The EPI ST OrR Wr of 1 N'S BOT &, 43 
what obfcure and confufed manner: this is ow- 
ing entirely to the foftnefs and delicacy of its 
fkin, which fticks clofe to the furface, and ac- 
commodates itfelf to the fhape and figure of the 
enclofed Nymph. : 
By duly attending to the preceding obfervati- 
ons, we may for the future eafily underftand, for 
what reafon fome of thefe Nymphs retain the 
figure of their former Worms more than others ; 
for, it will plainly appear, that this difference arifes 
folely from the fkins of the former Worms, be- 
ing more or lefs hard or pliable. For thofe 
Worms, that have a very dry and hard -{kin, as 
the Worms of the common bog-houfe Fly, and 
the Mufca Afilus, or Gad-fly, cannot but retain 
their former appearance; whilft other Worms of 
a foft and delicate skin, cannot but lofe a great 
deal of it; all which is made evident, by a re- 
markable example in the tenth figure, under the 
letter E. 
Such being the nature of thefe things, we may 
plainly perceive how much thofe naturalifts were. 
miftaken, who called the foregoing condition of 
the limbs, and other parts, a tue egg, as may 
be feen in Mouffet, and Goedaert, in the com- 
mentators of this laft, and many other authors. 
But let no one imagine, that I mention this mif- 
take, in order either to expofe the writers, who 
have committed it, or to deferve glory from their 
ignorance: my fole intention is to publith truth, 
and excite thofe who love it, to fearch after it in 
the works of nature themfelves; for they are 
capable of teaching us more in a fingle moment, 
than all the written accounts of them could do 
in a thoufand years: but then we fhould prepare 
ourfelves for fuch an inquiry, particularly by lay- 
The Jurprifing biffory of the infeé# called the Mufea Tabanus, 
ing afide all manner of prejudice, as it plainly 
appears, that obfervations attempted upon a 
wrong foundation, have only ferved to produce 
a great number of pernicious errors. 
To conclude, I prefent the reader, under the 
letter F. of the fame figure x. a reprefentation of 
the Fly produced from the Nymph I have been 
lait defcribing. It is like the common Fly, di- 
vided into the head, the thorax, and the belly. 
Between the eyes, which are feated in the head, 
and are of a deep purple colour, are two filver 
borders or zones ; and between thefe borders are 
placed a pair of antenne, or horns, From the 
fhoulder-blades arife two grayifh membranaceous 
wings, and from the fore-part of the thorax, fix 
hairy legs. ‘The abdomen is covered with hair, 
like briftles, and is divided by feveral rings, parted 
from each other by black rolls or bandages. This 
Fly, like the preceding, on its quitting the 
Nymph-ftate, leaves two skins behind it, 
A\s to the manner in which this {pecies depofits 
the eggs within the Carerpillar, reprefented in ° 
No. Ill. of the xxxvutth Table, and the courfe 
in which the Wormsarifing from thofe eggs, are 
changed into Chryfallides with the Caterpillar, 
upon which they feed; or, to fpeak more-pro- 
perly the manner in which thefe fmaller Worms 
come to be enclofed in the Caterpillars Chryfalis, 
and their management in forcing their way thro’ 
this Chryfalis, I fhall give a general account of 
in the progrefs of my furvey of this fourth order, 
and hope I may fome time, or another, have an 
opportunity of handling this fubje@ more parti- 
cularly, and folving the gordian knot which it 
contains. 
or, more properly, 
the Afilus or Gad-fly *. 
Bere Tse NRO DUC oh le Onin: 
HE Infect, whofe hiftory I am about to 
give under the name of the Gad-fly, is fo 
wonderful in all its parts, that it may be well 
ranked amongft the moft mafterly works of na- 
ture; for, the particulars which induftrious ob- 
fervers have difcovered in it, are moft fingular, 
and unheard-of in other kinds. The learned 
Mouffet inveighs feverely againft thofe authors, 
who confound this Fly with the Tabanus or 
Breeze-fly, as he affirms there is an effential dif 
ference between them, which I have myfelf alfo 
found to be very true; for, as the faid Mouffet very 
pertinently alledges after Ariftotle, the Afilus or 
Gad-fly, proceeds from a certain little, broad and | 
water infect. This author remarks alfo, with 
equal propriety, that the Afili or Gad-flies -are 
much more fcarce than the Tabani or Breeze- 
flies, and they are not to be found except in the 
neighbourhooud of rivers, and they have a much 
larger probofcis or trunk than the Tabani or 
Breezes. ‘This being fettled, the Fly that Yam 
here now about to defcribe, is a true Afilus or Gad= 
fly, and ought, by no means, to be calleda Taba- 
nus, ot Breeze-fly ; for, agreeable to the defcrip- 
tion given of the Afilus, or Gad-fly, it proceeds 
froma little flat water Worm ; it flies about flelds 
near waters; and, in fine, it has a larger trunk than 
the Tabanus or Breeze-fly, Mouffet has given us a 
true figure of the Tabanus or Breeze; and at the 
fame time, has afligned the real difference be~ 
tween that and the common Horfe-fly ; for there 
are many {pecies of Horfe-flies, and the Tabanus 
or Breeze ought to be accounted one of them, 
But Mouffet is greatly miftaken in giving the 
Afilus a hard fnout, with a {trong fting or acu 
leus fixed to the fore-part of it, thefe particulars 
being obfervable in the Tabanus or Breeze-fly 
Only. He errs as much in faying, that the Ta- 
banus grows at the end of honey-combs, But 
it was impoflible, that this author thould not 
* ‘The common writers have been very confufed in their accounts of the two fpecies of infe&s known by the names of the Gad- 
fly and the Breeze-fly, and have applied the names at random, to one or the other. 
The Latin denominations of the fame infects, 
‘Tabanus and Afilus, have been as ill defined. The creatures are perfectly diftin@, bothin the Worm and Fly-fate nd, ’ti 
5 a > % ix >» and, ‘tis t b 
hoped, that, for the future, they will be fo underftood and confidered, this author having perfectly aitnteuittied the words, aa ie 
certained theiy meaning by his figures. 
2 
& 
com~ 
