Th HiSDORY VP INSHGITS 61 
vefiels are extended'near the cartilages. More- 
over the beginnings of the appendages are feen 
very beautifully in the thorax, as has been be- 
fore obferved. 
After thefe little parts, together with the 
ftomach, heart and inteftines are removed, the 
{pinal marrow prefents itfelf to view: it is 
placed entirely at the bottom of the thorax, 
and is not inclofed in a bone. It extends it- 
{elf through the lower parts of the abdomen 
to the tail of the creature; and there terminates 
inthe mufcles of that part. In order to de- 
{cribe this matter the more exactly, it muft be 
obferved, that the brain, Tab. XI. fig. 1x. aa, 
from which this marrow arifes, is fituated 
immediately under the articulations of the eyes 
in the head, which is very fhort, and joined to 
the thorax. This brain is feen to be there 
divided into a right and left part. Above the 
brain appear the optic nerves 64, which are 
found to decuffate over it, and to proceed to-= 
wards the eyes, as I fhall now fhew. Under- 
neath, out of the bafis of the brain, arife two 
{trong nerves c, which properly conftitute the 
origin of the marrow in the thorax: thefe 
nerves are placed at.a confiderable diftance 
from each other, in order to give a paflage to 
the gullet, which is very fhort, and reaches 
from the mouth to the ftomach. The brain is 
therefore placed over the gullet, and the gullet 
again, as well as the ftomach and inteftine, 
are lodged upon the marrow in the thorax and 
abdomen. ‘Thefe two originations of the 
marrow are again united a little below, and 
there form a remarkable {welling or knot d, 
out of which many nerves iffue, which are 
diftributed over the mufcular parts of the 
thorax as well as the brachia and legs. In 
men and quadrupeds fuch clufters are never 
feen in the body of the marrow, but always 
in the nerves after they have iffued out of that 
part; but this is indeed the fame thing in 
effect, for as the marrow itfelf is as it were a 
bundle of nerves, and is double in all fpecies 
of animals, it is the fame thing whether thefe 
clufters are found in the marrow, which is a 
kind of thick and compound nerve, or in the 
‘nerves iffuing from thence, which are the {e- 
parate portions of the marrow. Whoever accu- 
rately confiders the matrow in man and other 
animals, will indeed moft clearly obferve this 
analogy; though Malpighius himfelf does not 
feem to have obferved it, when he fuppofed 
there was fo great a quantity of brains in the 
marrow of filk worms. After the marrow 
has formed this clufter in the Hermit, it 
becomes fimple again, though its two parts 
may, notwithftanding, be palpably diftinguifh- 
ed; but thefe are fo nearly applied and conti- 
guous to each other, that they are as if they 
were but one. Afterwards is difcovered ano- 
ther clufter of marrow, and a third, fourth, 
fifth, nay, a fixth, ee ee e; the nerves of this laft 
are detached to the mufcles of the tail. ‘The 
nerves which arife out of thefe little clufters, 
are almoft all beftowed on the mufcles of the 
abdomen; whereds on the contrary, thofe 
that iffue from, the marrow itfelf, Tab. XI. fig: 
ix. ff, are likewife diftributed to the vifcera. 
It is likewife worthy of notice after what man- 
ner the nerves decuflate one over another, which 
I demonftrate in thofe nerves which iffue be= 
fore the laft clufter out of the marrow g, and 
are detached to thé mufcles of the abdomen. 
After the optic nerves have iffued from thé 
brain, they are inclofed in the annular 4 cruft 
of the eye; and being again confiderably ex- 
panded in the latter, they thus proceed to the 
verge of the cornea tunica, and there termi- 
nate like {pheres, or in globular forms. No hu- 
mours appear any. where in the whole eye, 
like thofe found in the eyes of mesj quadru- 
pedes, birds, and terreftrial or water Snails ; 
but it is obferved to be of a texture entirely 
different, which is very worthy of attention. 
If the cornea z be taken from the eye, there 
is immediately feen under it a kind of limpid 
matter, fig.x. &, which is the colour of jelly, and 
is divided in a very elegant and regular manner, 
What part this is, and whether it has its ofi- 
gin from fpirit of wine, I cannot exactly de- 
termine, as I never faw any thing like it in 
any infects, whofe eyes are of the fame ftruc- 
ture. I {hall therefore at a proper time exa- 
mine this little body, in the larger Crabs 
diffected alive. 
But before I proceed further, it is to be 
known, that the cornea tunica is divided like 
a net, in the fame manner as in the eyes of 
infects, but thefe reticulated divifions are here 
much deeper. I find every divifion to be 
hexagonal, as well in this Hermit as in infe@s, 
Moreover, all thefe divifions wind themfelves 
above in a fpherical gure, which however is 
not here very remarkable, fince the ariole or 
little beds of the divifions, are very {mall and 
fmooth. On the infide, in the hexagonal cavi- 
ties of the divifions of the cornea, was fixed 
the glutinous matter before deferibed, which 
was there divided in the fame manner as the 
cornea itfelf, Under the latter appeared a 
great number of little fibres, fig. rx. /, which 
are placed on the internal furface of the eye, 
in the fame manner as the feeds of the plant 
turnfol are fixed in their cups. All thefe fibres, 
which fupport the glutinous matter aforefaid, 
are connected together by the help of a mem- 
brane of a black colour on the infide, but 
above of a tranfparent green on account of the 
matter; I therefore call it the uvea tunica. 
The ftructure and fituation of thefe formed 
as it were an inverted pyramid, with its {mall 
point turned downwards; but when I fepara- 
ted thefe little fibres from each other, they ap- 
peared above as black as pitch, Tab. XI. fig. 
x. m, but below only of an obfeure or dark 
brown x, and pellucid in the middle o: all of 
them terminated at length in a gray fubftance, 
and under this the extremity of the optic 
nerve came in fight. 
When I viewed thefe fibres with a microt- 
cope, I found each of them confifting of 
other 
