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

NA YADES.] MOLLUSCA. 79 l. ¡\ N0D0N CYGNEUS, A1wdm1!1t Cyg11ea, Lan1arck An. San Vert \TI 8·l D . , ' .. · ., , p. ~ ; ra- pernaud, H 1st. Nat. des Moll. p. 13'1 Jll ¡ ¡ f 6 ¡ ¡ J 9 f , • • , • , (111( p. -, . 1; Anodrm C1¡g111111s, Turton 13rit 13 1• 1• p 23"· illJ 1·t C • • ~ > • •• • ¡¡, 1 !J I IIS !J."- ?lCllS, l.1 11 11:cns, Syst. Nat., p. 1158; Gmclin ¡i. 3355 · Monta,,"u 'I' I' . ' ' º , cst. ,nt., p. 170. Shcll thin, oblong-ovate, lmnid; anterior side short rounded • . l , , posterior s opc c,lon:,:ated, all(l somewhat pointed, more or less angnlat ed, ami subcomprcssed; nmbones but slightly produecd, and place<! nearcst the anterior side. This species is subject to great varicty of form. These variclics ha\'C•, by different authors, been considered distinct specics ; hut we harn not been able to detect any specific dif- ference in the animal inhahitant. There are, however, se,·eral ll'CJl-marked ali(! permancnt varicties, the distinguishing charac- teristics of which we shall endeavour to point out. l\fost of the Anoclons undergo considerable change, in their progress from the young to the adult condition. Varit:l!J l. CvG1mus, pi. XXVIII, f. 1, 3, 4. A11odo11tc, Cyg11ea, Pfciffer, 1, p. 111, pl. 6, f. 4; Rossmassler, I, p. l 11, pl. 3, f. 67; lb., V, VI, pi. 25, f. 342; il1!Jlilus Cyg- neus, Pennanl, Brit. Zool., IV, p. 1 i 3, pl. 67, f. 78; Donovan, Brit. Sh., pi. 55 and 113; Maton and Ilackett, Linn. Tr., VIII, p. 109, pl. 3 A, f. 2; Sheppard, Linn. Trans., XIII, pi. 5, f. 3; Montagu, Test. Brit., p. 170; Fleming, Edin. Ency., VII, p. 96, pl. 205, f. 16; Thompson, Ann. and Mag. Nat. Hist., VI, p. 40; Anodon C!Jgnea, Alder, M.lg . Zoo). 311d Bot., II, p. 117, Shcll rnther thin, oblong-c,vate, iníl.lted ; umbo sm3JI, placed ncar the anterior side, which is roundecl and short; posterior side elongated, with the hinge line nearly parallel, or slightly obliqne, from whc,nce it sucldenly slopcs into a subrostrated form; lower margin rouncled, gradually sloping upwards towarcls the pos terior side; externa) surface concentrically wrinkled, ancl covered with an olive-green, shining epidermis; inside pearlaccous. Figs. 3 ancl 4, young shclls. Founcl in thc ril'er O use, at York; thc Thames, near \'V'ind- sor; in thc poncls at Elmingham Park, thc scat of the Countess of Dysart, Suffolk; Loch Kettrine, Scotland; in the Grand Canal, ali(! the Moyntaghs, County of Armagh, Ireland; and many other lakes ancl rivers in Britain ancl Ireland. Vm·iel!J 2. CELLENS1s, pi. XXVIII,* f. 1, 2. A11ocio11ta cellc11sis, Encyclopeclia Methodique, pi. 202; Pfeif- fcr, I, p. l 10, pi. 6, f. 1; Ilossmassler, IV, p. 23, pl. 19, f. 280; Anorlon cellc11sis, Alcler, l\fag. Zoo!. and Bot., II, p. 118; Ano- don Cygncus, Drapernaud, Moll., pi. 12, f. 1; Turton, l\fan., pi. 1, f. 8; Anoclon pal1'dosus, Turton, Brit. Biv., p. 240, pi. 15, f. 6; Anorlonta sulcala, Lamarck, An. San. Vert., V, p. 85; 11/ytilus cellensis, Schroeler, Flussconch., pi. 2, f. 1 ; Mytilus · cmatilms, Pennant, Brit. Zoo!., IV, p. 113, pi. 68, f. 79; Maton and :Rackctt, Linn. Tr., VIIT, p. 110, pi. 3 A, f. l; Montagu, Test. 13rit., p. 171 ; Shepparcl, Linn. Trans., XIII, pi. 5, f. 5; Fleming, E<lin. Ency., VII, p. 99, pi. t04, f. 14. Shell considcrably elongatecl, with numerous, concentric, and rathcr dcep wrinklc~; hinge line ancl base nearly parallel to each othcr ; anterior