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

PECT!NIDES,] MOLLUSCA. il l. ÜSTI\EA El)U!.!S, pi. XXIII, f. J!), ali(! pi. XXX; ; f. G, 7. Ostrctt edulis, First Ed., pi. 31, f. 19; Linné, Syst., p. 11'18; Lamarck, VI, p. 205; Pcnnant, p. 102, pi. G2, f. 70; Da Costa, p. 15-1, pi. 11, f. G; Montagu, p. 15 l. Shcll suborbicular, ruggcd, foliaccous, thc folds lying ovcr cach othcr in irregular arder; the poiuts of the u111baues apart from each olhcr ; lowcr valvc largcst, ami more concave thau the upper one; valves clo,e<l ali rouud; the externa! foliations frequently in the form of clivergenl, longitudinal, irregular, interrupted ribs, ami someti111es irregularly ami lransverscly striatc; margins of the valvcs slightly un<lulatccl; oulcr surface of a dull brown colour; iusi<le white. This shcll is liable to great varicty, both in size and form ; those founcl at Carrickfcrgus, in Ircland, are very largo and ponclcrous, generally measuring sevcn inchcs an<l upwards in cliamcter; while al Carlingfor<l ancl Milford thcy are vcry small. They iuhabit many of the coasts arouncl Britain and Ireland. Fig. 19, pi. XXIII, is from the Frith of Porth; it is a lusus, with a singular prolongatian of thc hinge. Fig. 6, 7, pl.·XXX,* is fram l\'lilford, and is thc ordinary sizc of that locality; this varicty is providcd with a row of tceth- likc proccsses, divergiug on cach sidc of thc umbo, which is rathcr acule and triangular. 2. ÜSTI\EA PAI\ASITICA, pi. XXIII, f. 20, 21. Ost,-ca pai·asitica, Chcmnitz, VIII, p. 19, pi. 71, f. 660; Turtou, Biv., p. 205, pi. 17, f. 6, 7; Plcmiog, p. 392. Shell small, thin, longitudinal, seldom exceeding two inchcs; of a drab or grccuish-browu colour; somclimcs with radiations of black ar brawn ; beaks gcnerally incurvecl; surfacc usually smooth; insidc white, with slight pcarlaceous rellectians. This species is invariably allached to other bodies, and sub- jecl to great variely in form, depending upon the substance lo which it is fixcd. It is met with on sorne coasts adhel"Íng to stones, rollen wood, &c., near low water-mark. I found severa! specimens altachecl to a piecc of rollen wood, at Hull. I do not believe thal ali the young of the O. eclttlis are parasitical, as sorne authors imagine. FA~IJLY III.-PECTINIDES. Shell generally regular, and nat foliaceous; ligamen! placed interiorly, or partly so. GENUS 5.-PECTEN,-Bruguicre. Shell inequilateral; thc uncler \'ah-e generally more convex than the upper one; subequila1e·ra1, with many groovcs or ribs, ra<liatiurr from the umbones to the margins; provided with two auricles~which are, for the most pnrl, irregular in size, <:lose below one of them in the uppcr vnlve is a small notch for the passage of the lyssus; m~scular ~mpressi?n large, p~aced so_me- what to one side; pallicl 1111prcss1on dcslttute of a smus; hmge linear, without teeth; lignment consisting of three porlion~, of which the two lateral pnrts are elongated, all(l follow the hmge line, the third portion thick and triangular, nnd fitted into a tri- angular shallow pit within the hingc. Scclion I.- O11c 1:ali:ejlat, tl1c othei· clcep a11d co11vc.i-. ]. PECTEl\" MAXD!US, pi. XXV, f. J. P cctc1~ 11w:1:imus, First Ed., pi. 32, f. 1 ; Lnmarck, VI, p. 163; Moutagu, p. 1'13; Fleming, p. 383; Turton, Biv., p. 20i; Forbcs, p. 3!); Osfrca ma:t·iinn, Pennnnl, IV, p. !)!), pi. 5!), f. 61 ; Donovan, pi. '19; Brown, \ V ernerian Mem., II, p. 513; Ih., Ene y. Brit., p. '11 i. Shell suborbicular; upper valve com•ex; the uncler llat, shorler than the other oue, and depressed ncar the umbo, in which situation thc ribs are nearly obsolete, all(I dernicl of striro; each valve provicled with fourlcen or fifteen roundccl, gently undulating, <livergent ribs, with obsolete oncs 011 both si<les ; the whole of which, togelher with the intersticcs, are CO\'erecl with very slrong, irregular, <li\·ergent strin, ; entir<> surface invested with fine, concentric, undulatiug striro, and inequidistant, remole lines of growth; provided with two ncnrly equal, rectangular amieles, covered with narrow, rather closc, roundcd, diagonal ribs, these are crossed by uumerous, thick- set, undulating, longitudinal striro, and inequidistant lincs of growth; whole surfacc of a reddish-brown colour; inside white, wilh flattcnecl, broad ribs, ali(! a rufous-brown, ve1·y broad, ill clefine<l fillet rouncl thc margin, which is very slightly scalloped. Length five inches ; breadth six inchcs. Founcl in deep water on many of the British coasts, namely, Dorsetshire, Devonshire, ali(\ Northumberland; Dublin llay, Porlmarnock, Lough Strangford, and llray, Ireland. 2. PECTEN J AC0HJ"EUS, pi. XXIV, f. 5. P ecten Jacobtcus, First Ed., pi. 33, f. r,; Lamnrck, VI, p. 163; Turton, p. 20i; Pennant, IV, p. 100, pi. GO, f. 62; Fleming, p. 383; l\'Iontagu, p. 144 ; Ost1·ca Jacoba:a, Donovnn, pi. l 3i; llrown, Ency. !hit., ]>· ,117. Shell with seventeen or eighteen very canvex, divergenl ribs; the upper valve llat, rufous, with rounded ribs, ami a smooth whitish depression near the umbo, in which situation the ribs are nearly obsolete; under valve very com•ex, pure white, pn\e brown, or llesh-coloured; ribs angulatecl, rising abruptly at the sidcs, ancl gently rounded on the surface, the interstices with strong, inequidistant, longitudinal furrows, usually three lo each rib, the central one being considerably broader than the others, and crossed by fine transverse striro; amieles equal, rectangular, wilh nearly obsolete, diagonal ribs, two or three of which are stronger Lowards the hinge linc, or top of thc auricles, thesc are crossed by extremcly fine, somewhat irregular, waved striro, and striatcd; inside white, slicthtly tinrred with a redclish hue near the margin, which is sc;lloped. 0 Length three inches; breadth four inches; but" is found much largcr in thc Bay of Naples, and other continental localities. Dredged in deep water off Poole and Weymouth, Dorset- shire; Cornwall; and al Scarboraugh, Yorkshire. It is, how- ever, a vcry rnre Dritish s:pecies. Section I I-Both valves convez, and equal in size; auri- cles 1111eq11al. 3. PECTEN 0PERCULAI\IS, pi. XXIV, f. l. Pecten ope1·c1da1·is, First Ed., pi. 33, f. 1 ; Linné, Syst., p. l 1'1i; Lamarck, VI, p. Ii2; Montagu, p. 145; Turton, Biv.,