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

MOLLUSCA. [MYAR!A. anterior side truncated, with a shallow, oblique furrow running near to the hinge line, most deeply delined in the convex valve; basal line nearly parallel; surface of a sand-colour, strongly wriukled, and slightly and irregularly striatcd concen- trically; when vicwed through a lens prcscnting thc appear- ancc of shagreen, and fccls vcry rough to thc touch ; bchind the cartilagc side one valve tums upwards, ami embraces the edgcs of that opposite ; hinge with onc broad, vcry strong, thickened, complicated, bipartitc, horizontal, tooth-like platc in each valve, lo which the cartilage is attached, that of thc convcx valvc sunk bclow thc leve) of thc hingc linc, and in the flat valvc almost cntircly cxposed above it; insidc white, and glossy. Found on the Dcvonshire coast of a large siie, but is a vcry local species. 2. T111tACIA CONVEXA, pi. XLI V, f. 3. AnC1tinc, conve.i·a, First Ed., pi. l 1, f. 3; Turton, Biv., p. •14, pi. 4, f. 1, 2; llfga convc:m, \Vood, Gen. Conch., p, 92, pi. 18, f. l; Drown, Ency. 13rit., 6th Ed., VI, p. 40:1; Tlwacia convc.i·a, Lcach, MSS., p. 5; Amphidcsma conve:i:um, Fleming, p. 431. Shell subtriangular, vcry convex, and cxtremcly brittlc; um- honcs obtuso, placed nearly central, a littlc inflecled, and almost touching cach othcr; sides rapidly descending, the posterior one rounded, anterior one truncatcd ; thc truncation boundcd by an elcvalcd ridgc, which takes its risc from thc beaks, and ter- minales 011 lhe basal margin, which is a little arcuatcd; surface of a sand-colour, concenlrically wrinklcd, obsoletely and irregu- larly striated, ancl very indistinctly granulated; dentary platc obliquely cle1·ated, narrow, with severa) longitudinal furrows for the reception of the cartilage; inside smoot.h, whitc, or pale rcddish-brown. In lhe adult shell the umbones are so very contiguous, that they only permit thc vah•es to open to a small exlent, not more than half an inch. Found on the Devonshire ami \'Velsh coasts, anrl also in Ireland; aml odd valves are frequently met with al Cramond Islam!, Frilh of Forth; Turlon mentions Paington Sands. It is au cxlremely local species. 3. TURACJ.\ l'UilESCENS, pi. XLIV, f. 6. Am1tina villosiuscula, First Ed., pi. 11, f. G; llfacgillivray, Phi!. Journ., 1827, pi. 1, f. 10, 11; Anat·ina declives, Turton, Ilil'., p. ,17; Jllyci cleclivis, Montagu, pi. I, f. 2; Amphidcsm<, declive, Flcming, p. •132. Shell transl'crsely oblong-ornte, comprcssed, thin ; umbones placed lo one side; posterior sidc much roundecl; anterior side contracted, ami lruncatcd; an elevated ridge emanatcs from below thc umboncs, and terminales at the base of the lrunca- tion ; oue central, flat, transrnrse looth in each rnlve; externa) surfacc with a lino pnbesccnt appearancc, when viewed through a strong lens. Found in Dublin 13ay, lhe Dorselshirc coast, ami Frith of Forth. ·l. TURACIA 0\'.\TA, pi. XLIV, f. 4. Anatina ovalis, First Ed., pi. 11, f. ,1, Shcll tmns\·erscly ovale, subtriangular; umbones ncarly cen- tral, vcry o_btusc, and not inllecled; sidos almost cqually round, but very shghtly truncated on thc anterior oue; hinge with a narrow, transversc loolh; surfacc a little shagreencd, which, however, can only be seen by the aid of a strong lens; colour pale yellowish-while; inside white. I found this shell at Color Cols sands, Northumberlancl. lt may be mcrely an accidental variety of T. dcclivis. 5. TanAclA DIST0R'rA, pi. XLIV, f. 7. Anatiiza disto1·ta, First Ed., pi. l 1, f. 7; Turton, Div., p. 48, pi. 4, f. 5 ; illga distorta, Montagu, p. 42, pi. 1, f. l ; Amphi- dcsma clistortmn, Fleming, p. 432. Shell ralher convcx, transversely subol'ate, thin, fragile, rugose, and distorted, particularly towards the base of thc valves; umbones straight, placed consiclcrnbly to one side; shorter side well rounded, thc other considcrably acuminatcd; hingc with a broad, triangular, slightly hollow tooth in both vah•cs; inside white. Found at Plymouth, South Devon, and at severa) places on the Irish coast. 6. THRACIA TRUNCATA, pi. XLII, f. 28. Anatina tnmcata, Turlon, Dil',, p. 46, pi. 4, f. 6. Shcll convex, cuneiform, subquadrangular; anterior side dcs- cending in an acule anglo from the umbones, which are situate ncar lo that side; posterior side long, with lhe superior or hinge line very flat, ancl abruptly truncated; basal margin nearly parallcl; surfacc pale ycllowish-brown, transversely striate; leeth projecling somewhat obliquely inwards, Found in thc interior of rocks at Torbay. 7. TIIRACIA llREVIR0STRA, pi. XLIV, f. 11, 12, 13, 1'1. Anati,u, bi·cvirostm, Brown, Edin. Journ. Nat. ancl Gco. Science, I, p. 11, pi. 1, f. 1, 2, 3, ,1; JVaJm bi·cvfrostm, Gray. Shell vcry convcx, lransversely oblong-ovalc; posterior sido roundcd; anterior side abruptly tapering to an acuminated, abbreviatcd beak; umbones small, pointed, ancl slightly inílected towards the anterior side; exterior surfacc covered with a rich fawn-colourcd epidermis, wit h a slight metallic lustre, beneath which thc shell is proYided with nearly obsolete, transverse striro; hingc with one large, elc1•ated, rcenrved, cardinal tooth in the right vahe, which lits under thc eclge of the superior margin in the left ; cartilage lixed in central pits beneath the umboncs; insidc palo purple, darkcr towards the extremilics; ma:-gins plain. Length thrcc-cighths of an inch; breadth up- wards of half an inch. This intcresting spccies was discovcred in the Frith of Forth, by James Gerard, Ese¡.; and I aftcrwards met wilh it near Porl S1)alon. It is also said to havo been found on the Northum- bcrland coast. GE:-;us 38.-LEPTON.-Turton. Shell comprcssecl, transverscly elongatcd, or nearly orbicular, equivall'c, ancl slightly incc¡uilatcml, gaping a littlc at thc sidcs; umbones ncarly central, ancl very slightly inflecled; hinge of one valre with a central, ercct, primary tooth, situale bctween two hollows, from both sidcs of the hinge cmanatc a ncarly straight, transverso rib, lying a littlc way wi lhin the margin, upon cach of which rcsls a small tooth-like process, not very remole from lhe hingc, lhe rib 0 11 onc of the sides is furnishecl wilh a small, interna), obliquc, spoon-shapcd cavity; the othcr v~ll'c is dcslilutc of primary teeth, but with a large, central, lrrnngnlar hialus for thc reception of lhe toolh of the opposile valve ; 011 cach sido of which are lateral tceth, cleft thcir wholc