CONCH' 
number of little prifins, placed in all kinds of directions, 
winch refraft the rays of light, and produce all the 
changes of colour obfeivable in thefe (hells. 
With refpeCt to the figures and colours of (hells, it is 
obferved, that river (hells have not fo agreeable or diver- 
(ified a colour as the land and lea (hells; but the variety 
in the figures, colours, and other characters, of fea (hells, 
is almoil infinite. The number of diltinCt lpecies we find 
in the cabinets of the, curious is very great; and doubt- 
lefs the deep bottoms of the fea, and the (hores yet un¬ 
explored, contain multitudes (till unknown to us. Even 
the fame fpecies differ in fome degree in almoft every in¬ 
dividual; fo that it is rare to find any two (hells which 
are ftriCtiy alike in all relpeCts. This wonderful variety, 
however, is not all the produce of one fea, or of one 
country; the different parts of the world afford us their 
different beauties. Bonani obferves, that the moll beau¬ 
tiful (hells we are acquainted with, come from the Eaft 
Indies and from the Red Sea. This is in fome degree 
countenanced by what is found to this day; and, from 
the general obfervations of the curious, it feetns, that the 
fun, by the great heat that it gives to the countries near 
the line, exalts the colours of the (hells produced there, 
as it does the rich plumage of birds, and the more ele- 
• gant decorations of ferpents; and hence gives them a 
lultre and brilliancy that thofe of colder climates always 
want: and it may be, that the waters of thofe vail leas, 
which are not fubjeCt to be weakened by frefh rivers, give 
a nourifhment to the lift, that may add to the brilliancy 
of their (hells. 
Of the PARTS and CHARACTERS of SHELLS. 
In every fyllem of conchology, it is neceffary to fix 
fomeftandard or effential charaClers to all (hells, by which 
they may be divided into families or claffes, genera and 
fpecies. Thele characters mull always be formed from 
the chief parts of the (hells, the differences of which, in 
(hape, lize, fituation, or other marks or particularities, 
enable us to form rel'peftive families or claffes, and to re- 
folve thofe families into genera, and afterwards into fpe¬ 
cies, by other fubordinate charaClers. Thus in univalves 
there are five ltandard or effential charaClers for the claffes 
or families : thefe are, i. Simple or not turbinated. 2. 
Turbinated, with a fingle continued cavity. 3. Turbi¬ 
nated and chambered, or with many compartments or 
cavities. 4. The peculiar (liape. 5. The aperture, mouth, 
■or opening of the (hell. The fubordinate charaClers for 
genera and fpecies in univalves, are, 1. The number of 
(pires, convolutions, rounds, or wreaths. 2. Whether 
operculated, or covered with a lid, or not operculated. 
3. The (lielly fubllance, whether opake, horny, pearly, 
&c. 4. The epidermis. 5. The head, beak, or tip. As 
thefe charaClers include the principal parts of all uni¬ 
valves, they of courfe conftitute the rudiments of the fyf- 
tem; which rudiments ought to be wellinveftigated by every 
colleClor of (hells. It is laudable to colleCt; but when a 
colleCtor alio makes it his lludy to contemplate feientifi- 
cally the natural curiolities he acquires, he then claims 
the refpeCl of mankind, in addition to the praife already 
gained by his affiduity. 
The particular parts which enter into the conftruCtion 
of a (hell, are as follow : 1. The epidermis, or periolteum. 
This part is common to bivalves as well as univalves. It 
is a rough covering or (kin, which mod, but not all, (hells 
have ; and only on the outfide, never withinfide, the (hell. 
The epidermis, perhaps, is a periolte or membrane, that 
covers the (hells to defend them from exterior accidents, 
to preferve them, and aid their growth. In that it does 
the fame office as the periolte or membrane which covers 
the bones of other animals ; for the (hells of thele (idles 
may be considered, and indeed are, quite analogous to 
the hones of other animals. The epidermis feems as much 
a genuine covering of the (hell formed by the fifh, as the 
(hell itfelf. And, could we lee the recent fifh, and ex¬ 
amine its organs, there is no doubt but we (hould find 
Ygl. V. Ko. 250. 
