Illustrations of the recent conchology of Great Britain and Ireland, with the description and localities of all the species, marine, land and fresh water

IN\'OLU'l'E.] MOLLUSCA. 33 hefore and flallened behind, and furnished with a sharp carina; aperlnre sublriangular, rhomboidal, while and thickened int.er - nally, a1Hl slightly compresscd. Diametcr about thrce-cirrhlhs of an inch. 0 Found in ditches ami other slarrnant watl!rs in Great Britain ami Ireland. 0 8. PLANonms Sl'Inonms, pi. XIV, f. 42, 43.-First Ed., pi. 4 l, f. ,1,1, 45. Plano1·bis spiro1•bis, l\füller, Verm., II, P· 161; Brard, p. l ;-,6; Stunn, Fauna, pi. 45; Turton, Man., p. 115, f . 98; Alder, Mag. Zoo!. a1HI Bot., II, p. 113; Forbcs, Mal. Mon., p. 13; Thompson, Ann. ami Mag. Nut Hist., VI, p. 50; Plano1·bis vorte.i·, Drapernaud, Moll., p. 45, pi. 2, f. 6, 7 ; J effreys, Linn. Tr., XVI, p. 382; Pfeiffcr, p. 79, pi. 4, f. 8; Heli.r: spiroi·bis, Montagu, Test . Brit., Sup., p, 455, pi. 25, f. 2; Maton and Rackett, Linn. Tr., VIII, p. 191; Brown, Wernerian Mem., II, p. 524; lb., Ency. Brit., 6th Ed., VI, p. 458; Turton, Brit. Fauna, p. 187. Shell thin, semitransparent, brownish horn-colour, slightly and equally concavc both above and below; with six gradually increasing, rounded, nearly equal volutions, placed quite lateral upon each other, the exterior one nearly round, provided with a flattened carina; the whole shell co,·ered with very fine trans- versely oblique striro; aperture subrotund, and rounded below. Diameler about a quarter of an inch. Found in ditches and stagnant waters. This species seldom exceeds a quarter of an inch in diame- ter, ami may be distinguishe<l from the P. voi·tc:i; by its being equally concave abo,·e and below, and in the keel 011 the mar- gin of the outer volution being much less promincnt, and, indeed, in some $pecimcns it is nearly obsolete; when it is so, the apcrture is not at ali angulatecl. It is, besi<lcs, not so thin ancl depressed as the voi·tc,'I:, in proportion to its size. Section I I I.-Shelt sliini11g, tmnslucent; spii-e deeply um- bilicate; vol1ttio11s providecl with a slight cetrina. 9. PLAN0RBIS NITIDUS, pi. XIV, f. 48, 49-First Ed., pi. 41, f. 48, 49, Plcmoi·úis nit·idus, i\follcr, Vcrm., II, p. 263; Pfeiffer, p. 82, pi, 4, f. 12, 13; Fleming, Brit. An., P· 278; J clfrcys, Linn. Tr., XVI, p. 389; Alder, Mag. Zool. ami 13ot., II, p. 114; Thomp- son, Ann, ancl Mag. Nat. Hist., VI, p. 51; Pla.norbis lenticula- ris, Sturm, Fauna, VI, pi. 8, f. J 6; Planoi·bisfontanus, Turton, Man., p. 11O, f. 93; Plmwrbis compla11at11s, Drapernaucl, Moll., p. 47, pi. 2, f. 20, 21, 22; Rossmasslcr, Icon., II, p. 16, pi. 7, f. 116; Brard, p. 161, pi. 6, f. 4; Heli.'I:fontana, Lightfoot, Phil. Trans., LXXVI, pi. 2, f. 1; l\1ontagu, Test. Brit., p. 462, pi. 6, f. 6; Matan and Rackctt, Linn. Tr., VIII, P· 192; Brown, \Vernerian Mem., II, p. 524; Heli,i; lenticulcwis, V. Alten., p. :35, pi. 2, f. 4. Shell pellurid, glossy, ncarly clestitute of wrinkles, red<lish or greyish horn-colourcd ; lenticular, greatly flattenecl, almost cqually convcx 011 both sicles, ami a litlle <lc~ressed in the centre; with four volutions, the outer onc subcarinate ncar the middle, produced by tho gradual outwa1·<l slope of the shell, both aboi·e and bclow; a small central umbilicus on the undcr sidc; thc interna! augles of the ribs clasp the body nearly equally on both sidcs, embracing ncarly half the diametcr of tho first volution; margin vcry thin, and considcrably obliquc; aperturc contracted, and almost brought toan angle externally. Diameter not a quartcr of an inch. Inhabits stagnant watcrs, usually adhcring to aquatic plants. This shcll may be easily confoundecl with thc Segmenti11li liiieata, but is more comprcssed, and not so convcx abare, and is clestitute of thc lines which mark the scgmcnts of that shell. Scction IV.