CONCHOLOGY. 



18 



plan.itian. The \\i->,.(!nb!um,) (Imply, is the mere outer 

 contour of the mouth or ;ipemire ; but tne inner, or co- 

 lumella lip, (labium iiiterius -vel columella,) is the polilhed 

 or (niooth part oppofite to the lip, and is always Ipreacl on 

 the coiumt-lla. , j /• j 



The beak, (rojlruin,) is that prolonged and furrowed 

 part, extended Itraight upwards from tl.e top of the aper- 

 ture like a horn, moreorlcfs in the difterent families. It 

 is by feme authors called the tongue or bore, cfpecially 

 when fpoken of the pnrpurae; as it is imagined they bore 

 through the ftiells of the fi(h they feed on, with this ap- 

 tiendajre. , ,., 



The fcoon, (fmit!,) is the hollowed or gutter- like pro- 

 cefs placed tideways of the beak, and lower down on the 

 very lip: which is peculiar to the fj.iders, &:c. buch 

 (hells have been called, from thefe two-fold pioceffes, the 

 beak and fcoop, biicdna biiinguia. 



1 lie claws or prongs, (-/isit', daByh, unguh, or apfen- 

 AUcs,) are the jjrocefTes that illue from the contour of the 

 lip, as in thefpider-fhells. 



Umbilicated Ihells, (cocklea umbilicata,) are tJiole that 

 have a navel or hollow on the liill or body whirl, or in 

 the center, which penetrates tlie (liell deeply, or its length. 

 This is moltly fern in cochlea, trochi, and forae buccina. 



The helix, or helices, are thole (hells thai; have their 

 whirls or turnings King, as it were, between two flats or 

 levels, as fome river Aiails, poft-horn fnails, ammunits, 



and others. , ■ , ■ . 



Revolved fhells, (uni'vaMa turbinata, davicula mlus re- 

 c^i'dita, 'Vtl ita infe contort a, ut eonim circum'volutwnc! nulla 

 ex parte fnmineanl,) are thole that turn or revolve with- 

 indde, or whofe whirls or turnings are hidden orablorhed 

 within the body of the Qiell, fo that only the outer whirl 

 is fetn, and they have no clavicle: luch are the nautili 

 and the cowries. 



Winged ihells, (alatit,) are tliofe whofe lips expand 

 greatly outwards, and form large flaps or wings ; as the 

 plough, the duck's wing, the fpiders, and many others. 



Right-handed fliells, (heterojlropha,) are inch whole 

 whirls, or convolutions, turn from right to left, or con- 

 trary to the molt general manner of turbinated univalves. 

 Operculated lliells, (cckhsoperculata:,) are fuch as have 

 a loole piece, which Ihuts up or covers the aperture or 

 mouth of the fhell, like a lid. So that the fhell really 

 contiUs of two feparate and very unequal pieces ; viz. one 

 piece fiat and fmall, the other large :md Ipiral; the for- 

 mer being the lid, the latter the fhell itfelf. None but 

 turbinated univalves have opercula or lids. Thefe oper- 

 tula are fmall, in companion to the fhells; and of dif- 

 ferent fubftances, as fhelly, leathery, or horny. This tex- 

 ture may be illulhatcd by the operculum, or lid, which 

 js conftantly found to iiiclofe the common perriwinkle. 

 They are alio of diftVrent forms, as peifeaiy round, fimi- 

 lunar, elliptical, oval, or very lengthened; and they are 

 generally wrought with a fpiral work, or with concentric 

 circles. The operculum, or lid, is always fixed on the 

 upper part of the pedeltal of the fifh. In fome at the 

 outer end or extremity, l"o that it retires confiderably 

 from the fliell when the animal moves. In others it is 

 placed at the inner extremity or root. The operculum 

 exaaiy covers or doles the fliell in thofe whole mouths 

 are round, fcmicircular, or oval, as the nerits, turbines, 

 purpura:, &c. but in thofe rtiells that have very lengthened 

 or narrow mouths, as the volutes, it is not eafy to con- 

 ' ccive what uie the opercula are of; for they feem not to 

 fhut or cover much above the fifth part of the mouth. 

