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

J\'I YTILACEA.] MOLLUSCA. i5 Shell smooth, ~r provicled with a fow scalcs near the margin, generally of a un1form, <lull greenish-brown, with palc pmple rays; beaks scparnte<l by a linear, transverse cavily; insidc pcarlaccous, and glossy, except round the margin, which is dull, an<l extremely thin; hinoe with a sinolc sm•ll denticle which o o ' 1,1, ' fits into a slight hollow in thc oppositc vah·e. Length an<l brcadth uearly equal. First discovere<l in Bantry Day, by I'l-liss I-Iutchins, an<l afler- war<ls foun<l by Dr. Turton in Dublin Day. GENUS 8.-CnENATULA.-Lamarck. Shell subequivalve, compresse<l, somcwhat distorted, and )a- mellar; hinge lateral, linear, marginal, and internally crenulatcd; the crenulro placed in a continuous series along the hinge, cach of them prcscnting a small rounded callosity, and excavated for the reception of part of the ligament; muscular impressions almost obsolete, of an oblong form, and situate near the ante- rior margin of the pcarlaccous substance. l. CnENATULA TnAv1s11, pi. XXIII, f. 20. C1·enat·ula Travisi·i, Turton, l\'Iag. Nat. Hist., VII, p. 350, f. 4i. "Shell rhombic, roundccl below, transparcnt, whitish, with pale violet, longitudinal, interruptcd stripes; the anterior mar- gin incurved; ncarly an inch long, and full half an inch broad; cxtrcmcly thin and brittle; obliqucly truncate at thc top, with a fow pal e violet spots below; hollowed out at the front margin in a slight crcsccnt-shapcd form."-Ttwton. Takcn alivc at Scarborough, by Mr. Bcan, ami is in his cabinet. GENUS 9.-CnENELLA,-Brown. Shell oblong-oval, equilatcral, ventricosc; bcaks obtuse, slightly turned to one side; hinge dcstitute of tecth, but with a flattcncd, horizontal, slightly crcnated plate on one side of the hingc in each valve; right valvc with a triangular, horizon- tal, projecting, reflexed plate, ancl the left one with an oblique plait, both of which are a littlc crenatecl externally. l. CnENELLA ELLIPTICA, pi. XXIII, f. 12, 13, 14. C1·enella clliptica, First Ed., pi. 31, f. l 2, l 3, 14; J elfreys, l\fal. ancl Conch. Mag., No. 11, p. 45; Brown, Conch. Text Dook, p. 143, pi. 18, f. 13; Jl/ytilus decussatus, Montagu, Sup., p. 69; Laskcy, Wcrncrian Mcm., 1, p. 394, pi. 8, f. 17; Flc- ming, Brit. An., p. '11 l. Shell longitudinally ovale, vcntricose, thin, ancl pellucicl; umbones acule, turned to one side; sides equal, rounded; covered with a pale olive-green epidermis; with fine, regular, divergent striro, allCI crossecl by very minute, equidistan!, con- centric slriro, ancl a few distant lines of growth, producing a fine decussated appearance when seen under a strong lens; beneath the epidermis the shell is white; inside smooth, exhibiting nacred reflections, the margins finely crenulate<l. Length an eighth of an inch ; brcadth not so much. Discovered by Caplnin Laskey at Dunbar; I dredged it in the Frith of Forlh, opposite Portobello; it has bcen also found at Zetland, and the coast of Argyle; and J. G. Jelfreys, Esq., met with it at Lerwick Sound, in 1841. FAfüLY II.-MYTILACEA. Hinge with a linear, suhinterior, marginal ligamen!, 1·ery entire, ancl occupies a considerable portion of the anterior mar- gin ; shells gcnerally foliaceous . GENUS 10-PINNA-Linurous. Shell equivalve, longitudinal, oblique, wedge-shnped; beaks forming an elongated point; posterior side gencrally truncated, and always gaping; the base ami anterior margin forming toge- t.her a straight line, the !alter gaping a little in the centre for the passage of the byssus; hinge without leeth ; ligament mar- gin greatly lengthened and linear, and coutinuing along the whole dorsal region ; two muscular impressions in each val\'c, the posterior one very Iarge, almost central, the anterior one ter~1inal, and sornetimes double; pallial impression dcstilute of a smus. l. PINNA INGENS, pi. XXVI, f•. l. Pinna ingens, First Ed., pi. 30, f. 1 ; Pennant, IV, p. 115; Montagu, p.180 and 583; lb., Sup., p. 72; Brown, Ency. Brit., VI, p. 424; lb., Wcrnerian Mem., 11, p. 51 G ; l\faton allCI Rackett, p. 112; Turlon, Biv., p. 221, pi. 20, f. J; Pbma frngiles, Turlon, I3iv., p. 222, pi. 20, f. 20; Fleming, p. 40G; Pinna lcevis, Donovan, pi. 152. Shell nearly straight from the beak along the hinge line, slightly turned inwards at the apex, ami connected the whole length, very ruggecl, foliaccous, with irregular, concentric wrin- klcs emanating from the beak al the open sicle, and running lengthways, turn to the hinge at nearly right angles; sorne- times in the form of interruptecl laminro, or pintes; a fow interrupted, longitudinal striro rise from the beak, crossing the wrinklcs, and sometimes forming on the broader portions of the shells, a fcw remole concave spines; oppositc side concnve, or indented, swelling out gra<lually at the larger end, where the valves are always separated, leaving a gap between them; basal margin irregularly waved; externa) surface of an opaque, dull horn-colour, frequently inclining to umber-brown; sorne- times of a blue cast towards the smaller end; inside smooth, glossy, of a dark pearlaceous lustre, and a little lamcllated towards the beak. This species grows to a large size, being not unfrequently upwards of twelve inches in length, and seven inchcs in brendth at the basal cnd. Found in the Hebrides; Salcomb Bay, Devonshire; and found at Portrush, County of Antrirn, Irelnnd, by Mrs. Clew- low, of Belfast. They are found in gravelly boltoms, among mud, standing upright, the smaller end being downwards, and firmly allached to their habitat by a brsus of long silky fila- ments: of a dark purplish-brown colour, two or three inches in length. 2. PINNA FilAGILJS, pi. XXVI, f. 3. Pinna pectinata, First Ed., pi. 30, f. 3; Pinna fragiles, Pennant, p. 114, pi. 59, f. 80; Fleming, p. 406; Pinna pecti- nata, Montagu, p. 178; Brown, Ency. Brit., VI, p. 424; Tur- ton, I3iv., p. 223, pi. 19, f. l. Shell subpellucid, thin, brittle, of a light horn-colour, sorne- times greenish, but darker towards the beaks; surface with about eleven longitudinal, narrow ribs, cmanating from the apex, and extending to the basal margin, thcse are beset with