-Destitute of a cm·ina; volutio11s i·oull({ed both befare aml behincl, and deeply umbilicatcd. 10. PLANORBIS C0NTR0RTus, pi. XIV, f. 33, 34.-First Ed., pi. 41, f. 33, 34. . Plano,·bis controi·tus, Müller, Vcrm., II, p. 162; Draper- naud, Moll., P· 42, pi, 1, f. 39, 40, ,11; Sturm, Fauna, pi. 3, f. 4; Pfeiffer, p. 81, pi. 4, f. 11; Lamarck, An. San. Vcrt., VI, pt. 2nd, p. 154; Jeffrcys, Linn. Tr., XVI, p. 383; Fleming, Brit. An., p. 277; Forbes, Mal. l\Ion., p. 13; Rossmassler, !con., II, p. 16, pi. 7, f. 117 ; Turton, Man., p. 113, f. 96 ; Brard, P· 157, pi. 6, f. 12, 13, 14; Al<ler, Mag. Zool. an<l Bot., II, p. 114; Thompson, Ann. and Mag. Nat. Hist., VI, P· 51; H eli.t· conto1·ta, Linnc, Syst. Nat., I, p. 12,14; l\fonlagu, Test. Erit., p. 457, pi. 25, f. 6 ; Donovan, Brit. Sh., III, pi. 99; Brown, Ency. Brit., 6th Ed., VI, p. 458; lb., \ ;Vernerian l\fom., II, P· 524; Hcli:t· umbilicata, Pulteney, Cat. Dorset, Jl· 47, pi. 20, f. 11 ; Helix crasius, Da Costa, Brit. Sh., p. 66, pi. 4, f. 11. Shell thick, <lopressed, of a brown horn-colour, sometimcs rufous or chestnut; with fivc or six grcatly compresscd, cqual sized, compact, close-set volutions, the 011ter 0110 roundecl, the othcrs on the wider si<le rise 1warly to an eclge, an<l :1re dividecl by a decp suture, having a subumbilicus in the centre; uppcr si<le largely ancl decply umbilicatcd, exhibiting C\'cry rnlution, spirally descen<ling to the bottom; aperture crcscent-shnped, compressed, ancl clasping the body volution. Diameter a quar- ter of an inch; an<l somewhat more than a tenth of an inch in thickncss. Commo11 in <litches án<l stagnant pools. ÜENUS 41-SEGMENTINA,-Flcming. Shell divided intcrnally by trans\'crse septa into several chambers, which communicate into each other by trira<liatcd apertures. l. SEGMENTINA LINEATA, pi. XIV, f. 50, 51.-First Ed., pi. 41, f. 50, 51. Scgmcntina lincata, Flcming, Brit. A11., p. 279; lb., Ency. Brit., pi. 367, f. 8; Plano,·bis niticltts, Müllcr, II, p, 163; Dra- pcrnau<l, l\ioll., p. 46, pi. 2, f. 17, 18, 19 ; Hossmassler, !con., II, P· 15, pi. 7, f. 114, 115; Turton, Man., p. 116, f. 91; Plct- no1·bis nautileus, Fleming, Edin. Ency., VII, p. 69; Kickx, Moll. Barb., p. G6; Pla1101·Lis lineatus, Aldcr, Mag. Zool. ancl Bot., II, p. 114; Ncmtilus lacust,·is, Lightfoot, Phil. Trans., XXVI, pi. 1, figs. l to 7; Montagu, Test. Brit., p, 191, pi. 6, f. 3; Hemitltalamus lacusti·is, Lcach, l\:Ioll., p. 137; Heli:t: lineata, \Valker, Test. Min. Har., pi. 1, f. 28. Shell compresscd, subcarinate<l, exlremely pcllucicl, smooth an<l shining, horn-coloured, sometimes re<ldish-brown; upper surface convex; apcx dcprcssed, concave, an<l decply umbili- catc; with four volutions, the apical one Jost in the deprcssion, the outer onc very largc, these are bordered on their outcr edgc with a whitish spiral band, which tcrminates in thc centre