18 •/ CONCHOLOGY. 
planation. The lip, (labium,) limply, is the mere outer 
contour of the mouth or aperture ; but the inner, or co¬ 
lumella lip, (labium iuterius uel columella,) is the polilhed 
or finooth part oppolite to the lip, and is always fpread on 
the columella. 
The beak, (rqflrum,) is that prolonged and furrowed 
part, extended ftraight upwards from the top of the aper¬ 
ture like a horn, more orlefs in the different families. It 
is by loine authors called the tongue or bore, efpecially 
when fpoken of the purpuras; as it is imagined they bore 
through the liiells of the filh they feed on, with this ap¬ 
pendage. 
The fcoop, (Jtnus,) is the hollowed or gutter-like pro- 
cefs placed lidevvays of the beak, and lower down on the 
very lip; which is peculiar to the fpiders, &c. Such 
fiiells have been called, from thefe two-fold procelfes, the 
btak and fcoop, buccina bilinguia. 
he claws or prongs, (digit!, daSlyli , unguli, or appen¬ 
dices,) are the procelfes that ifluesfrom the contour of the 
lip, as in the fpider-lhells. 
Umbiiicated Ihells, (cochlea umbilicata,) are thofe that 
have a navel or hollow on the firll or body whirl, or in 
the center, which penetrates the lhell deeply, or its length. 
This is moftly feen in cochlea, trochi, and fome buccina. 
The helix, or helices, are thofe Ihells that have their 
whirls or turnings lying, as it were, between two fiats or 
levels, as fome river fnails, poll-horn fnails, ammonitas, 
and others. 
Revolved Ihells, (univalvia turbinata, cla<vicula intus re- 
condita,, <ycl it a in fe contorta , ut eorum circumvolutiones nulla 
ex part’e promine ant,) are thofe that turn or revolve vvith- 
infide, or whole whirls or turnings are hidden or abforbed 
within the body of the lhell, lo that only the outer whirl 
is feen, and they have no clavicle: fuch are the nautili 
and the cowries. 
Winged Ihells, (alata,) are thofe whofe lips expand 
greatly outwards, and form large flaps or wings; as the 
plough,""the duck’s wing, the fpiders, and many other?. 
Right-handed {hells, (heterojlropha,) are fuch whofe 
whirls, or convolutions, turn from right to left, or con¬ 
trary to-the moil general manner.of turbinated univalves. 
Operculated fiiells, (cochlea operculata,) are fuch as have 
a loofe piece, which lliuts up or covers the aperture or 
mouth of the lhell, like a lid. So that the lhell really 
confills of two feparate and very unequal pieces ; viz. one 
piece fiat and final], the other large and fpiral; the for¬ 
mer.being the lid, the latter the lhell itfelf. None but 
turbinated univalves have opercula.or lids. Thefe oper- 
cula are imall, in companion to the liiells; and of dif¬ 
ferent fubftanees, as fheily, leathery, or horny. This tex¬ 
ture may he ill nitrated by the operculum, or lid, which 
is conllautly found to indole the common perriwinkle. 
They are alfo of different forms, as perfectly round, fimi- 
lunar, elliptical, oval, or very lengthened; and they are 
generally wrought with a fpiral w ork, or with concentric 
circles. The operculum, or lid, is always fixed on the 
upper part of the pedetlal of the filh. In fome at the 
outer end or extremity, fo that it retires conliderably 
ftom the lhell when the animal moves. In others it is 
placed at the inner extremity or root. The operculum 
exactly covers or clofes the lhell in thofe whofe mouths 
are round, femkircular, or oval, as the nerits, turbines, 
purpurae, See. but in tiiofe Ihells that have very lengthened 
or narrow mouths, as the volutes, it is not eafy to con¬ 
ceive what ufe the ppercula are of; for they feem not to 
Ihut or cover much above the fifth, part of the mouths. 
