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

98 MOLLUSCA. [CoNCHACEA, GENUS 20..-MYnTEA.--Turton. Shell subtrinngular, equivalve, ncarly equilateral; umboncs almost central, with a deep, lanceolate lunule beneath them ; hingc with a single, central, primary tooth, and a lateral tooth 0 11 each sidc, in the lcít \'alvc, and two cardinal and ~wo slig~1tly defined lateral teeth in the right valve; muscular 1mp_ress1ons reniform, and shallow; pallial imprcssion entirc; hgament external. I. MvnTEA Sl'INIFERA, pi. XXXVI, f. 15, 16, and pi. XXXIX, f. 14, 15. O,·tygia spinife1·a, F irst Ed., pi. 20, f. 15, 16; Ven,us spini- Jera, Montagu, p. 577, pi. 17, f. 1; Maton and Rackett, P· 78; Fleming, p. 443 ; lt/91•tea spinifcm, Turton, Iliv., p. 133. Shell somewhat subtriangular, subcomprcssed ; umbones small, acule, ami slightly inllectcd ; posterior or cartilage side nearly parallcl ; anterior side rather concave ; surface with many fine, conccntric, sharp, almost equidistan!, elevated, slightly rcllectcd, laminar ridges, which on the margin of the cartílago side become conlluent, in pairs, and projcct in the form oí a series oí short, obtuse spines; between these two ridges of spincs there is an elongatccl, subulate, deep, obliquely strinted cavity, for the rccept ion of thc ligamcnt; at the t ermi- nation of these ridges oí spincs, the shell is slightly truncated; the intercostal spaces are finely and very minutcly striated transversely, which can only be sccn by the aid of a lens; inside smooth, yellowish-white; margin somewhat llattenecl, all(l plain. Found at Salcomb Ilay, D evonshire; severa\ parts on the \V estcrn coasts ; a ll(l nt Portmarnock, lreland, but is a very local and rare species. GENUS 21.-LUCINA.-Ilruguicre. Shcll equivalvc, inequilateral, usually orbicular, lenticular, niul subdepressed; teeth variable, most commonly two minute, cnnlinal teeth, dil'ergent from the umbo, frequently nearly ohsoletc; in 0110 valve one )al.eral tooth 011 each sicle of the 11mbo, ami two 011 each sicle in the other; the anterior lateral unes being situate near to thc primnry teeth, and the posterior immedintely behiml the lignment ; two muscular imprcssions, rcmote írom each other, thc anterior one generally extended hnckwards nnd downwards, in the form oí an clongated band ; pallial impression clcstitutc of n sinus ; lignment externa), elon- gated, ancl partly hiclclen by the inllectecl margins of the l'alves wheu closecl, consequent ly the interna\ tendinous portian is fre- c1uc11tly sunk into a clecp, clongatecl cavity, si tuatc betwcen the teeth ami hinge margiu. The Lucin.u inhabit the ocean. Fossil specics are numcrous, ali(( occnr in the bcds of the Tertiary formation, of which they are a characteristic type. l. Luc1:-A 1uouL,1, pi. XXXIX, f. S, 9. L 11ci11a rnclu{a, First Ecl., pi. l i, f. 8, 9; Lamarck, V, p. 5·1 1 ; Fleming, p. •1·11 ; F orbcs, p. 47 ; Tclli1w radula, l\Iontagu, p. ü8, ¡1I. 2, f. 1, 2 ; Maton ami Hackctt, p. ,5-1; f/cm1s bo1·calis, Donovan, IV, pi. 130. Shell suborbicular, com·cx ; umbo central, small, slightly pro- duced, blunt, a little inílcctccl; lunule oblong, cordiform, nrnch depresscd; posterior side with a longitudinal flexure, emanating behind the umbones, nnd tcrminating on the side; whole exterior covered with numerous, fine, di,tant, ele,·ated, con- centric, narrow, laminatcd ribs, which are sharp 011 the s urface, and fcel rough to the touch, white, or coverecl with a very thin, yellowish-brown epidermis; inside dull white, exccpl bctwixt thc pallial impression and the margin; sinus narrow, obliquing clownwards, ami nearly parallel with the margin ; hinge with two oblique teeth in both valves, c111c of them a Jittlc clcft. This shell is sometimcs elongat ecl in form, as in fig. 9, Not uncommon on many of the Ilritish and lrish coast;. 2. LUCINA R0TIJNDATA, pi. XL, f. 11. 11fysia rotwulata, First E<l., pi. 16, f. 11 ; L ucina 1·otundata, Turton, Iliv., p. 114, pi. 7, f. 3; T ellina 1·otimdat<t, Montagu, p. 7 J, pi. 2, f. 3; Maton and Ilackett, p. 56; Brown, 'W ernerian l\fom., U, p. 508; P sammobia 1·otundata, Fleming, p. 438. Shell thin, orbicular, white, and rather convex ; umboncs small, nearly central, oLtuse, and vcry slightly turned to one side; surfacc moderately glossy, with fine, uearly obsolete, con- centric striro ; insicle smooth, glossy, whitc; two tecth in each valvc, one of which is cleft, an<l thc othcr slightly divergen(. lnhabits the sea at Poole, D orsetshire; also the coasts oí Dcvon ancl \.Yales; and has been mct with on severa\ parts of the l rish const, particularly at Bantry Ilay. 3. LtJCINA LACTEA, pi. XXXIX, f. 3. Lucina lm:tca-, First Ed., pi. 17, f. 3; Lamarck, V, p. 542; Turton, Iliv., p. 11 2, pi. 7, f. 4, 5; 1'ellina lactea, l\fontagu, p. 70, pi. 2, f. 4; L oripes lacteus, L each, MSS., p. 9 ; F leming, p. 430. Shell thin, orbicular, equilatcral, com·ex; umboncs small, ncarly central, ami slight ly inlleclecl antcriorly, with a small corcliform lunule under them; surface white, with fi ne, con- centric, irregular wrinkles, sometimcs interspersed wi th a fcw anliquntcd ridges; inside white, modcrately glossy; hinge with two small t eeth in one valve, and one in the other; a dcep sulcus, by the side oí the tceth in both vahes, emanating at lhc umboncs, for thc reception of the cartilage ; margin below the pnllial impression shining, sligh t ly and obsoletely striatcd longitudinally. F ound nt Torbay, Falmouth, Kingsbridge, and Poole. ,1. LucJNA tJNDA'l'A, pi. XXXIX, f. 1, 2. L ucina mulata, First Ed., pi. 17, f. 1, 2 ; Lamarck, V, p. 543; Tmton, Iliv., p. 115; Forbes, p. 47; f/enus wu{ata, Pen- nant, I V, p. 95, pi. 55, f. 5 1 ; 11:lontagu, p. 117 ; Fleming, p. 148; Donovan, pi. 121; llfaton ancl Hnckett, p. 86; Mysitt u11data, L each, MSS., p. 9, Shell nearly orbicular, thin, flexous; umbones prominent ; beaks rather acnte, nnd slight ly inllccted ; destitule of a Iunule; surfoce of n pale, clull fawn-colour, or white, with numerous, fine, close-set, irregular striro, which in some instanccs run into une\·cn, irregular m inkles; hinge strong, with threc teeth in one \'all'c, ancl two in the other, t ite posterior one clcft; inside smooth, glossy; margin plain, with an acule edge; the sim1s in the pallial impression very largc, reaching nearly to the middle of the vah•es. Young shells are sometimes glossy externally. The rnricty, fig. 1, is from 13clfasl Lough, Ireland. Found on most of Ihe Dritish nml l rish coasls.