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

'fUlllCOLARJA.] MOLLUSCA. 117 Shcll thin, brittlc, subopaque, trans\'ersely subovate, ami wedgc-shapcd when the valves al'C unitecl; broad ami wi<lcly gapiug at the anterior sicle, from whence it graclually clecrcascs until it reaches the opposite ext.remity, where the va\ves are closcly shul; anterior termination of the ,·alves with a small hut prominmll, terminal bcak; externa\ surfacc coverccl with a h rown or blackish-brown coating, irrcgularly wrinkled trans- n,rscly; umbones rather promincnt, a1H! obtuse, situatc ncar thc larger side, al the junction of thc valvcs on thc superior margin; hingc with an obscuro, laminar, transverso tooth in both valvcs. General length half an inch; brea<lth an inch. Turton mentions a varicty of about half thc ordinary size, but not differing in other characters, which is found bmicd in the back of old oystcr shclls. Inhabits rocks ami stoncs at Torbay, an<l is an cxlrcmely lora! spccics. GENUS 50,-XYLOl'HAG,\,-Sowerby. Shcll ncarly orbicular, cquivalvc, inequilateral, gaping in front, thc opcning with an angular tcrmination at lhc back; two sma\1, somcwhat triangular, calyxformc<l, acccssory valves placed o,·er thc anterior siclo of thc hinge, and a small looth lying closc to thc umbo within cach valvc, bcsi<lcs an interna\ rib running from thc bcak to thc basal margin, with a corrcs- ponding externa\ dcprcssion ; anterior muscular imprcssion sma\lcst, situate on thc superior margin, closc to thc bcak; posterior muscular imprcssion largc an<l oborntc. l . XYLO!'HAGA D0RSALIS, p\. L, f. 8, 9, 10. Xylophagct dorsalis, Turton, Biv., p. 16 and 253, pi. 2, f. ,1, ::; ; Flcming, p. 455 ; Tc,·cdo dorsalis, Turton, Conch. Dict., p. 185. Shcll with roundcd valvcs, but <lcstitutc of auriclcs, postc- riorly closc<l, ami providc<l with an interna\ rib; without a rcf\cctc<l, auriform proccss postcriorly; thc tcnnination plain, an<l roun<lcd; one valve furnishccl with a raisecl, curve el proccss, an<l a small, slightly cleft onc in thc othcr; insi<lc with a joint- ccl, longitudinal rib, corrcspon<ling to thc externa\ groovc. Found in a piecc of woocl, at Torbay, by Dr. Turton. GENUS 51.-DENTALIU~I.-Linmcus. Shcll tubular, open at both en<ls, arcuatccl, increasing in dia- mcter towards the anterior cxtrcmity, whcre thc apcrturc is largo ami roun<l; opcning of the ~ointccl cnd very smal!, and with a lateral fissurc in some spcc1cs; externa! surfüce ribbcd, striatc<l, or smooth, but ncver with annulations, 20 I. DENTALIUM ENTALIS, pi. LVI, f. 7. Dentaliwn e11talis, First Ed., pi. 1, f. 7; Pennant, 1V, p. 1,15, pi. !)O, f. 15·1; Montagu, p. 494; Donovan, pi, 48; I3rown, Conch. Text llook, p. 52, pi. !), f. 33. Tube slightly arcuatcd, tapcring, smooth, and glossy; frc- queutly with incqui<listant, circular, irregular wrinklcs, or linos of growth; of a ycllowish-whitc colour. Length an inch and a half; <liamctcr at largcr cn<l two-tcnths of an inch, smallcr ene\ about a twcnticth of an inch. Inhabits many of thc British an<l Irish coasts. 2. DENTALIUM DENTALIS, pi, LVI, f. 8. De11tali111n dentalis, First Ed., pi. 1, f. 8; Linn.cus, Syst. Nat., p, 1263, No. 785; l\íaton ami Hackett, p. 237; Montagu, p. 495, Tube slcndcr, subarcuatcd, ,·ery tapcr, tcrminating in a small point; surface with regular, close-sct, longitudinal striro; somc- times a fow annulations can be traccd al lhc wider end; colour whitc, but not glossy. Length balf an inch; diameter at the base ha\f a linc. Discovcrccl by Coloncl Montagu, al Falmouth an<l south coasl of Dc,·onshire, ali(] is a very local spcdcs. 3. DENTALIUM 0CTANGULATUM, pi. LVI, f. 2. Dcntalimn sti-iatum, First E<l., pi. 1, f. 2; 1Je11/(l{ium octan- g-ulatmn, Donovan, V, pi. 162; Dentalimn sti-iatulum, Maton ancl Uackctt, p. 238; l\íontagu, Sup,, p, 155. Tubc slrong, white, arcuatc<l, tapcring to a vcry fine poiut, and furnishcd with cighl slrong, longitudinal ribs, which gi,·c to thc base, or widcr end, an cight-siclcd appearancc ; thc ntersticcs bctwecn thc ribs are tristriatecl. Lcngth about two inchcs. A local spccics, found 011 the sands al Lclant, Cornwall; r mct. with a single specimen at Holy Island. ,1. DENTALIUM LABIA'l"UM, pi. LVI, f. ,1, 5. Dentalium labiatm11, Firsl Ed., pi. 1, f. •1, 5, Tubc strong, smooth, whitc, subarcuatcd, an<l truncatcd al thc smallcr end; apex closcd by a pcrforate<l, testaccous lid. I found severa\ specimcns of this shcll in Lough Strnngfonl, Ircland. Thcy are now in thc cabincl of Lady Jar<linc. 5. DENTAL!UM GADUS, pi. LVI, f. ] • Dcntalimn Gadus, Firsl Ed,, pi. l, f. l ; Montngu, p, 496, pi, 14, f. 7; Maton an<l Rackctt, p. 238- Tube subpelluci<l, glossy, snow-whitc, consiclcrably arcuatcd; conlracted towards thc largor cn<l, an<l tapcring to a vcry small point at thc othcr cxtremity, Lcngth about thrcc-cighths of an inch ; cliamclcr about onc-sixtecnth. Inhabits thc llritish Channcl, but is a very rarc spccies.