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

86 MOLLUSCA. [CARDIACEA. l. AncA NoJE, pi, XXXIII, f. 1, 2, 3. .A.1·ca Noa:, First E<l., pi, 25, f. 1, 2, 3; Linné, Syst. Nat., p. 1140, No. 169; Lamarck, VI, pt. 1st, p. 37; Montagu, p. 139, pi. 4, f. 3, 3; Donovan, V, pi. 158, f. 1, 2; Turton, Iliv., p, l 66; Flcming, p, 397. Shcll rhomboidal, cymbiform ; thc smaller cncl of each valvc turning inwards to mcct cach othcr ; umboncs situate nearest to onc sidc, separatcd by a pretly widc cardinal arca, which is smooth and glossy; apcx promincnt, slightly inflcctcd ; bingc parallcl, with numcrous tccth, thosc in thc centre perpendicular, an<l obliquc towards thc sides; externa! surface with numerous, longitudinal, divcrgent striro, which cmanatc at thc apcx, ancl tcrminatc on thc margins, thosc on thc narrowcr sidc wider ami strongcr, assuming nearly thc aspecl of ribs, thc wholc crossed by fine, trarisverse striro, pro<lucing an clegant rcti- culated appcarance ; colour rufous-brown ; insidc white, or slightly tinged with purplish-brown, witb thc margins slightly crenatcd. Found on Milton Sands, south coast of Devon ; at Land's End, Cornwall; and also al Guernsey. 2. AncA FUSCA, pi. XXXIII, f. 4, 5. Arcafusca, First Ed., pi. 25, f. 4, 5; Lamarck, VI, pt. 1st, p. 39; Donovan, V, pi. 158, f. 3, 4; Montagu, Sup., p. 51; Turton, Biv., p. 167; Flcming, p. 397. Shell cymbiform, trans1•crsely clongated; umbones prominent, rounclcd, obtusc, ancl somewbat remole, being scparatcd by a prctty broad, ílat, cardinal arca, and situatcd nearer one end; whole outer surface fuscous-brown, co1·ered with fine, divergcnt, longitudinal striro, which are dccussntcd by transvcrsc, sharp striro; posterior sidc somewlmt lruncntcd; insidc glossy, ancl white; mnrgin with vcry fine crcnulations. Found at Cornwall ancl south coast of Dcvon. Lady Jardinc posscsscs n spccimcn which was founcl ncar \:Vcymouth. This shell diffcrs from .11. Note in being longcr in propo rtion lo its brcndth, in thc striro being finer, ancl the colour more of a ycllowish-brown. 3. AncA LACTEA, pi. XXXIII, f. 6. Arca lctctca, First Ed., pi. 25, f. 6; Lamarck, VI, pt. 1s t, p. ·10; Montngu, p. 138; Dono,·an, IV, pi. 135; Flcming, p. 398; Arca pc1fon111s, Tmton, Div., p. 169, pi. 13, f. 23. Shcll subrhomboidal, roundcd at both cxtrcmitics; umboncs not quite central, blunt, ancl placed somcwhat remole; cardinal arca smooth; hingc parallcl, with numcrous tcelh; outcr surfacc co1·crncl with a· pilous, palc ycllowish-brown epidermis, bcncath which thc shell is milk-whitc, with numerous, closc-scl, regular, longitudinal slriru, thc intcrstices bctwcen the striro fincly punc- lurcd, producing thc appcarancc of bcing rcticulatccl, whcn vicwcd through a lcns, rrossccl by a fcw concentric wrinklcs, or lincs of growth; insiclc white, with a plain mnrgin. Length half an inch; brcadth thrcc-quarlcrs. Thc sidcs in thc young shells are for thc most parl oblique, ami subtruncatccl, ancl assume a more roundcd form as thc shcll adranccs in growlh; somc specimcus h:we also transvcrsc s triru, which, howcvcr, is but of rarc occurrcncc. Found plcntifully 011 the Dcrnnshirc all() Cornwall coasls. ·l. AncA BARUATA, pi. XXXIII, f. 7. Arca barbata, First Ecl., pi. 25, f. 7; 13rown, Wcrncrian l\fo1n., II, p. 512, pi. 2'1, f. 3; Lamarck, VI, pi. 1st, p. 5!); Fleming, p. 398; A1·c11. 