CONCH 
s 
fhoit, and he balances himfelf and extends them as he 
fwims. The two hinder ones, longer than the others, lie 
plunges in the fea, to ferve as a rudder; and thel'e up¬ 
hold the (kin, or membrane, which he ufes for a fail to 
catch the wind. Thus equipped, he navigates in calm 
weather ; when fearful of danger, he retires within the 
(hell, by which aftion it gains water, and finks. He of¬ 
ten pumps the w’ater out, and alfo quits the (hell, which, 
floating empty, is carried by the waves, and either thrown 
on-fhore, or dallied to pieces on the rocks. 
The (i(h can quit the (hell at pleafure, for he appears 
not to be attached to it by any part of its body. Fre¬ 
quently he turns himfelf and (hell topfy-turvy, and rifes 
with his head downwards from the bottom of the fea ; 
and, when he has gained the furface of the water, he 
turns his (hell very nimbly, empties the water, extends 
his arms, and lets fail. They are frequently taken with¬ 
out their (hells; and the fifhermen mult be extremely ex¬ 
pert to catch them in it. This account, however, feenis 
fomewhat doubtful, becaufe we know not of any animals 
that have proper domicilia, who quit them voluntarily. 
Fear or neceflity may po(Tibly caufe this feparation fome- 
times. Befides, as this animal may be fuppofed to frame 
its own habitation, like others of the teftaceous kind, it 
feems neceffary to hive an attachment, however (light, to 
tome one point, as that from which it uniformly extends 
itfelf for the formation of its (hell: if this were not the 
cafe, is it poflible to conceive, that a (hell fo delicate, fo 
regular in every refpedl, could be fabricated ? Knorr en¬ 
deavours to account for this phenomenon, by fuppofing 
that the tentacula or arms of thel'e animals, and even 
their fibres, a£t as fuckers, and that they thus keep them- 
i'elves attached to their (hell. For it is well known, that 
in this manner, if two fmooth adhefive bodies touch one 
another in many places, they make a cohefion nearly as 
Itrong as though they w r ere united together: and who 
can decide whether the inhabitant of this (hell does not 
flick by fibres infinitely fmall in the cavities of the 
ierratures which are found on the keel ? and whether thefe 
fibres do not confill of a vilcous liquor, which presently 
diffolves; and for that reafon cannot fo readily be ob- 
ierved ? The uncertainty, however, of the mode of con- 
ta6l between this animal and its (hell, has rendered the 
manner in which it conllrudls its abode very queftiona- 
ble; for there are Come naturalifts who fcarcely conceive, 
by the formation of the (hell, that a cohefion of any part 
of the animal’s body therewith can be at all neceffary ; 
for in that cafe, fay they, it would contrail the growth of 
that part of the (hell which adheres to the animal: yet they 
cannot explain how the part which is free from the (hell 
can increase itfelf, though there are fimilar precedes ob- 
ferved in nature. As when, for indance, a (ilk-worm, is 
changed into the cryfalis or aurelia, it condruits its (hell 
from its external (kin; and taking the form of a butter¬ 
fly, it keeps itfelf during the lad peri.od in this (hell, with¬ 
out being attached, and afterwards freely comes out at 
its own pleafure. Now, might not the paper nautilus 
condrudl alfo a covering round its body from its own 
vilcous moidure, which, afterwards growing hard, would 
come od' from the animal entirely, and leave him a free 
habitation ? This might really be the cafe, though it is 
offered as a mere lugged ion. The animal being now dil- 
engaged, the (hell becomes thicker by the vifeous matter, 
which runs through the pores of the animal, or which it 
receives from the orifice of the new additions or folds, as 
the fize of the fifh increafes. There is no foundation to 
fuppofe that the polype, fometimes taken in this (hell, is 
its natural inhabitant. And although we all agree that 
this creature is fattened lefs firmly to its died than other 
teftaceous animals, yet we cannot but fuppofe that it is 
united, and has contail by fume effeflual means, though 
as yet undifeovered, and unafeertained by man. How 
eife are we to explain the increafe of its elevated fides; 
the growth of the blunt teeth fymmetricaily ranged ; and 
theorganicalftruFture difeovered by Mr. Herifiant,without 
Vol, V. No. 251. 
