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

114 MOLLUSCA. [PHOLADARIA. cular impressions, exlending ncarly ali along the arch_ of thc cardinal margin; pallial impression interruptcd, but dcstitutc of a sinus; Jigamcnt cxtcrnal, linear, º."pandc_d over_ the outer ~ f tlic cardinal faccls ; carllla«c s1tualc m a small, sunacc o o . short, triangular pit, immccliately undcr the umboncs, wluch are slight)y promincnt • J. GALEOMMA TURTONI, pl. XXIII, f. 15, 16. Galcomma Ttn·loni, First Ed., pi. 31, f. 15, 16 ; Turton, Zool, Journ., II, p. 361, pi. 13, f. l. Shcll tumid in thc miclclle, comprcsscd towards the extrc- mities, which are roundc<l an<l closed ; with a largo oval gap at the basal margin; hinge dcstitute of teeth; of a <lirty or crcam- whitc colour; surface covcrcd with closc-set, irregular, trans- verso, intcrrupted opaque linos ; umbones promincnt. Length two lines anda half; brcadth not quite half an inch. Dredged in thc English Channcl, by Dr. Turton. GENUS 47.-PnoLAs.-Linnrous. Shell transvcrscly oblong, equivalvc, grcatly incquilatcral; ncarly the whole spccics gaping at both cn<ls, ami most of thcm with the opening very largo at thc anterior cm!, an<l extcnding along the basal margin; in sorne species, howcver, it is nearly closc<l by a testaceous, almost smooth, somewhat tubular pro- longation of the vah•es; hinge in various spccies with an unc- qually sizecl, small, rccurvecl toolh in each valve; externa] surface gcncrally roughcncd with muricate<l striro, prcsenting a rasp or filc-likc appcarance; most of the specics providcd with a grentcr or lcsser numuer of accessory valves, ~ituate ncar thc fulcrum of thc hinge, al)(] connccted with thc shcll only by the epidermis, which passcs 01·er them; cach vall'C furnishc<l with a long, cur,·cd, llat, tooth-like, tcstaceous proccss, projecting from thc interior of the shcll, immcdiately within the umboncs; in some spccies this is cxpanded, and spoon-shaped; anterior dorsal margin near the beaks reílectecl, close, ancl llattened clown upon the umboues in some spccies, all(l in others a second margin is procluced, situatc remole from thc first, with thc intcrvening spacc di,·ide<l by a series of transversc septa; two principal imprcssions, formed by thc aclductor musclc, one of which is placed on thc rcflcctecl margin ovcr thc bcaks, ami the other intcnnediatc, bctwecn thc umbones ancl the posterior siclo; mus- cnlar imprcssion with a largo sinus in its narrowcr part, the im- prcssion bcing somcwhat cxpandcd near to thc sinus. fit'ction 1.-f?alues clividcd by a longitudinal groove. J. PnoLAs cnisrATA, pi. XLVIII, f. 1, 2, 3, 4, 5. Pholas crispata, First Ed., pi. 9, f. I, 2, 3, ,J, 5; Montagu, p. 23; Donol'an, II, pi. 62; Iu., Pliolas parvus, youn" shcll 1 G º 'l' 13· 6 I' · 0 ' p . ., ; urton,_ 11·., p. ; ·lenung, p. 456; Forbes, p. 5i. . Shell stro'.1g, mílatcd, transvcrsely subol'al, very open al both s1dcs; c>11c Sl(IC rounded; thc auterior onc acutely beaked al which si,lc thc superior margins, from the umbonal rc••io: 1 to lhc extremity, are 'thickenecl, smooth, and reflectccl, ~l'ilh a hollow bchiml; from thc interna! cnd of such rcílection cma- nates a longitudinal, rathcr deep furrow,-rnryin" in width in diffcrcnt indil'idnals,-:md tcrminating on the b~isal marnin. po~lcrior side ncarly plain, with irregular, transl'crse, slinh¡ wrmklcs; anterior siclc wi1h numcrous, thin, undulatin" c 0 011 _ . . kl º' cent ne wrm · es, ami longitudinal, dircrgent