S30 
ENTOMOLOGY. 
organization of the eyes of infers. Among other things, 
he has (hewn, that under each facet there is a pyramid of 
fibres broad at the bafe, and growing fmaller as it pro¬ 
ceeds inwards ; the pyramid has the fame number of Tides 
as the eye, and there are as many hexagonal pyramids, 
as there are fmall facets or eyes in the infedl. An innu¬ 
merable number of pulmonary tubes afcend thefe fibres, 
terminating in a white fibrous convex membrane ; under 
thefe membranes there is another, fiill more delicate and 
tranfparent; beneath this,, a fecond fpecies of fibres is 
tranfverfely applied, like To many beams to fupport the 
pyramids that are laid upon them. Still we cannot deter¬ 
mine with certainty, how thefe numerous inlets to fight 
operate for the fervice of the animal; they may increafe 
the field of view, augment the intenfity of light, and be 
productive of advantages of which we can have no con¬ 
ception. Hooke computed 14,000 of thefe facets in the 
two eyes of a drone ; Leeuwenhoek reckoned 6036 in the 
two eyes of a filkworm, when in its fly ftate ; in the eyes 
of the libellula lie reckoned 12,344 hexangular lenfes. 
Swammerdam covered the reticulated eyes of certain in¬ 
fects with black paint; in this ftate they flew at random, 
and feemed to be deprived of their ftrength ; when they 
fettled, they did not avoid the hand that was going to 
take hold of them. Reaumur made fimilar experiments 
on the eyes of bees, which concurred with thofe of 
Swammerdam. 
Some ephemera flies have four reticulated eyes, two of 
which are placed as in the common fly; the other two 
are placed, one befide the other, upon the upper part of 
the head, and have the appearance of a kind of niufti- 
room, the head extended fomewhat beyond the ftalk. 
The firft pair are of a brown colour, thofe of the mufti- 
room form are of a very beautiful citron colour. In many 
of the fly clafs, thefe reticulated eyes are little inferior 
in colour and brilliance to the brighteft gem. The colour 
varies in different fpecies; in fome we find it green, in 
others red, &c. fome have a mod elegant changeable co¬ 
lour thrown over them, partly purple, partly green, and 
partly of that braffy hue which is feen on the backs of 
fome of the beetles, and which is not equalled by any 
other produdlion of art or nature. 
It might be imagined, that as every fly has two reticu¬ 
lated eyes, they could not have occafton for more ; but 
fo it has not appeared to that Great Being who formed 
them, for many are furnilhed befides with other eyes, 
differing in form and conftrudfion from thofe that are re¬ 
ticulated. Thefe were firft noticed by M. de la Hire ; 
they are three lucid protuberances placed on the back 
part of the head of many infefts; their furface is gloffy, 
of an hemifpheric figure, and a coal-black colour. They 
are tranfparent, and difpofed in a triangular form ; by 
modern entomologifts they are termed Jfenvnata. Reaumur 
made experiments upon thefe eyes, fimilar to thofe he 
had made on the reticulated ones, and found that when 
the (lemmata were covered with dark varnifh, the infefts 
flew but to a fmall diftance, and always at random. No 
infeft feems to poftefs both kind of eyes, unlefs in its 
perfect ftate: there are many fpecies which are not ftir- 
niftied with (lemmata, gnats and tipulm are without them. 
But the mod extraordinary conftrublion of the eye per¬ 
haps in the whole tribe of infects, is that of the diopfts, or 
fpedtacle-fly. In this infebt the eyes are placed on the 
extremity of two long, (olid, inarticulate, filiform horns; 
the extremities of which form a kind of focket to receive 
the eyes, which are fpherical, and lucid black. See the ar¬ 
ticle Diopsis, and the engraving of the fly, vol. v. p. 842. 
Body. —The trunk or body of the infect is fitnated 
between the head and abdomen. Entomologifts divide 
it into three parts : the thorax, fcutellum-, and fternum. 
