brane is another, which is more delicate and more tranfparent;.
but connefted with it by means o f pulmonary tubes ; under this
there is placed a feeond fpecies o f fibres, tranfverfely applied, like-
fo many beams, to fupport the pyramidal fibres that are laid,
over them.
Each fide o f the head o f a fly, which is cut as it were into a
multitude of fmall' facets, is one o f the reticulated eyes o f the
creature. Nature allots two o f thefe reticulated eyes to each fly ;
and as they each contain fuch a valt multitude of finaller, but
perfeft eyes, one would imagine them to be very fuffieient for all
the oecafions of the animal. There are, however, certain flies o f
the ephemera kind which have four o f thefe reticulated eyes, two
o f which are placed as is ufual in the mufca, and are but of fmall.
extent ■ the other two have each thé appearance of a fort o f turban,
and are placed one befide the other upon the upper part of:
the head.
Thefe have fomewhat the figure of a mufhroom, the head o f
it extended a little beyond the {talk, and the upper convex Surface
cut into almofl an innumerable quantity o f facets..
The firft pair of the reticular eyes o f this fly, which are placed,
as thofe of the other flies, are in colour brown; thofe o f the
mufhroom form are of a very beautiful citron-colour, and as
tranfparent as the mofl pellucid reticular eyes of other flies ; for,
among the various fpecies, fome have thefe eyes much more
tranfparent than others. The fly, thus remarkably furnifhed
with eyes, is produced from a worm of the fame kind with the
common fpecies ©f ephemerons; it’s body is o f a pale yellow,
and-.
-and it’s wings white; the two inferior ones o f thefe are lo final!,
that they are not eafily diftinguifhed.
Among the fly clafs thefe reticular eyes are, in different fpecies,
of different colours ; there are fome which have them brown,
-others yellow, others green, and -others red, and this in all the
different fhades of thofe colours. Some of them have alfo the
glofs of metals highly polifhed, others afford us a view o f changeable
colours, and others have arrangements of different colours,
fixed and invariable. The eyes of one fpecies of the gad-fly, fo
troublefome to oxen, have ftreaks o f red, green, and brown,
placed alternately.
One would imagine, that as every fly has two o f thefe reticular
-eyes, each compofed of fuch a multitude of real eyes, they could
have no ©ccafion for any more ; but fo it has not appeared to the
great Being that formed them, for many fpecies are furnifhed
with more eyes, which differ both in conflruftion and form from
thofe that are reticulated.
The eyes already defcribed are properly called reticular ones';
and to avoid confufion, it will be neceffary to defcribe thofe
which differ from them by fome determinate name (they are now
generally termed the {lemmata}; thefe, when examined by the
belt microfcopes, appear of a perfeftly finooth, gloffy, and
polifhed furface, but plain and Ample, without the leaf! appearance
o f a reticulated texture. They are alfo much finaller than
the reticulated eyes, and may therefore be called, by way o f
diftin&ion, the finaller finooth eyes, or the flemmata.
Z z 2 M. De