4.6 
againft any thing. Thus the eye is defended 
and kept fafe. Moreover, thefe extreme ends 
of the horns are ftretched f{mooth, and have a 
bright furface, fomewhat red, and full of pro- 
minences or little warts; but the glands eee ap» 
pear to be fituated a little lower, between the 
globular production of the horn, and they are 
likewife divided on the infide by very {mall 
whitith points. The furrows or ridges vifible 
at the bottom between thefe glands, are the 
veflels which carry the glutinous humour to all 
thefe parts, and again bring it back from them. 
And that thefe mufcles and nerves may lie con- 
venient, the whole horn is hollow f on the 
infide; fo that if it be diffected tranfverfely, the 
extremities of thefe parts prefent themfelves on 
the infide. | 
To have a more clear idea of this matter, it is 
neceflary to open the Snail, for which purpofe 
you muft have a fmall and tharp-pointed pair 
of fciflors; one of the points of thefe fhould 
have a little ball made of fealing wax fixed on 
it, to prevent the inward parts from being 
wounded. Then, after opening the middle of 
the back, the body muft be cut to the verge of 
the Snail, Tab. IV. fig. 1. e; after this direct 
the {ciffors forward, and diffect the skin as far 
as the fore part of the head, between the two 
upper horns. The diffection being thus made, 
the firft thing to be met with, immediately 
under the skin, isa certain mufcular delicate 
membrane, which is very thin and fine, it 
covers all the inward parts, and is provided, 
here and there, with mufcular fibres, which 
run acrofs from one fide of the body to the 
other, and are inferted into the fides of the 
fhell; you may alfo then fee the ftomach, or- 
gans of generation, and the like. Afterwards 
the brain, which lies on the upper part of the 
ftomach and over the gullet, prefents itfelf; 
and immediately afterwards, the horns them- 
felves drawn back, with their mufcles in the 
abdomen. 
Having thus briefly touched upon thefe mat- 
ters, I {hall proceed to explain and defcribe by 
ficures, how thefe four horns, Tab. IV. fig. vi. 
I, 2, 3, 4, are circumftanced, when they are 
drawn into the body, and their inward fides are 
turned out; for which purpofe, each of the horns 
has its proper muscle. The two upper and largeft 
horns have their particular mufcles aa, each of 
which is connected by its proper tendon to the 
two mufcles which move the middle of the body, 
and thefe are afterwards with them inferted by 
their tendons into the fpiral part or folding of 
the thell, Tab. VI. fig. 11. 44, un, a. 
The two lower horns, not being of fuch im- 
portance as the upper ones, are provided with 
two {maller mufcles 44, which arife from the 
larger cc, and draw in the lips of the fnail. 
This is likewife reprefented in Tab. VI. fig. 11. 
ll, mm. , 
The manner in which the horns are twined 
and ftretched out of the body, isa much more 
difficult thing to be defcribed ; though I think, 
indeed, that the inward coat, or mufcular part 
The B-O°O7K of NM AYP OU Rae: oF, 
of the horn, performs that office, with thé 
afliftance of fome other {maller and adjacent 
mufcles, as well as fome ftronger ones, whereby 
the fore part of the head, and the skin of the 
{nail is moved towards the outfide. The true 
action, which I think the inward annular 
mufcles have, feems to confift in this, that 
fome of them are fuccellively contracted and 
ftiffened after others, by which means the horn 
is continually rolling out, and one {mall portion 
of it is pufhed after the other ; to this action, 
the periftaltick motion of the inteftines, as far ~ 
as the latter is performed by the contra¢tion of 
the annular mafcles, bears fome, though per- 
haps a diftant, refemblance. 
But the optic nerves deferve more confidera- 
tion; both on account of their texture and their 
motion. Before I defcribe thefe, I fhall take 
occafion to fay fomething of the brain, from 
which they arife. The brain d confifts of two 
globular little parts; and, by this property, is 
divided into two portions, as it is in man. 
The firft is placed in the head; but becaufe 
this; as well as al! the other parts of the fnail, 
is, in a wonderful manner, moved fometimes 
backward and fometimes forward, no fixed 
or certain place can be affigned to it. I there- 
fore fhew both the brain and optic nerves im 
the fituation wherein I have delineated them. 
The hinder part of the brain, is drawn in 
Tab, IV. fig. vi. e, to the skin of the fnail’s head, 
and is fituated a little above its fhining tooth /; 
for the brain, together with all the parts of the 
gullet and mouth gy, and alfo the {tomach and 
falival veffels 77 are driven to this depth into the 
body, by the ftrength of a mufcle appointed 
for that purpofe; but when all the parts are 
again rolled or turned out, we may then fay, 
the brain is placed at the fore part of the head. 
Hence it is evident, that the motion of the 
brain in this creature ought to be obferved as a 
thing worthy of the higheft admiration ; 
wherein both the wifdom and infinite power 
of the almighty are manifeft: fince he has 
been pieafed to render this part, which in 
man and other animals he made immoveable, 
by enclofing it in a hard bone, capable of mo- 
tion inthe {nail, by the power of its mufcles. 
The optic nerves of the firft pair of horns 
having fpiral originations £4, arife on both fides 
from the brain, which has been fo contrived 
by the omnipotent wifdom of God, that they 
might conveniently obey, and evolve or turn 
themfelves out, when the horn is, in fo ftupen- 
dous a manner, protruded forth out of the body; 
and to prevent the leaft diforder from this 
egrefs and regrefs, the omnifcient creator of the 
univerfe hath involved and fortified thefe 
nerves with ductile membranes // and ligaments, 
with fo much art, that no fuch diforder is ever 
to be feared. Nay, left this nerve fhould be in 
any danger, when it is turned up and down 
inwardly in the cavity of the moveable horn, 
the wifeft of all architeéts has conftructed 
that part of the mufcle which is fixed to the 
extremity of the horn in fuch a manner, that 
at 