grool'cs, producing a reticulated appcarancc; insidc smooth, whitc, ancl glossy, with an clel'ated, longitudinal riclgc, corresponding to thc externa! furrow; below thc umbonal rcgion in both valves is a long, ílat, greatly curvcd, transverso tooth; Clltcrna\ surfacc of a dull, opaque ycllowish-white, somctimcs of a fcrruginous huc. Found on many of thc British and I rish coasts, burrowing in limestonc or clay, its relreat bcing marked by a circular hole 011 thc surfacc, 2. PHOLAS PAPYRACEA, pi. XLIX, f. 4, 6, 7, 9. Pholas papyracca, First Ed., pi. 8, f. 4, 6, 7, 9; Goo<lall, MSS.; Turton, Biv., p. 2, pi. 1, f. 1, 2, 3, 4; Plwlas lamellata, Flcming, p. 456; Pltolculidcc, Loscombiana, Flcming, Conch. Dict., p. 147. Shcll semiclavate; anterior siclo ventricosc, and vcry obtuso, somewhat roundcd, and closed when the valves are shut, and quite smooth for about half of its surface; open ancl truncate at the posterior ancl smallcr sido, which is providcd with a produced acccssorial ring, of a brownish papyraccous appcarancc, an<l extending about threc-cighths of an inch bcyoncl thc tnmcatcd lcrmination, its diamctcr increasing out- wardly; thc hinclcr half col'cre<l with el ose-set, slightly obliquc, crenate ribs; near the centre of each vah-e is a somcwhat oblique, longitudinal groorn, bcyon<l which thcy are coverecl wi th coarscr ancl more parallcl striro; insidc <lull whitc, with a longitudinal rib corrcsponcling with thc externa\ groovc; tecth rathcr short, and compresscd ; on thc margin ahove therc is an crcct, slightly triangular, somcwhat concavc plate, much largor in onc vahe, an<l cont.aining a portion of thc animal fold, but dcstitutc of a pcrmancnt ligamcnt. Lcngth three-quarters of an inch; brcadth eleven inchcs al)(( threc-quarters, including thc annular appendage. This ring is divisable into t11·0 cqual and similar parts, the segmcn!s bcing united by a thin clastic membranc; the back is providcd with two acccssorial appenclagcs, with the margins of thc valves rcflccted at their anterior side, so as to form a douhlc obtuso kccl, rcaching as far as the longitudinal grool'c, ncar the cnd of which is a kind of elcvatcd joint, whcrc the accessorial vahes are attachc<l. 3. PIIOLAS LAMELLATA, pi. XLIX, f. 10, 1 l. Pliolas lamcllata, Turton, Bil'., p. 4, pi. 1, f. 5, 6. Shcll very open antcriorly, whcrc thc vall'cs are dcprcsse<l, slightly re!lected, ami produced into a bcaked fcrmi nation, thc margins of uolh l'ah-cs on this siclo bcing strongly scrratccl, all(I ncarly closecl posteriorly; with an crcct, laminar proccss 011 thc superior margin, ovcr thc umbonal rcgion; \'aires with a nearly central, longitudinal grool'c, emanating from thc umboncs, ami terminating on thc base; whole surfocc col'ercd with closc-sct, somcwhat obliqucly transl'crsc, crenatc ribs, which becomc coarscr ami straightcr bcyond the longitudinal groo,·e ; insidc white, all(] smooth, ll'iLh a longitudinal rib in the llliddlc, cor- rcsponding to thc externa( groo\'c; tccth long, colllprc,scd, and slcnclcr, with a triangular proccss ahol'e thcm ; dcstitutc of acccssorial l'ahcs. This spccies is ncarly all icd to, if nol a rnricty of thc prc- ceding shc\l. It was introducccl by Dr. Turton, who remarks, "It has bccn suggestcd to us, that a bclicf is cn tcrl aincd of this bcing thc young of P. J){l]'!Jl'acert. l3ut as wc harc oppor- tunitics of cxamining cach of thcm in crcry stagc of thcir growth, uoth pcrfcct ami with thc l'ah·es scparatcd, wc c:m with