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

CoNcHACEA.] MOLLUSCA. I fo11ml this new British specics immediately under the colnmnar greenstone rocks, ll'est eucl of Arthur's Seat, near ~dinhurgh, plentiful in a <litch al the \Vells of \Veary, which 1s now co,·crcd up by thc raihrny. '1. PISll)IUM Al'l'ENDICU!.A'~A, pi. XXXIX, f. 25. Cgclas appc11rliculata, Leach, i\ISS.; Turton, Man., p. 15, f. G; Pisirliwn lfc11slou:im111111, Thompson, Ann. aud l\fa<r, Nat. Hist., VI, p. 5-1; Tellina Ifc11slo1ci11111w, Sheppard, Linn. 1.'rans., XIV, p. 150. Shell obliqnely Ol'al, mnch inílatcd; with regular, wcll defined, concentric grooYes; beaks vcry tumid, considerably produced, ami somcwhat tubercled. Length an eighth and a half of an inch; breadth not quite a quarler. Fonml in slow running streams, but is very rare. This shell seems nearly allicd l o P. obliquum, from which, howe,·cr, it diffcrs, in its grealer convexity, and the protrusion of the beaks, at the base of which is a grooye, or dark zonc, giring thcm the appcarance of tubcrcular appcndages. 5. PISIDIUM NlTIDUM, pi. XXXIX, f. 26. Pisiclimn nit-i<lum, Jenyns, Monog., p. 16, pi. 20, f. 7, S; Thompson, Ann. ami Mag. Nat. Hist., VI, p, 53. Shell suborbicular, or.slightly oval; umbones largc, and blunt; externa! surfacc very glossy, of a pale horn-colour, and coverecl with fine, concentric strire, which are wicler-set and cleeper on the umbones. Inhabits J3atlersea Fields, some ditches in Cambridgeshire, ami ditches near \Vorcester; in a pond al \Volfhill, near l3elfast, and other places in that neighbourhood; Lough Gill, County Sligo, Portarlinglon, and Finnoe, Ireland. 6. PISIDIUM PUSII.I.UM , pi. XXXIX, f. 27. Pisidimn pusillu-m, Jenyns, Monag., p. 14, pi. 20, f. 4 ancl 6; Thompson, Ann. ancl Mag. Nat. Hist., VI, p. 53; Cgclas pu- silla, Turton, J3rit. J3iv., p. 251, pl. 11, f. 16, 17; lb., Man., p. 16, pi. l, f. 7; Alder, Mag. Zoo!. ami Bot., II, p. 119. Shell ncarly orbicular, slightly ovatc, subcompresscd; um- bones prominent, alHI very obl use at t.he points; sides somc- what llaltened, ancl very slightly incquilateral; surfacc of an olivaccous-brown, wilh vcry fine, conccntric strire. Inhabits ponds near London, ami many othcr localities. In Trcland, according to Thompson, it is the most common of the genus, frequenting ponds ancl clrains. 7, PISIDIUM CINEIIEUM, pi. XXXIX, f. 28. Pisiclium cincl'cum, Alcler, Cat. Sup., p. 4; lb., l\fag. Zoo!. and J3ot., II, p. 119; Thompson, Ann. and l\fag. Nat. Hist., VI, p. 5,1. Shell compressed, suborntc; umbones but slightly prodnced, obtuse at the points, is sometimes capped; lower margins of the mires meeting al an acute angle; surface of a grayish ash- colour, ancl finely slriated concentrically; with a fcw super sulci, which fonn dcepcr lrm1s\·crse zones. This shell is more orntc in its form than any of its conge- ners, excepting thc P. obliquum, ancl will be at once rccognize<l by being more comprcssecl than thcm, a11CI by its ashy hue. Vm·ictg J. Somewhat more ventricose, with the umbones a little more produccd. Inhabits ponds near Ncweastlc, ami other localitics in the Norlh of Englancl. Mr. Thompson says it is witlcly spread throughout Ireland, although no where common. He par- ticularizes Holywoocl I·Iouse, Downshire; YoungroYc, ncar l\Iiddleton, County of Cork, by Miss M. l3all; Killercrau, County of Gal'.1·ay, ami Portarlington, by the Rev. B. J. Clarke ; ancl ne,ghbourhood of Dublin, by Thomas William vVarren, Esq. Sun-D1v1s10N~TENUIPEDEs. The mantle barcly nnitecl before; foot small, narrow, ancl comprcssed ; shell hal'ing but a moclcrate gape. FAMILY I~NYMl'IIACEA. 1-Iaving ne\·cr more than two primary teeth in the same valvc; shcll often gaping slightly at the lateral extrcmitics; ligamcnt externa!; umboncs generally projecting outwarcls. Section I .-Destitute of lateml lccth. GENUS 17.-CnASSINA,-Lench. Shcll suborbicular, lrans1•crse, equil·al\'e, incquilatcrnl; hingc with two strong, divergent, primary, large, central teeth in the right valve, ami one small, ncarly obsolcte tooth, together with an inclistinct, lateral one in the lcft valve; two ovate or oblong, remate, lateral, simple, muscular imprcssions in each valve, with a third vcry small one, situate immecliately below thc indistinct lateral tooth, or at thc end of the posterior externa( depres5ion, and in some inslances mingling with the lower terminatiou of the posterior muscular impression, ,rhich is always simple, ami not sinuated. 1. CnASSINA DANMONIENSis, pi. XXXVIII, f. 1. Crassina Danmonfonsis, Firsl Ed., pi. 18, f. 1 ; Lamnrck, V, p. 55,1 ; Venus Damno11ia, Monlagu, Sup., p, 45, pi. 29, f. ,J ; Crnssina su/cata, Turlon, Bil'., p. 131, pi, l 1, f. !, 2; Astm·tc Danmonia:, Fleming, p. 440; Asta,·te Dm1monic11sis, Forbes, p. 50. Shell slrong, thick, subcordiform, subcomprcssed; with many regular, obsolctcly striatecl, strong, equidistant, transverse ribs; intcrl'cning furrows rather decp, quite smooth; umbones nearly central, anteriorly reclined, ami rather acule, with a dccp, lanceolate lunulc uncler them ; surfacc covered with a dark redclish-brown, strong epidermis; insi<le white, but not glossy, except rouncl the margin, which is finely crcnatcd, ancl vcry blunt at the edge. Found on thc Devonghirc, vVelsh, and Northumberland coasts; also the Friths of Forth and Clyde; Lough Strangford ancl Portmarnock, Irclancl. 2. CnASSINA ScoT1cA, pi. XXXVIII, f. 9. Crassina Scotica, first Ed., pi. 18, f. 9; Turton, J3iv., p. 130, pi. 11, f. 3, 4 ; Venus Scotica, Montagu, Sup., p. 44; Maton and Rackelt, p. SI, pl. 2, f. 3; Lamarck, V, p. 600; Aal<wtc Scotica, Fleming, p. 440; Forbes, p. 51. Shell thick, subcordiform, subcompresscd; umbones nearly central, considerably reclined anteriorly; bcneath them a lance- olate, subcordiform lunulc; surfacc with many regular, rathcr. elevatccl, somewhat parallel, transversc ribs, which are narrowed townrds thc posterior sicle; whole surface covered ,~ith a thick, vellowish-brown epidermis, but recldish-brown in others; insidc: ;mooth, while; with the margin plain.