Yet fureiy all the opercuise ferve as covers, and entirely 
ihut up the fish; therefore, though they do not feem to 
fit the outer mouths or apertures of the liiells, yet the 
filh retires within the liiells, fo far as to make it lit, or 
dole exaclly to where he retires. The above applies only 
to fea univalves, whofe opercula are a part of the animal, 
and brought forth with it. The operculated land uni¬ 
valves are very different; they form a new lid, or oper¬ 
culum, every year, or oftener j and that is only at fuch 
times that the animals require to llielter themfelves from 
the injuries of the weather. It is compofed of a vilcous 
matter, which iffues from the body of the animal, which 
condenfes into a kind of toughilh coriaceous or leather- 
like fubtlance, and is pretty thick. This lid, or cruft, j s 
never attached to the body of the animal, as in the )h\ 
univalves, but merely covers the mouth; nor is it ever 
wrought with a fpiral or with concentric circles, or. in¬ 
deed, any other regular work. Ali (hell-like opercula 
are of a calcareous nature, and dilfolve in acids. It is 
therefore that, when put in vinegar or other acids, thev 
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 rejeft acids' 
T hey have a kind of greafmefs or unduofity, which* 
when they are burnt, exhales a llrong fmell, fometimes 
agreeable, but moll generally foetid. The blatta byzan- 
tia, conchyliu.m, or unguis aromaticus of the ancients 
and greatly valued, till of late, in the Materia Medica’ 
was of this latter kind. It was called unguis, becaule 
imagined to referable the talons of a bird of prey. Diof- 
corides mentions two kinds ; one from the Red Sea, white 
and greafy, which was the moil eiteemed ; the other black 
and not lb large, which came from Babylon. Of later 
times they have tiled indifferently the fmall round oper¬ 
cula of purpurae, &c. by the name of blatta byzantia. 
When burnt they exhale a fmell fomewhat like that of 
calloreum, and their fmoke was held good for vapours 
and the epilepiy, and in decoftions they were reckoned 
laxatives; but at prefent thefe medicines are defervedly 
exploded. _ J 
The molt general ftrudture of teftaceous animals is to 
be attached to their Ihells, and to be always fixed in them 
by one or more ligaments or mufcles. This fixation cer¬ 
tainly anfwers to reafon 5 for thele creatures can never 
be imagined to form their Ihells, and augment them when 
neceflary, had not the animal itl'elf a fixed and common 
communication with its lhell, to tranfmit the proper 
juices for the increaie of it. Yet, however, it is averred, 
that the filh of three families are not always affixed by 
mufcles to their liiells, and thofe are the vermiculi orfer- 
pula, the dentalia, and the paper nautili. The paper nau¬ 
tilus certainly appears not to be fixed by any one part to 
its lhell, and is very frequently feen without it. The 
fitliermen mull be very expert to catch the filh in its fiiell, 
becaule they quit their Ihells with fuch facility. The 
dentalia are found floating, as it were, in their (hells, no 
ways fixed, but quite loole and free, like any thing in a 
Iheath. However, to reconcile this difference, and, per¬ 
haps, it is the real Hate of the cafe, it is reafonable to lup- 
pole that thefe animals are not abfolutely loole.from their 
Shells, but rather that they are very (lightly conneifted to 
it; and, perhaps, when the fiiell is complete or-full grown, 
they detach themfelves from the mufcles. Analogous to 
what lobllers and other crullaceous filh do when they call 
their yearly crufts j that is, they detach the mufcles of the 
old crufts, to affix them on their new ones. 
There is another oblervation to be made with regard to 
vermiculi, or ferpulae, viz. that thefe teftaceous animals 
border on, or conned fo ciofely to, the corals, that it was 
long before conchologifts could fix their limits, lb as to 
pronounce definitively whether corals fiiould be ranked 
as teftaceous animals, as Martini has done in fome parti¬ 
culars ; or, whether the ferpula fiiould be rather ranked as 
corals, and expunged the teftacea. Linnaeus has thought 
it right to feparate them, and make the ferpula and den¬ 
talia teftaceous animals, and the corals a feparate and dif- 
tindl order. Another difpute remained long unfettled in 
regarded to the echini. The echini were very indefinitely 
placed by naturalifts ; many ranking them as crullaceous, 
many as teftaceous, and others as animals of an order 
diftind from either. Thus Lifter and Adanfon take no 
notice of them among the teftacea. Rumphius and Seba 
place them with the lea liars and cruftacea. Linnams 
daffies 
