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

80 MOLLUSCA. [NAYADES. Shell very thin, with the hinge line almost straight, and, ascending, forming an angle, from whence it descends in nearly a parallcl dircction, assuming an obtuse point; anterior si<lc slightly angulated; the basal line arcuated, and <lescen<ling con- si<lerably, in consequence oí which the posterior si<le is Yery <leep, bcing a thir<l more than the anterior one; surface covere<l with a vcry bright yellowish-green epidermis, frequently wilh divergent rays of a deeper bue; ligament not protruding beyond the margin of the hinge line. Found in the canal, near Keighley. Variety 6. CoMPLANATA, pi. XXVIII,• f. 6, 7. Anodonta complanata, Ziegler Museum; Rossma.ssler, I, p. 112, pl. 3, f. 68, a; .rlnodonta compnssa, Menke, Syn., p.106; a va1'icty, Rossmasslcr, IV, p. 24, pi. 20, f. 283; Ziegler Mus.; Anodonta 1·homboiclea, Schlüt. Shell vcry thin, comprcsscd, ellipticálly-ovate; the superior, or hingc margin asccnding, in a somewhat curved line, to the tcrmination of thc ligament, from whcncc it <lcscencls and ter- minales in a proclucc<l beak, quite at thc lower angle of thc posterior sido; basal lino vcry straight, with a slight curvalure ; anterior margin rounclcd, and narrow, ncar to which thc slightly dcvt'iopcd uinbo is situatc; wholc surface with concentric wrin- klcs, ami covcrcd with a rc<ldish-brown epidermis. This variely is found in thc rivcr Caldcr, ncar Wakclield; and i l has bccn forwardccl to me from thc Tren!, at Rcpton, ncar Burton, by thc kinclncss of Sir Oswalcl Moslcy, Dar!.., a gentleman clistinguishcd for the clcep intcrést which he takes in thc admnccmcnt of Natural Scicncc. Váriety 7. AvoNENs1s, pi. XXIX, f. 2. il'l!]tilus Avone11sis, Montagu, Test. Drit., p. 172; Turton, llrit. Fau., p. l Gti; l,fytilus Cygneus, va,·. /3, Maton ancl Rack- ctt, Linn. Tr., VIII, p. 110, pi. 3 A, f. 3; Flcming, Edin. Ency., VI r, p. 99, pi. 20G, f. 5; A11oclonta Anatina, va,·., Rossmasslcr, vr, P· 5i, pi. 30, r. ,lis. Shcll o\·oicl, or subrhomboidal, vcntricosc, rathcr t.hick, in ,omc spccimcns \·cry thick ; anterior margin rounded, short; posterior margin long, ancl pointccl; hingc line subarcuatccl; basal line slightly cun•ccl; externa! surfacc gcncrally rough, with sharp conccntric wrinkles, covcrcd with a vcry thick, variously colourccl, rather dull epidermis; somctimes olivaccous, and at othcrs rcclclish-brown. This rnricty is subject to considerable variation of form ancl si1.c, ancl is in general wcll markcd. It is usually of a dull whitc internally, with but littlc of thc pcarly lustre so prcvalent in its congeucrs. Founcl in thc AYOn ancl New Rivcr; also near Tisbury, Wilt- shirc; thc Trcut, near Durton; ncar Stceton; the canal, ncar Halifax, ancl of a largo sizc in thc canal, ncar Sowerby Bridge, Yorkshire. Val'id!J 8. PONDEROSA, pi. XXX, f. l, 2, ami pi. XXIX, f. 3• . A11odonpo11dc1·osa, Pfciffer, II, p. 31, pi. 4, f. l to 6; Ross- masslcr, IV, p. 24, pi. 20, f. 282; 11/!Jlilus C!]g11cus, i·ar. {3, l\faton ancl Hackctt, Linn. 