1·eticulata, Turlon, Ilh·., p. 168. Shell transvcrscly elongatcd, strong, white, very finely rcti- culated ; covered with a rcddish-brown epidermis; from thc umboncs to the margin diverge a numbcr of nearly equidistant, llat ridgcs, covered with vcry fine, short, and thick-sel brown hairs; ali round the margin it is besct with a byssus of rathcr long, stiff bristlc-likc hairs; in thc hollows at thc anterior and posterior sidcs, it is thickly covercd with bristlcs of a very clark umbcr-brown, rathcr small at the umbo, and increasc in size as they diverge from it on both sidcs, and obliquc in oppositc dircctions; inside modcratcly glossy, growing dimmcr as it approacltcs tite umboncs of tite sltcll, wltitc, with palc glossy rays, ami clouded witlt pale chestuul; margin finely crcnulated. Breadth ncarly double its length. Discovercd in Louglt Strangford, County of Down, Ireland, by Dr. Macgec, of Belfast. 5. AncA TETRAG0NA, pi. XXXIII, f. 20, 21. Ai·ca tctragona, Forbes, Mal. llfon., p. 41; Poli, p. XXV, pi. 25, f. 13? Shcll transvcrscly oblong, obliquely quadrangular, vcry tu- mid; an oblique rib lakcs it rise al thc umbo, and terminales 011 tite anterior sidc; umboncs but sliglttly produccd, ancl vcry remole, separatcd by a very large, ílat, ncarly lozcngc, cardinal arca, from lhc siuistr,al sidc of which it sucldcnly sinks, forming an acule anglc, by thc meeting of the arcuated basal linc; car- dinal arca with a largc lozcngc imprcssion, subquadrangularly striatc, tite lines of the onc valvc meet ing thosc of the olher; wholc surface witlt longitudinal an<l lransvcrse stri:u; colour brownish-whitc; coverccl with a tltin, pilous epidermis, a1HI fringed round thc margins of the valves, wltich are longer at the bcak ; basal margin prol'ided with a lnrge, central, oblong, lozcngc ltialus, for thc passagc of thc byssus; insi<lc white, tingccl with purplc nt onc si<lc; hinge linc slrnight, with many leeth, which are numerous posteally aiul fcw anleally, t ite mar- gin with fine crenulations. Found in tite Calves 011 thc \Vest coast of Irclnnd, wherc it burrows in hard clay ancl limcslonc rocks; ami drcdgecl by Profcssor Forbcs off tite coast of Ilallaugh, Islc of Man. I obtainccl it from !lir. Richardson, with onc of the specimens, embcdde<l in limcstonc. FA)IILY lll.-CARDIACEA, Primary lceth irregular botlt in form and situation, an<l 111 general accompanicd by onc or lwo lateral tccth. GENUS 7~IsocAm>u.-Lamarck. Shcll cquirnll'c, hearl-shapcd, rnntricosc; bcaks very dislant , divergen!, ancl involutc; hingc with two primary compressed tcclh in cach rnlvc, thc onc ncxt thc apcx inflectcd under thc umbo, ami with onc elongatcd, lateral tooth, situatc imme- diatcly beforc tite ligamcnl, wltich is cxlernal, a11Cl divided into two ligamenls at its posterior cxlremity, botlt of which are di,·crgcnt to the point of tite bcak in eaclt rnl\'C; botlt vah-cs prol'idcd witlt lwo lateral, ramotc, muscular impressions, tite linear imprcssion of thc mantle is cnlire, and cxtending from one muscular imprcssion to thc othcr. l. IsocAnDIA Con, pi. XXX, f. O, ami pi. XXX/' f. 5. lsocanlia Co1·, First Ed., pi. 23, 2·1; Lamarck, VI, pt. 1st, p. 31 ; Turton, Bi,·., p. 193, pi. 1-l; Flcming, p. '11 !J; Chama