The thorax is the part of the body next the head, and is 
of various fliapes and proportions ; the Tides and back of 
it are often armed with points. The fcutellum, or efeut- 
cheon, covers the part between the thorax and abdomen, 
and is generally of a triangular form though it adheres 
to the thorax, it is eafily diftinguiflied from it by its 
figure, and often by an intervening future. It feems in¬ 
tended to aflift in expanding the wings. The Jiernum is 
fituated on the under part of the thorax ; in fome fpecies 
it is pointed behind, as in the elateres; in others, bifid, 
as in fome of the dytifei. In (hort, the thorax is the fto- 
mach of infefts; and is either round, triangular, cylin¬ 
drical, thick, (lender, &c. It may be confidered as com- 
pofed of fix faces, like a cube, which form it fometimes 
affumes, and is often terminated by a kind of border, and 
then called viarginated. 
Abdomen. —The abdomen contains the inteftines, air- 
veffels, &c. It is compofed of feveral corneous rings or 
fegments, fo that it may be moved in various directions, 
or lengthened and fhortened at pleafure ; in fome it is 
formed of one piece only. It is perforated with fpiraculi, 
or breathing holes, and is terminated by the tail. The 
Jpiraculi are fmall oblong holes or pores placed fingly one 
on each fide of every ring or fegment; thefe are the 
means or inftruments of refpiration, which fupply the 
want of lungs, and form a peculiar charaCteriftic of in- 
fefts. The organs of generation are placed in the extre-- 
mity of the abdomen. 
Limbs.— By the limbs are meant the inftruments ufed 
by the infeCt both for motion and defence. They are, 
ala, the wings; halteres, the poifers; pedes, the legs; 
cauda, the tail ; and aculeus, the (ling. 
The wings are thofe inftruments by which the in fed is 
enabled to fly; fome have only two, others are furnilhed 
with four, two on each fide ; thefe are, in fome, of the 
fame (ize ; in others, the fuperior ones are much larger 
than the inferior: Linnaeus has made them the founda¬ 
tion of the feven orders into which he has divided this 
numerous clafs of beings. The variety in the form and 
ftruClure of the wings is almoft infinite; the beauty of 
their colouring, the art with which they are connected to 
the body, the delicate manner in which fome are folded 
up, the fine articulations provided for this purpofe, by 
which they are laid in their cafes when out of ufe, and 
yet ready to be extended in a moment for flight, afford 
an inexhauftible fund of curious inveftigation. The wings 
of moths and butterflies are moftly farinaceous, covered 
with a fine duft, which, by the affiftance of the microfcope, 
appears to be a regular affemblage of organized fcales. 
The following terms are applied to the different kinds 
of wings. They are firft diftinguifhed, with refpeCt to 
their furfaces, into fuperior and inferior. The part next 
the head is called the anterior part; that nearer the tail, 
the pofteiior part. The interior part is that next the 
abdomen; the exterior part is the outermoft edge. Thofe 
wings are termed plicate, which are folded when the infeCfe 
is at reft, as in the wafp. Plane, when incapable of being 
folded. EreEl, when the fuperior furfaces are brought ini 
contadl when the infedt is at reft, as in the ephemera,' 
papiliones, &c. Patent, if extended horizontally when 
the infeft is at red, as in the phaheme geometrae. ham n 
bent, if when they are not in motion, they cover horizon¬ 
tally the fuperior part of the abdomen. Dejlexed, are alfo 
incumbent, but not horizontally, when the outer edges 
decline towards the (ides. ReverJ'e, are alfo defiexed, with 
this addition, that the edges of the inferior wings projefe 
from under the anterior part of the fuperior ones. Dentate, 
when with ferrate or feolloped edges. Caudate, when the 
fibres of the wings are extended beyond the margin into 
a kind of tail. Reticulate, when the veins or membranes 
of the wings put on the appearance of net-work. 
The wings are further diftinguiflied by their ornaments : 
when painted with fpots, macula-, bc\t\Ai,fafcia -, (freaks, 
Jtriga: when thefe are extended lengthways, they are 
called lines, lina ; and if with dots ,'punCla-, one or more 
rings; or fpots are termed eyes, ocelli-, if the fpots are 
fhaped like a kidney, they are termed Jligmata. Thefe 
fpots or eyes are mod common to the wings of the 
butterfly. 
The elytra, or cruftaceous (hells or cafes of the wings, 
x are 
