 32, pi. 14, f. 38. 



7. Planorbis vortex, pi. Ill, f. 32, 33. 



Planorhis vortex, Miiller, Verm., II, p. 158, var. a; Draper- 

 naud, p. 44, pi. 2, f. 4, 5 ; Brard, p. 154, pi. 6, f. 9 ; Lamarck, 

 An. San. Vert., VI, p. 154; Pfeiffer, p. 79, pi. 4, f. 7 ; Ross- 

 massler, p. 104, pi. 2, f. 61 ; Brown, lUust. Conch, p. 32, pi. 14, 

 f. 44, 45 ; lb., First Ed., pk 41, f. 42, 43 ; Jeffreys, Linn. Tr., 

 XVI, p. 382; Turton, Man., p. 109, f- 91 ; Alder, Mag. Zool. 

 and Bot., II, p. 113; Forbes, Mai. Mon., p. 13; Thompson, 

 Ann. and Mag. Nat. Hist., VI, p. 50 ; Planorbis compressiis, 

 Michaud, Compk, p. 81, pi. 16, f . 6 and 8; Helix vortex, Linne, 

 Syst. Nat., I, p. 1242; Montagu, Test. Brit., p. 454, pi. 25, f. 

 3 ; Brown, Wernerian Mem., II, p. 524 ; lb., Ency. Brit., 6th 

 Ed., VI, p. 458; Donovan, Brit. Sh., pi. 39, f. 1 ; Fleming, Brit. 

 An., p. 278. 



Monstrosity. . The aperture provided tvith a thicJcened inter- 

 nal rib, Michaud, Compl., p. 80, pi. 16, f. 3, 4, 5; Rossmassler, 

 Icon., I, p. 105, f. 62. 



Shell brownish horn-colour, transparent, very thin, flattened 

 above, and a little concave below ; with six or seven gradually 

 increasing, obliquely and transversely striated volutions, convex 

 before and flattened behind, and furnished with a sharp carina ; 

 aperture subtriangular, rhomboidal, white and thickened inter- 

 nally, and slightly compressed. Diameter about three-eighths 

 of an inch. 



