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

(MACTRACEA, 106 MOLLUSCA. 1. AMl'lllDESMA TRUNCATA, pi, XLII, f. 1. . Lígula truncata, First Ed., pl, 14, f. 1; Amplndesma t1·1m- catum, Fleming, P· 431. . with two recurvcd, promincnt tccth, which occupy the vacant space bclow the umbo in thc opposile valve; muscular impres- sions large and distinct ; pallial impression cntire. Shell subovate, rather convex, obhque; anterior side pro- d d • osterior side rather straight, and subtruncated bclow; uce , p d . . with a flexure, emanatipg from tbe umbo, an term1_natmg _on the margin; umbones small, ncarly central, and shghtly m- flectcd, bcneath tbcm a lanccolate cavity or lunulc, covcrcd with transversc, nearly obsolete striro, ami wrinkles; surfacc whitc, smooth, aud glossy; hingc with a doublc primary tooth in each valve, and a small t ooth-like knob in the left ,•alvc, locking into a cavity for its reception in the opp~site o~e; in- side smooth, glossy, and white; each valve prov1ded w1th two largc muscular imprcssions; margins rather ~hick, for thc sizc of the shell. Length threc-cighths of an mch ; breadth half an inch. Found at Greenock, by Stewart Kcr, Esq., and is in thc cabinct of Lady Jardine. GENUS 32~LIGULA,-Montagu. Shell inequivalve, inequilateral, transverscly clongated ; with a large, broacl, strong, transverse, spoon-like tooth in each valve, projecting inward~, cach íurnishcd with a pit for the inscrtion of the cartilagc; right valve furnished with a pretty large, elevatcd, ercct, compresscd tooth, situated close bclow thc bcak, fitting into a hiatus for its reception, which reaches to the beak, in the opposite vnlve; and in some species a minute tooth; exter- na) surfacc with a vcry thin, mcmbranaccous epidermis; two muscular imprcssions in cach valve, situatc vcry close to the extreme sides of the valves, the posterior ones cloublc, and ex- lending to nearly thc umbones; pallial imprcssion with a rather lnrge, transversc sinus, situated posteriorly. l. LtGULA l'R,llTENUIS, pi. XLII, f. l. Ligula p1·rotc1mis, First Ed., pi. 1'1, f. 1 ; Anatúw p1'Cetc- 111tis, Turton, Div., p, 48, pl. 4, f. 4; Amplticlcsma p1·rotenuc, Fleming, p. 432; Bontam p1·rotc1mis, Leach, l'l'!SS., p. 6; ilfya p1·cetc1mis, Montagu, p. 41, pi. 1, f. 2; Donovan, V, pi. 178. Shell oval, thin, very brittlc, compresscd, ancl semipellucid ; umbones ncnrly central, very small; beaks rathcr acule, ancl inflected; posterior side rounded; anterior side somcwhat acu- minated, ami obliquely subtruncated, at which extremity the valves are a little open; surface crcam-white, transvcrsely wrinkled, with extrcmely fine, nearly obsolete, concenlric stri:-c, covercd with an cxlremely thin, cream-colourcd, somewhat pilous epidermis ; hinge with a broad, horizontal, intcrnally projccting, ho\low tooth in each \'alve; inside white. Length abont half an inch; breadth somewhat more than an inch. This rarc llritish shell has been found at Poolc, and other places on the Dorsetshire coast ; thc south coast of D e,·on ; Frith of Forth; ami Portmarnock, lreland . GENUS 33,-TELLDIYA,-Ilrown. Scctio,~ I.-Sliclls orbicula1·. 1. TELLIMYA SUD0RDlCULARIS, pi. XLII, f. 14, 15, Tellimya subo,·bicula,·is, First Ed., pi. 14, f. 14, 15; Mya subo,-bicula,·is, Montagu, p. 39, pi. 26, f. 6; Maton and Rackctt, VIII, p. 41; I(ellia suborbicula,·is, Turton, Biv., !>· ~7, pi. 11, f. 5, 6; Flcming, p. 430; Forbcs, p. 49; Bomia injlata, Phillipi. . Shell suborbicular, vcry convcx, thin, subpclluc1d; umbones obtuse, ucarly central, slightly inílected; sidcs almost cq~al, rounclecl ; basal margin nearly parallel; surface of a yellow1sh- white colour; somewhat glossy, with faint conccntric striro; hinge with a single tooth in one valve, immcdiatcly under the beak, Jocking iuto a double incurvcd one in thc opposite valve, with a somewhat laminated tooth behind the umbo in each valve; inside glossy, white. Length three-eighths of an inch; breadth half an inch. Sorne spccimens exhibit a fine pcarlaceous lustre, when dc- privcd of the epidermis. Inhabits the Frith of Forth, Plymouth, Salcomb Bay, and coasts of t.hc ! sic of Man. It is a borcr, and pcnelratcs the hardest limestonc; Forbcs founcl it in the cavities of clcad bivalves. 2. TELLIMYA LACTEA, pl. XLII, f. 10, 11. Tcllimya lactca, First Ed., pi. l.J, f. 10, 11; 13rown, Conch. Text Ilook, p. 138, pi. 17, f. 14. Shell ncarly orbicular, inílated, thin, pellucicl, and glossy while ; onc valve with two teeth, locking inlo a triangular void in the opposite valvé, with transverse laminro on each side ; left valve with a single, recurvcd, cardinal tooth, and a central, tri- angular, lamellatcd toolh; aml one remole, lateral tooth only. About. a qunrter of an inch in cliameter. Found on thc Devonshire const, by Dr. Leach. 3. TELLIMYA TENUIS, pi. XLII, f. 12, 13. Tellimyc, ten u is, First fül., p\. 14, f. 12, 13. Shell orbicular, smooth, glossy, snow-white, with fine, irregu- lar, concentric striro, much inflated; umbones rather procluced, ancl much turned to one side; lcft valve clestitute of cardinal tccth, but providecl with two largc lateral teeth; right va\ve with two incurved, cardinal tccth, ancl a lateral onc; insicle white, and when vicwed through a strong lcns, has a shagreen- like appearance. Diamctcr three-eighths of an inch. Found at Newbigging, Northumbcrland, by W. C. Tre\'elyan, Esq., ancl is in the cabinct at \\'allington. Section 11.-Shclls trn11svc1'scly ovale. 4. TELLIMYA ELLil'TICA, pi. XLII, f. lG, li. Tcllimy<t clliptica, First Ed., pl. 1'1, f. lG, li; My<tjim·ugi- nosa, Monlagu, Sup., p. 22 ancl 16G, p\. 2G, f. 2; 1l[o11/<1c1da. fcrr11gi11osa, Turton, lliv., p. G0. Shell equivalvc, incquilatcral, suborbicular, or trans\'erscly clongatcd, elose nll ronnd; lcft \'ah-e dcstitute of cardinal tceth, but providcd with a pretly largc hialus, and two projccling lateral tccth, cach having a groo,·c in its centre; somctimes with one or two rather long teeth on thc right sicle; right \'alve Shell trans\'crsely suborntc, modcralely co1wcx, whitc, with obsolete, concenlric wrinklcs, alHI somctimcs blotchcd with rust - colourcd spots ; mnbones obtuse, situale ncarest one siele; basal margin nearly parallcl; hingc with two projccting tccth, one of which is crcct, the other slopcs inwards ancl clownwanls, thesr.