O L O G Y. 35 
a fuppofition of there being a (yftem of veins or arteries 
within the diell, efpecially fince the animal has a form fy 
totally different from that of its abode ? 
For a correct view of this (hell, which is the argonautn 
argo of Linnaeus, fee the Conchology-Plate V. 
AURIS COCHLEA, on EAR-SHAPED SNAIL- 
SHELLS. 
The eighth family is formed of the ear fnails, or auris- 
cochlea, a combination of two names, which expreffes 
the affinity thele drells have to the fea ears, while, at the 
fame time, they are truly a kind of cochlea or fnails. To 
this clafs belongs the Venus ear. Their (hape fo much re- 
fembles the fea ears, that mod authors have ranked them 
in that family, and call them noil-perforated lea ears. 
Lifter and Gualtieri rank them as cochlea;, and Linnaeus 
places them in his genus helix. Da ‘Cofta defines the 
auris-cochleas as follows : (hells fo wide and open as to re¬ 
ferable fea ears, but are not perforated or fet with a row of 
holes. They have a broad ledge along one fide, which 
projects over the cavity, and turbinates into one (ingle 
flat fpire, quite even or level with the bottom of the (hell. 
This fpire is alfo very wide ; and extends to near the 
middie of the bottom or under part: fo that this family 
abfolutely participates of the charaflers and (hapes of 
the fea ears, and of the fnails, and is, as it were, a com¬ 
bination of thofetwo families, as alto one of the innume¬ 
rable inflances of the inlenfible pregrefliona nature takes 
from one family to another ; which progreffions baffle hu¬ 
man abilities to limit, or the refined definitions of tiie 
mod accurate naturalifts. Though there are great num¬ 
bers of thefe (hells, yet there'are not many different (pe¬ 
des of them. They are figured in the engraving as the' 
next in order to the argonaut, or paper nautilus. 
The CYLINDRI, or OLIVES. 
Thefe (hells are a fpecies of voiuta, and conftitute Da 
Coda’s ninth family. They are of a cylindric form, and 
pointed at the lower end; the mouth is long, narrow, and 
notched on the top; the notch turning backwards, is 
large and fomewhat awry, like the mouth of a flat fifh; 
the pillar is faced half way down, and is greatly wrinkled 
or plaited ; the turban is generally fhort, very pointed, 
with the whirls or fpires nearly level, or merely promi¬ 
nent one from the other; and the turban itfelf is divided 
from the body by only a mere prominent line. 
This family, in moll authors, is claffed nearly in the 
fame manner. Lifter calls them, rhombi five ftrombi cy- 
lindracei. Rumphius forms a genus of them which he 
calls cylindri. Argenville makes them his eleventh fa¬ 
mily, and names them rhombus, cylindrus, or olea. Da¬ 
vila places them as two genera of volutes, viz. as the fe- 
cond genus or cylindrical volutes or rouleaux, and as the 
third genus or dentated volutes or olives : and Meufchen, 
whofe leventeenth genus they are, alfo calls them cylin¬ 
dri five dailili. Gualtieri names them cochleie cylindroi- 
deas, and places them the next genus after the volutes; 
and Linnaeus ranks them in his genus of voiuta, by the 
name of cylindroideie. 
This family admits of being divided into two genera, 
viz. 1. Cylindri emarginati, or (itch whole edge is quite 
even and (harp. And, 2. Cylindri marginati,- or (itch 
whofe edge is not (harp and fmooth, but has a very thick 
border, which turns over into a very prominent ledge on 
the back like the helmets. The (pecies of this family 
are numerous, and are very beautiful (hells. Specimens 
of them are given in the copper-plate. 
The VOLUTES and CONES. 
The tenth family of this divifion.of univalves is-the 
volutes and cones. It is very numerous in its fpecies, 
and is the family which, for richnels and beauty of co¬ 
louring,. l’uvpaffes alm<?it all the other univalves, ami js 
reckoned the great ornament or capital obje£l of collec¬ 
tions. The far greater number of cones always bear a 
H value; 