 Yet furely all the opercula; ftrve as covers, and entirely 

 fliut up the filh; th.refore, though they do not feem to 

 fit the outer mouths or apertures of the Ihells, yet the 

 fifh retires within the fhells, fo far as to make it fit, or 

 clofe exa6fly to where he retires. The above applies only 

 to fea univalves, whofe opercula are a part of tiie animal, 

 and brought forth with it. The operculated land uni- 

 valves are very different; they form a new lid, or oper- 

 cuJam, every year, or oftener; aod that is only at luch 



times that the animals require fo (Vietter tliemfelves fron* 

 the injuries of the weather. It is c<;mpoled of a vilcous 

 matter, which ill'ues from the body of the animal, which 

 condenfes into a kind of toughifh coriaceous or leather- 

 like lubllance, and is pretty thick. This lid, or crulf, is 

 never attached to the body of the animal, as in the fea 

 univalves, but merely covers the mouth; nor is it ever 

 wrought with a Ipiral or with concentric circles, or, in- 

 deed, any other regular work. All fliell-like opercula 

 are of a calcareous nature, and difiblve in acids. It is 

 therefore that, when put in vinegar or other acids, they 

 move brifkly to and fro for fome time, by the ebullition ; 

 from which particular, among the common people fond 

 of curiofities, they have obtained the name of creeping 

 Jlones. The horny and leathery opercula rejet't acids. 

 They have a kind of greafmefs or unttuofit)', which, 

 when they are burnt, exhales a ftrong fniell, loinetinies 

 agreeable, but molt generally fcetid. The blatta byzan- 

 tia, conchylium, or unguis aromaticus of the ancients, 

 and greatly valued, till of late, in the Materia Meilica, 

 was cf this latter kind. It was called unguis, becaufe 

 imagined to refemble the talons of a bird of prey. Diof- 

 corides mentions two kinds; one from the Red Sea, white 

 and greafy, which was the luoll elteemed ; the pther black 

 and not ia large, which came from Babylon. Of later 

 times they have ufed indifferently the iinall round oper- 

 cula of purpurae, &c. by the name of blatta bvzantia. 

 When burnt they exhale a fmell Ibmewhat like that of 

 caltoreum, and their fmoke was held good for vapours 

 and the epilepiy, and in decoflions they were reckoned 

 laxatives; but at preicnt thefe medicines are defervedly 

 exploded. 



The mod general ftruiture of teftaceous animals is to 

 be attached to their fliells, and to be always fixed in them 

 by one or moi-e ligaments or mulcles. This fixation cer- 

 tainly aiifwers to reafon 5 for thele cieatures can never 

 be imagined to form their fhells, and augment them when 

 neceflary, had not the animal itielf a fixed and common 

 communication with its fliell, to tranfmit the proper 

 juices for the iucreale of it. Yet, however, it is averred, 

 that the fifli of three families are not always affixed by 

 mufcles to their (hells, anJ tholt .^ic the veiiiiiculi or fer- 

 pula, the dentalia, and the paper nautili. The paper nau- 

 tilus certainly appears not to be fixed by any one part to 

 its fnell, and is very frequently feen without it. The 

 filhermen mult be very expert to catch the fifh in its fliell, 

 becauli; they quit their fliells with fuch facility. The 

 dentalia are found floating, as it were, in their Ih.lls, no 

 ways fixed, but quite loole and free, like any thing in a 

 flieath. However, to reconcile this difi'erence, and, per- 

 haps, it is the real Hate of the cafe, it is reafonable to fup- 

 pofe that thefe animals are not abfolutely Icole from their 

 (hells, but rather that they are very flightly connected to 

 it ; and, perhaps, when the flielf is complete or full grown, 

 they detach themfelves from the mulcles. Analogous to 

 what loblters and other crultaLCous filh do when they calt 

 their yearly crulls ; that is, they detach the mulcles of the 

 old crulls, to affix them en their new ones. 



There is another oblervation to be made with regard to 

 vermiculi, or ferpulae, viz. that thefe teltaceous animals 

 border on, or conneiil fo clol'ely to, the corals, that it was 

 long before conchologifls could fix their limits, fb as to 

 pronounce definitively whether corals fhculd be ranked 

 as teltaceous animals, as Martini has done in fome parti- 

 culars ; or, whether the ferpula fhould be rather ranked as 

 corals, and expunged the teltacea. Linnasus has thought 

 it right to feparate them, and make the fijrpula and den- 

 talia teftaceous animals, and the corals a feparate and dif- 

 tinfit order. Another difpute remained long unltttled ia 

 regarded to the echini. The echini were very indefinitely 

 placed by naturalilts ; many ranking them as crultaceous, 

 many as teltaceous, and others as animals of an order 

 diltinft from either. Thus Lilter and Adanion take no 

 notice of tliem among the teltacea. Rumphius and Se. a^ 

 place them with the lea itars and cruftdcea. Linnaeus 



Clafles 