TLOG Y. 17 
the rudiments of a proper apparatus for making the epi- 
dermis, as well as the (hell. The (IruCture of the epider¬ 
mises very different in different genera. In fo'me,it is 
laminated, in others fibrous and bruft-like. It dei'erves 
to be more minutely examined, and it feems not impro¬ 
bable but among the feveral ufes of this covering, the 
two following may delerve con federation : t. To prevent 
the fait water from corroding the (hell; for all (hells that have 
an epidermis have a fcabrous lurrace. 2. To prevent other 
fheli-fifh or marine infeCts from fixing their habitations 
on thefe (hells, as they do upon all bodies in the fea, 
where there is not a power of defence. And this renders 
it very probable, that all fillies inhabiting naturally fmooth 
(hells, are capable ot not only adding to the extent and 
growth of their (hells, but can likewife, from time to time, 
add a (reft poliflied covering to the whole (hell; at leaft 
their organs feeni to extend to fuch a length, as to clear 
away all impurities from their (hells. We leldom find any 
cowries with coral, or extraneous bodies adhering to any 
part of them. 
The head, (apex,) of an univalve, is the part juft over 
the mouth or aperture. The bafe, end, or tip, (bafm,feu 
acumen,) is that part of the other end oppolite to it, or 
the end of the turban; though fome authors have given 
them quite contrary names, by calling the tip or turban 
the part over the mouth. In (peaking of (hells it may be 
underflood, that when the upper or under lide, or ends, 
are mentioned, it is fuppofed that the (hell lies on its 
mouth upon a table, with the head towards the right 
hand, and the end or tip towards the left. 
1 he body of the (hell, (corpus,) is that part which runs 
from the top to the extreme limits of the aperture, and 
occupies the (pace between the bafe or turban, and the 
apex. A whirl, turn, fpire, or wreath, (fpira, anfraftus,) 
denotes each (ingle or (eparate turning or circumvolution- 
as in the turban of the whelk, or common (nail. The" 
difpofition of the (pires, fays Mr. Adanfon, is not the 
(ame iii all (hells; it varies according to the different 
plans they turn on, and they can turn on four different 
plans, which are; 1, the horizontal; 2, the cylindric, 
or fpreading on a cylinder; 3, the conic; and, 4, the’ 
ovoid plan. From thefe four difpofitions of the (hires 
all the different forms or figures of (hells proceed. Thele 
are the principal difpofitions of the fpires; but there are 
many intermediate ones, which proceed from different 
degrees and combinations of thefe four. The number 
and forms of the fpires vary in the fame fpecies, either in 
their different growths or (exes. Young (hells have al¬ 
ways a le(s number than the old ones; thereafon is, be- 
caufe all turbinated or fpiral (hells take their growth from 
the tip or end, to the mouth or upwards. Some (hells 
though of the lame age, fometimes have not the lame 
number of (pires: this is to be attributed to difeale; or 
perhaps, it may be an effe<ff of (ex. Thus, in the pur¬ 
puras, the buccina, and in fome other kinds, it is com¬ 
mon for the males to have their fpires lefs numerous 
more (lender and lengthened, or Id's (welled ; and the 
whole (hell (mailer than in the females. This obfe.rvation 
is always found to be conllant. 
Ehe tui ban, oi clavicle, ( cla c vicula,) is the ago*recr-ite: 
or whole let of the whirls, and always forms the lo%ver 
part of the (hell. A fiat tuiban, or helix, (clavicu/a helix ) 
is fo (lightly prominent, as to be nearly on a level with 
the bale of the (hell. There are likewife feveral other 
degiees of them, as the fliort turban, (ctcvvicilia. depre/Ta ■ ) 
the produced turban, (clavkuia longiore-,) the lorn i U r 
ban, (cla-vicula longiffvna;) all which are explained by 
the very names they bear. 
The pillar, (columella,) is the middle part, or axis 
which runs through the (hell, or from top to bottom, and 
from which all the fpires commence and turn round' and 
which forms the fupport or ba'fls of them. It aiwa\ s lies 
afide the mouth, and though not (een in all the (lulls yet 
in many it is the mod obvious part of the mouth next the 
lip. The mouth or aperture, (aperlura,) needs no ex- 
F plaiiation. 