siele short; posterior side ,•ery long;' the upper ami under sides both sudclcnly contracting into a sub- rostratccl form ; corcrcd with a grcenish, shining epidermis. This variety differs from the Cvgneus, in its form being much more lengthened, and in the hinge and basal lines bcing both nearly straight, ancl almo~t parallel to each other. Fig. 2 reprcscnts the young shell. This shcll varies consiclerably in size in different localitics. It has bcen found in the pond of my friend Thomas Glol'er, Esq., at Smedlcy Hill, near Manchester, measuring thrcc inches and a quart.cr in length, ami six ami a half in breaclth. Found in the pond of the Infirmary, i\1a1,chester, ancl in many othcr ponds in thc neighbourhood; Borrodalc, \Vcst- moreland; Loch Vcnnachar, Pcrthshire; the loch ami ponds at Duddingston, near Eclinburgh; ami in the Grand Canal, near Shannon Harbour, King's County, Ircland. This variety is more commonly diffuscd throughout Britain than any of the others. Vc11·íety 3. ANATINA, pi. XXIX, f. l. Anoclo11tci .A11ati11a, Lamarck, An. San. Vert., VI, pt. 1st, p. 85; Pfeiffer, I, p. 112, pi. 6, f. 2; Ilossmassler, V, VI, p. 57, pi. 30, f. 417 to 420; Thompson, Ann. ami Mag. Nat. Hist., VI, p. 55; Alder, l\fag. Zoo!. and Bot., II, p. 118. Shell thin, subcompressed ; anterior sidc Ycry short, nncl rounded; hinge linc abruptly ascencling into nn acule angle, and suddenly desccnds in a hollowcd liuc to a somcwhat trun- catcd beak, which is a littlc produccd al its lower anglo; from the anterior sidc the basal line suddenly clescends in n rounded form, and again mnkes an acule upwards angle, to mect thc posterior line; outer smface covercd with a shini11g, fresh-green epidermis. The posterior side of thc shcll is very long, and much broader than in any of the former varieties. This l'ariety is easily clistinguished from its congcners, by the posterior side being much broader than any of them, and from thc very abrupt upwards anglc of the hinge line. A modifica- tion of this variety occurs in thc river Cam, near Cambridge. It is considerably more inílated than thc ordinary form of A11ati1111s, and is of a small size. Its length is ono inch nnd thrce-quarlers; its brcaclth three inchcs and a quarlcr; and its thickness one inch and one-eight.h. Found at Southport, Lancashirc; Loch Leven, Kinro~sshirc; Prcstwick Carr, Northumbcrland, where we obtained the bcau- tiful and highly charactcristic spccimcn from which our figure was takcn; ami also in the rivers Shannon and Bresna, and thc Grand Canal, Irelnncl, Va,·iet!J 4. STAGNAL!S, pi. XXVIII, f. 2, jJf!Jtitus stag11alis, Sowcrby, Drit. l\facell., pi. 16 ; .M9tilu1 C!Jgneus, Maton 311d Rackett, Linn. Tr., VIII, p. 109; Mon- tagu, Test. Drit., p. 171. Shell thin, much inílated; umbones subcentral; anterior side roundecl, with a slight angle above; hinge line arcuated; poste- rior side slightly hollowcd, and lerminating in a subacutc benk; basal linc nearly semicircular; outcr surface with an olivaceous, shining epidermis; vcry pcarlaccous and iridescent internally. In the young<,r condition, thc colour is of a bright yellowish- green. Found in the pond of Kew Garden; in the Canal Wharf al Bolton Bridge, Lancashire; and in the canal at Kcighley. Va,·iel!J 5. INTERMEDIA, pi. XXX, f. 5, 6. A11odo11ta i11te1·media, Lamarck, Hist. An. San. Vert., VI, p. 86; Pfei[cr, I, p. 113, pi. 6, f. 3; Aldcr, Mag, Zool, and Bot., II, p. ll8.