ete ior JOR YN of ft Neh Ee. GT S. 
together with the palate, and fome other parts 
annexed. I defcribe and reprefent this in fuch 
a manner, that the bafis of the tongue g, and 
its fore-pointed extremity f, which is armed 
with a kind of horney teeth, may be clearly 
diftinguithed ; although they are all neceflarily 
put fomewhat out of their natural fituation. 
Afterwards appear thofe two admirable muf- 
cles 45, which, by turning in the two upper 
horns through their cavity, draw the eyes back 
into the body; the curled foldings 27 of the optic 
nerves are found to be tranfparent through thofe 
mufcles, and are feen to run towards the eyes. 
The eyes themfelves feem like two black 
points &&, over which a certain part of the horns 
thus drawn in {till appears: under the former, 
are feen two plain, equal, or fmooth mutcles /, 
which draw the lips and fome other parts of 
the mouth into the cavity of the body; at the 
fides of thefe appear a pair of mufcles mm, 
which are inferted in thofe of the lips before- 
mentioned, and ferve to draw back the two 
‘lower horns into the cavity of the Snail’s 
neck. Between the mufcles hitherto defcribed, 
are found two very wonderful and ftrong muf- 
cles 27, which are inferted with two firm and 
tough tendons in the middle of the body ; this 
is varioufly and ftrongly moved by them, and 
is raifed or elevated into the orifice of the thell 
by their power ; between the tendons of thofe 
mufclesis the proper place of the {pinal mar- 
row in the Snail, which from thence diftri- 
butes its nerves to all the adjacent parts; the 
latter fupplying the nervous fluid or moifture, 
and giving the power of moving and contra¢t- 
ing ; as may be feen very diftinétly in the body 
itfelf. But after what manner the bone of the 
little habitation or fhell of the Snail is formed, 
and what windings, partitions, cells, divifions, 
and cavities it has; this truly fingular piece of 
art may be traced very eafily in a natural thell, 
as I have endeavoured to exprefs its ftructure, 
according to nature, with all the accuracy of 
which I was capable. Laftly, the extreme edge 
of the fringe or foot of the Snail, Tab. IV. 
fig. 11. 9999q, in which I have delineated all the 
mufcles hitherto mentioned, deferves to be 
carefully regarded. The flefh, and the fibres 
and tendons are of a fpotlefs white, fo that 
there is not much difference in this refpect 
between the flefhy and the tendinous part, 
unlefs for the fmallnefs and folidity of the 
fibres. 
Thofe parts being, in the firft place, thus 
explained and underftood, I fhall proceed to 
defcribe and to expofe to fight the inward 
parts of the fhell. The firft part which deferves 
confideration, is the outward orifice of the 
fhell, fig. 111.4; which being by little and little 
contracted and twined round, forms its fecond 
divifion 4, and thence afterwards afcending 
further, it forms a third ¢, and at length a 
fourth d, and a fifthe, which is the laft, and has 
the extreme end of the liver placed in its 
cavity. 
63 
If any one diffects the fhell with a fine faw, 
made of a {mall piece of a watch fpring, and 
afterwards breaks open all the inward cells and 
divifions with a fharp pointed forceps, he will | 
fee very beautifully how this turning about or 
winding on the infide is effected ; and how the 
five feparate lodgements in the thell are com- 
pofed and twifted ina fpiral form, as I have 
reprefented from the life, in Tab. VI. fig. rv. 
numbers 1, 2, 3, 4,and 5, ‘hha 
The fhell of the Snail makes as beautiful a 
figure, if it be prepared in the following man- 
ner; it isto be cut fo that the inward poft, or 
the columella or pillar, about which all the cells 
and inward divifions are turned, remains alone ; 
in this cafe, in the upper end of the pillar, 
where the fifth and laft lodgement is opened, 
there is feen a fmall aperture, fig. v. 2, which 
paffes 6 through the whole pillar, from top to 
bottom, and is always larger and wider at the 
entrance of the fhell, than where the decreafing 
windings are terminated. Thefe apertures are 
feen yet plainer, if the loweft part of the pillar 
be taken off, fig. vi. c, and the pillar itfelf con- 
fidered apart. In many kinds of thefe bony 
habitations, thefe apertures of the pillar are 
very plain, from this caufe, that all the wind- 
ings of the fhell have each their particular and 
diftinét divifions, which are faftened and joined 
together in their twiftings: we are to except 
from this account, fuch fhells as have no wind- 
ing, and are therefore called tubules or tubular 
thells, 
For thefe reafons, therefore, this kind of 
fhelly covering muft be conceived as a certain 
oblong, hollow, fharp, and flexible tube, which 
if rolled and turned round a {mall iron line or 
wire, and afterwards this thread or line were 
drawn away from it, would thew fuch a per= 
forated pillar, which would be the more exaé, 
if all thofe foldings, together with their inclo- 
fures, were applied clofely to each other, and 
faftened and united together. And after this 
manner are almoft all kinds of {uch little thelly 
habitations built, in whatever wonderful manner 
they appear to be turned or conftru@ed. This I 
myfelf have found, by ftri@ly examining many 
different kinds of them which are jn my 
father’s mufeum. This appears however much 
clearer in fome fpecies than in others, in thofe 
fhells, particularly, which are called tubules, 
and which are twifted, Tab. VII. fig. v.4, only 
at their extremity. This conftru@ion is fo plain 
as to be beyond all manner of doubt. I fhall 
therefore hereafter exhibit other kinds of thells 
in their proper places, that the difference may 
he known as far as poifible, and by the fewett 
examples. 
From each of thefe larger habitations may 
be formed as many fmaller as can be defired, 
provided we firft break off the pillar and the 
internal ridges, and afterwards make them 
even and {mooth with a file. This is indeed con- 
trary to the order of nature, for the always 
proceeds from the lefs, Tab. VI. fie. vir. d, to 
the 
