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

96 MOLLUSCA, [CONCHACEA, The want of crenulations on tite margin of this shell, will at once distinguish it from thc C. Dan111onie11sl$, Found on the coast of Cailhness, and lhe Frith of Forlh, Scolland; and the Downshirc coasl, lreland. 3, Cn.i.sSINA ELLIPTICA, pi. XXXVIII, f. 3. C1·assina elliptica, Firsl Ed., pi. 18, f. 3. Shcll thick, nearly oval, rathcr comprcsscd; umboncs pointed, considerably turned towards the anterior side; benealh which is a cordiform, deep lunulc; cartilage side rather straight; with many regular, lransverse, ncarly straight., obsoletcly slriale ribs; oxternal surface of a dark yellowish-brown; inside white, smooth ; margin plain, ralher thickencd, with a slight rim at the edge. Found in the Frilhs of Forth ancl Clyde, The more lhickened margin, ancl clliplical form of this shell, will al once distinguish it from its congeners. 4. Cn.i.ssINA 0VATA, pi. XXXVIII, f. 11, 12. Crassina ouata, Brown, Edin. Journ. Nat. ancl Geo. Science, I, p, 12, pi. 1, f. 8; Crassinci Gaircnsis, Nícol, MSS. Shell thick, strong, subcompressed; umbones small, pointed, wilh a lanceolate, cleep, nncl large lunulc bclow lhem ; surface of a deep burnt umber-brown, wilh numerous, broad, clcvaled, concenlric, transvcrsc ridgcs, which become nearly obsolcle ns lhey approach lhe base of the valves; insidc bluish-white, with a broad and plain margin; muscular imprcssions large nncl deep. This species hns much lhe appearnnce of C. S cotica, but cliffers from it in being more ovale, much slronger, lhe mus- cular imprcssions being uearly double the size, and in lhe lunule being largcr ancl deeper. Inhabits lhe Gair Loch, in lhe river Clyde, where il is rather plenliful. 5. CnASSINA SULCATA, pi. XXXVIII, f. 10. Crassina s1dcata, First Ecl., pi. 18, f. 1O; Venus s1dcata, Mon- tngu, p. 131; Lanmrck, V, p. 592; Maton nncl Racketl, p. 81, pi. 2, f. 2 ; Brown, Werneriam l\lcm., II, p, 51 O; Asta,·tc sul- cata, Flcming, p. 439, Shel\ slrong, thick, suborbicular, subnugular, and considerably compressecl; umbones very promincnt, nearly central, acule, nnd but slightly lumed to one side, with a lanceolate, shal\ow lnnule; externa! surface of a yellow-cheslnut, strong epidermis, ancl a series of ,·ery broad ancl flat lransverse ridges, which become ncarly obsolete at the siclcs, ancl towarcls the umbones; cartilage side somcwhnt llattcnecl; basal margin well roundecl; inside smooth, white, ancl very glossy ~rom the pallial imprcssion to the margin, which is vcry flncly crenated at the cdgc; hinge teeth very strong. Length about se\'Cn-eighths of an inch; breadth not quite so much. This shell is Yery clistinct from its congeners; the t rnns\·crse ridgcs are grently broader, ami very much deprcssed; the space between the pallial imprcssion much broader and flntter, nnd thc epidermis more clear. T'.1rton has complctely mistaken this \·ery dislinct. spccies, in quotmg Montagu. His dcscription ancl figures apply to C. Dan- mo11ie11sis, from which thc prcscnl is totally clistinct. Found in Orkney ancl Cornwall; ami has been dreclgcd nli\'e al Bray, Irelancl. I mct wilh odcl Yah-es in lhe Frilh of Forth and on the bcach at Montrose. ' 6. CnASSINA coMPRESSA, pi. XXXVIII, f. 4, 5. Crassina comp,·essa, Firsl Ed., pi. 18, f. 4, 5; Montngu, Sup., p. 43, pi. 26, f. 1, 1, l. Shell slrong, thick, ncarly orbicular, compressed; umbones promincnt, turncd slighlly to thc anterior side, bcneath which is a cordiform lunule; surface with a fcw irregular, remole, concentrie wrinkles, which becomc obsolete towards the base of the valves; of a clark umber-brown colour, beneath which the shell is covered with transverse, irregular, almosl obsoletc striro; inside smoolh, white; margins broad, flat, ancl lhin, and destitule of crenulations. This specics diffcrs from any of the preceding, in bcing des- tilute of distinct ridges, and is more orbicular. The young are of a pale yellowish-brown, ami are almost smoolh, but when the epidermis is removed, they bctray a finely striatcd surface. I obtained some live spccimens, by dredging, off the coast of Dunbar. The only foil grown specimcn which I havc scen, is that from which Montagu's shel\ was dcscribed and drawn, as well as my figure, .and is in lhe cabinet of my late fricnd David Falconcr, Esq., of Carlowrie. 7. CnASSINA connuGATA, pi. XL, f. 24. Crnssina co,.,.ugata, First Ed., pi. 16, f. 24. Shcll strong, somcwhat triangular, compresscd; umbones small, oblusc, ami very slightly reflexecl; benealh thcm a largc, deep, lanceolatc lunule; surface CO\'ered with a rcddish-brown epidermis, lrans\•ersely wrinkled, ami wilh ncarly obsolcte, transvcrsc, numerous, irregular slriro; inside smooth, bluish- while; margin smooth, and cntire, sloping gradually towards the centre, but not deep; teeth ve1·y slrong. Length an inch anda half; breadth nearly two inches. This shell differs from the other specics, in the posterior mnrgin bcing somewhat produced, ancl in its total destitution of ribs; al!(! is much ílatler, in proportion to its size. Discoverecl at Grecnock, by my friend Stewart Ker, Esq. 8. CnASSINA DEl'IIESSA, pi. XXXV!If, f. 2. Cmssimt clepressa, First Ecl., pi. 18, f. 2. Shell compressed, lransverscly ancl obliquely subovate ; um- boncs rathl?r promincnt, ami slightly reflexed, with a lnnccolatc, decp lunulc under them; colour of a dark reddi$h-brown, with many llattened, frnnsvcrse ridges, ancl narrow, shallow, inter- vcning furro\\·s; insicle white, smooth; margins plain, and rather thickened in the erige. Lenglh nine-cighths of an inch; breadth ncarly eleYcn-cighths. This differs from the C. Scotica, in being more transvcrsely clongatccl, obliqne, more compresscd, with thc basal linc more paral\cl, the transverse ridges more numcrous, Ycry flat, and almost obsoletc. Found in the Frith of Forth; but I ha\'e hithcrto only met with clend ancl cletached vah·cs. 9. CllASSINA STlllATA, pi. XXXVIII, f. G, 7, 8. Crassinct sfriata, First Ecl., pi. 18, f. 6, 7, S. Shell suborbiculnr, ,·ery strong, ancl ralher ,·entricose; um- bones procluce_d, ancl rnlhcr blnnled al thc bcaks, placed ncarly central, ancl sl1gh1~y reclining; licncath them a dccp, lanccolat e lunulc; surfocc \\'lth nnmcrous, regular, fine, trausYersc stri:c, co,·crccl with a clark olirn-hrowu epidermis; iu, icle whitc, smooth'. ami glossy: cartilagc impressions vcry dccp. Lcngth three-e1ghths of an 111ch; brcaclth half an inch.