213d NATURAL HISTORY. 
wings, there are the Papillionaceous, whofe lower wings are very trati¢ 
fparent, while the upper are a little opaque, which is obfervable in thé 
Flies of feveral water Moths. Other Flies have opaque fpots on theif 
fore wings, on a very tranfparent ground, thefe may be feen in Scot 
pion Flies. ‘There are alfo [lies with two wings, with dark fpots there* | 
on, feparated by tranfparent fpaces. 
The feelers likewife ferve to diltinguifh the feveral kinds of Flie$ 
from each other. For there is as much difference among the feelers 0 
Flies, as thofe uf Butterflies. In fome fort of Flies the feelers are jointed, — 
and as it were compofed of feveral grains, placed upon each other liké 
beads. Thefe are generally thicker at the roots than at the extremi- 
ties. Other Flies have their feelers compofed of joints like the for- 
“mer, but then they grow thicker towards the extremities, and thefe aré 
called clavated feelers, that is, they are like clubs. The Flie of thé 
Formico. Leo has this fort of feelers. Several {mall forts of Flies, as 
Gnats, and fome of the Vipule, have feelers like feathers, and other$ 
again in the fhape of prifms; but thefe are jointed, and more flendef 
at theit ends than at the middle. Some Flies have branched or forke 
feelers, being compofed of two articulated parts, and fo éach of then 
feem to be double; but thefe are only found in fome fort of Butterflies. 
Others have their feelers very fhort, but extremely thick, and confi 
of only two or three joints, and thefe are met with in many forts © 
Flies with four wings. Likewife the carriage of the feelers may fervé 
for another diftinGion ; as for inflance, the Ichneumon Flie keep the 
feelers in contmual agitation. 
Flies may alfo be diftinguifhed by their trunks, for fome have them 
fimple, and others armed with teeth or nippers. Some again have 4 
heath compoied of a fingle piece, while others confit of feveral pieces 
joined together, and fiiue have fealy fheaths, and fome have flefhy 5 
fome are terminated with a fort of large lips, and others have none a 
all; but in maity kinds, thefe varieties cannot be diftinguifhed without 
a microfcope. However the carriage of the trunk may be plainly feeB 
by'the naked eye; for {ome fold them up when they are not ufed, am 
others, while they are in ation, keep them turned downwards ; as fof 
inftance, Bees and Drones; in fhort others always keep them at ful 
length, only they can turn them to different fides, as may be feen 1# 
Goats, Grafshoppers, and the like. The thape of the head of all fort® 
of flies are not alike, for fome have them almo round, others broadef 
than long, and of a lefs diameter before than behind. The Formica~ 
Leones differ from the Pucerons, not only in their feelers, but in thel® 
double corflet. The corflet of fome Flies is much higher than in other 
infomuch that it obliges them to turn the head downwards, and make? 
them appear bunch-backed. All Flies have but fix legs, but they dif 
fer in the fize in proportion to the body; for fome have them very longs 
and others very fhor:, as for inlance, the Gnats and the Tipule feem ny 
be mounted upon ftilts, The legs of moft Flies are joined to the corflet” 
but in fome, one of the pairs is attached to one of the rings of the body, 
Betides, the latter part of the body ferves for another diftina@ion 
Flies, for fome are armed with (tings, and others have a fort of pierce!” 
lodged in a cafe. Others are provided with a kind of faw, which dog 
not appear till the body is prefied. Likewife fome have firings at the? 
tails, as the Ephemera. Mot 