'l'r., VIII, p. 109, pi. 3 A, f. 3. Shell large, thick, ponclcrons, rhombic-oval, \'ery \'Cntricose; Clltcmally wrinklecl; with thc epidermis rough, librons, ami scmiYillous at thc rouncled anterior cxtremity, ancl al the base; posterior sido long, subrostrated, ami subtruncatecl al its cxtre- mity; base but slightly bent, or nearly parallel; hingc lino considerably arcuated, with a long ligamcnt, from whcncc it somewhat abruptly descends; beneath the ligament a sinuatecl groove, rising abruptly, and forming a ventricose disk; umboncs rather tumid, and <lccorticated ; the ligamentary sinus small, subcorclate; insicle bluish-white. Length two inchcs ancl three- eighths; breaclth four inches ancl five-eighths; thickncss two inches and a half. I was favoured with this interesting 1•ariety by my friend Mr. Henry Johnson, Curator of the Museum, Royal Institution, Liverpool, who founcl it at Otterspool, Aigburth, on thc pro- perty of John Moss, Esq., who has since most kindly suppliccl me with a complete series for investigation. It also occurs in Loch End, near Edinburgh. Another hanclsome variety of this shell inhabits the lake at Rolleston, thc scat of Sir Oswald Mosley, Dart., near Durton-upon-Trent, to whom I am in<lcbted for a fine series. The latter varicty is somewhat more acuminatcd in the beak- ecl siclo, ancl <levoid of thc villosity of thc Ottcrspool varicty, in which respcct it agrees with that found at Loch End. This she!l has been mistakcn for thc A. Avone11sis, by somo Dritish Naturalists. It is, howcver, considerably more inflatccl, in proportion to its size, ancl a third larger. Vai·iety 9. SunnnoMDEA, pi. XXX, f. 3, 4. Anodon subi·hombea, Drown, MSS.; Anoclont<, pisci11alis, va1·.? Rossmasslcr, VI, pi. 30, f. 416. Shell thick, subrhomboidal, rathcr inflatccl; anterior sicle slightly procluccd; hinge line ncarly parallcl, ancl asccucling towards the posterior sicle; ligamen! long, subarcuated, from whcnce it sucl<lenly clcclincs towards thc somewhat truncatecl cxtremity; basal lino considerably arcuatccl; exterior surfacc but slightly wrinkled transverscly; umboncs small, and acule ; insidc bluish-white, with faint pcarlaccous rcflections. This variety differs from the A. piscinalis, in bcing more ponclerous, ancl more inflatcd, in the hinge line being more arcuatcd, ami in bcing less rostrated. Founcl in the Irwcll, ncar Manchestcr, by my estecmccl friend Mr. Samucl Gibson, of I·Icbden Driclgc, Yorkshirc ; to whom I am indebtcd for spccimcns. Varict!} 10. P1sc1NA1..1s, pi. XXVIII,* f. 3, 4, 5, Anoclontc, piscinalis, N ilsson, p. 116, No. 3; Drapcrnaucl, I-Iist. eles i\foll., pi. 12, f. 2; Rossmassler, IV, p. 23, pi. l!), f. 281; Anodo11ta vent?-icosa, Pfciffer, II, p. 30, pi. 3, f. 6; Alcler, lVfog. Zoo). ancl Dot., II, p. 118; woocl cut, Kcnyon, Mag. Nat. I-Iist., I, f. 188; 11/ytifos maculatus, Shepparcl, Linn. Trans., XIII, pi. 5, f. G, young shell. Shell subovate, vcntricosc, thick; hingc linc ascencling in a wavcd, subarcuatccl swccp towards thc po~tcrior sido, and eles• ccnding i11 a hollow bent linc, cnding in a proclucccl, turnecl upwarcls beak; basal margin consiclcrably arcuatcd, ancl ascend- ing rathcr abruptly towards the posterior sicle; outer surfocc coYerccl with a thick, shining, olivaccous epidermis, with many obscure, racliating linos of a darkcr huc. Found in thc canal, ncar 13irminoham; all(I in Combermcrc, Chcshirc, whcrc I procurccl an cxl;1si\·c series, whilc on a Yisit at the Abbey, through thc politc aftention of Yiscount and Lady Combcrmere. Vio·icl!J 11. HosrnATA, pi. XXVIII,'-' f. 8, !). A11odo11ta rostrata, Kokcil i\Iuseum; Hossmasslcr, IV, p. 25, pi. 20, r. 28,1.