THO. SR tOWOER took 
In the fifteenth place, I mutt infert in this or- 
der, all thofe infects that change, as it were, into 
a kind of web. ‘To this clafs or order, more 
particularly belong thofe little Worms, whofe 
web is fo fine, tender, and delicate, that a per- 
fon muft have great practice in things of this 
kind, to open it without breaking, Within this 
web, the Worms change to very {mall Nymphs. 
I therefore refer to this order Goedaert’s Flies, pro- 
duced from the genuine Nymphs of Worms, 
. Which the faid author tells us in his xith Expe- 
riment, Part I, crept out of the body of a Ca- 
terpillar that fed upon cabbages, and then made 
themfelves each a neft of a yellow filk, in which 
they afterwards {hat themfelves up. But Goe- 
daert knew nothing of the Nymphs of thofe 
Worms, as appears by all that. he fays in the 
place already cited. Nor was accurate Mr. Ray, 
Catalog. Plant. page 137, already mentioned, 
happier upon this occafion than Goedaert, whofe 
obfervations he was acquainted with. This 
gentleman imagined, that the Worms here 
{poken of, lay hid within their webs in the form 
of Worms: he even went further, and commit- 
ted another miftake, in thinking that the eggs 
of thefe infects, diftinguifhed by annular incifi- 
‘ons, were real Nymphs, and not their ob- 
long tranfparent eggs: for thofe alone are Ver- 
miform-Nymphs, though both in reality certain 
genuine Nymphs not as yet vifible. I have fome- 
times alfo obferved Worms, which form for 
themfelves under ground an oviform cafe or 
fheath, which a perfon, not acquainted with 
things of this nature, might eafily miftake for a 
Vermiform-Nymph. 
Moreover, I give a place in this order to fuch 
Nymphs of Worms or Caterpillars, as are found 
upon the leaves of willows, enclofed in a very 
fine and delicate covering, or web of the fame 
kind. 'Thefe Nymphs are changed in time toa 
very delicate Fly, which the curious may fee 
together, with its web or covering, among my 
other curiofities. 
Laftly, I refer.to this order the genuine 
Nymphs of a kind of Worms, which having 
made their way through the Caterpillar’s fkin, 
38 
Ni ADT REE 5 ale, 
upon the flefh of which they had fed, not only 
{pin themfelves a covering of white filk, but for- 
tify it with a kind of cottony fubftance, which 
the parent Caterpillar had formed for its own 
ufe; and ina few days after this operation, force a 
paflage through both thefe enclofures in the form 
of Flies. I preferve in my colle€tion almoft all the 
different kinds of Flies hitherto mentioned, with 
their coverings or webs, fo that I can give, ina 
manner, an occular demonftration to thofe who 
defire it, of every thing that I have advanced con- 
cerning them. I have, befides thefe, many other 
kinds of webs, which my defire of making a 
fpeedy end of this fubject, hinders me from 
enumerating at prefent. 
I may include, in this order, in the fixteenth 
place, all the genuine Nymphs which have arifen 
from Worms, which undergo their changes 
within very flender and delicate habitations of 
their own forming, and which they conftantly 
carry about them, as {nails do their thells, till 
at laft they change to Flies, and again betake 
themfelves to the open air. I preferve, in my 
Mufeum, a great variety of fuch Flies, and their 
‘Nymphs and Worms, together with the furprif 
ing cafes of the latter, in which they lie hid, and 
wherein they walk about with, fome in the 
earth, and fome in the water. Some of thefe 
Worms are mentioned by Aldrovandus, who 
defcribes them by the name of Xylophthori, or 
Worms that deftroy timber. I have likewife 
fome Flies which are produced from thefe 
‘Worms, a few of which have been already de- 
{cribed under the name of Ephemeri. — Laftly, 
it muft be remarked here, that all the Nymphs 
of the fourth order, may truly be reckoned of 
the third, if we confider them in themfelves 
alone, and without paying regard to their dkins, 
which they do not caft, or the webs and hidden 
cafes, in which they conceal themfelves. 
Thus I fhall finith this enumeration, and ge- 
neral defcription ot the infects of the fourth or- 
der, which I ihall hereafter more particularly 
treat of, and illuftrate by juft and careful hifto- 
ries, and convincing examples, 
«% 
A fingular example of the fourth order of mutations, exhibited in a Fly; whofe 
metamorphofis, or natural accretion into the firft form of its limbs, and other 
parts, I call a Vermiform-Nymph. 
. Tas. XXXVIII. 
Neo il be HE Worm of the common Fly of 
our privies or boghoufes, repre- 
fented of its natural fize, and as it appears un- 
der its firft coat or fkin, in which form it is 
called an egg. This firft figure exhibits the 
egg, as viewed with the afliftance of the mi- 
crofcope. 
N°. II. The double coat or fkin of the egg, 
which fkin or coat the Worm leaves behind it, 
when it is hatched; or, in other words, creeps 
out of it. This coat is reprefented as magni- 
fied by the microfcope, to twice its natural 
fize. 
. N° VII. The Worm itfelf, fomewhat bigger 
than it really is, when it has juft crawled out 
of the membrane, in which it was concealed 
under the form and name of an egg. 
‘“N°&. IV. The fame Worm, arrived at its full 
growth, and crawling about. As the feet of 
this Worm are very fhort, and narrow withal, 
it always moves, and, as it were, draws itfelf 
forward by the help of its head or beak: there- 
fore, if you put it on a fmooth piece of glafs, 
it walks with great difficulty; whereas, upon a 
coarfe cloth, it will advance pretty brifkly ; for 
it thrufts its head into the little hollows and 
cavities of the cloth, and very nimbly draws 
up 
