4.0 
ficht, and may be compared to the turning of 
a wheel about the axle-tree of a chariot. 
In regard, therefore, of the motions before 
explained, by which this little animal feems to 
approach rather to the nature of Fleas than, 
Lice ; and on account of its wonderful arms, 
which are made like the boughs of a tree, I 
think it may be properly called, as I have 
named it, the Arborefcent Flea. 
The ftructure of this infec’s belly likewife 
deferves as much confideration as its breaft and 
arms: if we view it on the outfide, it will 
f{eem to be of arhomboidal form ; butin reality, 
the part which refembles the belly, is nothing 
more than a tranfparent skin full of {eales or 
fhells, fig. 11, d, which is joined together in the 
back or pofterior part of the body, but in the fore 
part is divided into two fegments which open 
from each other; and thus it forms, as it were, a 
little open cafement, through which the animal 
can move his real belly and tail in and out. 
Therefore this rhomboidal skin which covers 
the infect, is only its fhell, through which its real 
body is feen, as this fhell is tranfparent. ‘This 
fo far agrees with the teftaceous animals; but 
it differs from them widely with refpect to its 
diftin@tly vifible motions, which it has with 
the abdomen and tail. I have often obferved 
that it ftretched out its tail through the open- 
ing in its skin or fhell beforementioned, and 
pulled it in again. This fubftance, or. the 
body and tail, are waved and turned round 
like the letter S; in the middle is feen a {mall 
tranfparent inteftine, and in the fore part are 
feen feet which aretranfparent, formed almoft 
in the fame manner as the articulated briftles 
in Shrimps, arid having the like, as it were, 
tremulous or jumping motion, wherewith this 
animal, as well as the Shrimp, can change its 
place; though this office is performed in gene- 
ral by its arms, to which, however, the legs 
f{eern to be fomewhat affiftant. The extremity 
of the tail is divided into two fharp and {tiff 
briftly hairs f, on which, at a little diftance, 
grow two other fimilar ones. The eggs 
are placed on the back of the body, which I 
affirm as certain for this reafon, becaufe, foon 
after this infect hath caft them out, very {mall 
whitith infects are feen fwimming in the wa- 
ter, which are of the fame nature with the 
full grown ones, nor do they undergo any other 
change, except that they grow bigger; as I 
have {hewn to happen to Lice, in the example 
of the changes of the firft order. 
In figure 111 I fhew all the parts hitherto 
defcribed, except only the eggs which are 
caft out, with this difference, that a little of 
the fore part of the body, which was before 
reprefented laterally, is here delineated ; fo 
that the motion of the inward. body and tail 
through the rhomboidal fhell, or skin, may~ 
be feen the more exactly. The feet alfo may, 
by this means, be feen more plainly, being 
here ftretched out beyond one fide of the skin ; 
which I fhall make more clear, and explain 
more particularly hereafter by letters, 
The BiO;OK? of N Ao WE tee on 
The colour of this infect inclines fomewhat 
to red in the full grown; and is like that of 
beef, which has been fome time fteeped in 
water. The outward ftructure of the skin 
that covers it agrees, in fome meaftire,; with 
the reticulated and checquered fhell skin of 
the {caly fifh ; though I could hitherto fee no 
{cales in it, having never viewed it through 
thicrofcopes, which, in the moft powerful 
manner, magnify the bulk of objects: but it 
is tranfparent like the skin of the Shrimp, or 
as the fhells of very {mall Mufcles and young 
Cockles. The extreme part of the branching 
arms is like Hen’s feet, but their divifions are 
not fo difting. 
I have frequently the infe& I have been. 
hitherto defcribing, in cifterns of rain water, 
when no rain hath fallen for a long time; but — 
when thefe infects have plenty of rain, they 
can fcarcely be feen, becaufe they divide 
themfelves here and there to every quarter. 
I have found them likewife in running water, 
and in moorifh or fenny ditches, wherever any 
of the clear water has ftagnated on the fedi- 
ment at the bottom. They fometimes remain 
feveral days on the furface of the water, and 
fometimes are feen at the bottom only ; but 
we feldom or never fee them at reft. They 
change their skin like Lice, and the caft skin 
refembles the infect itfelf fo exactly, that you 
would fay, you faw it alive. I keep by me 
fome skins of this fort, which are very 
curious. eye 
I remember when I was in France, in the 
foreft of Vincetines, that I faw fo great a num- 
ber of thefe infects in a watering-place for 
horfes, that the water appeared as if changed 
into blood; which, indeed, terrified me at firft, 
but it afterwards gave me an opportunity of 
inveftigating the nature of thefe infects more 
accurately, and made me cautious not to pais 
too rafh a judgment on things that are obvious 
and familiar to us; for this leads us into in- 
numerable errors and prejudices. It is not 
impoflible that thofe who affirm that bloody 
rain has fallen, have been deceived in the fame 
manner. Is it not poffible, that fuch red 
drops might iffue from infects, at the time they 
come frefh from the Nymphs, which diftil 
a bloody fluid? This feems to happen, efpe- 
cially when fuch infects are more than ordi- 
narily multiplied in any particular year, as we 
often experience in the Butterflies, Flies, 
Gnats, and others. 
The celebrated Florence Schuyl, who was 
profeffor of phyfic in the univerfity of Leyden, 
long after this incident communicated to me 
the like obfervation concerning bloody rains. 
He informed me, that being once intent on 
his ftudy, he heard a noife, of which, as it 
increafed by degrees, he -was defirous to know 
the caufe; and that he was foon fatisfied in 
this particular, for that one of the maid-fer- 
vants ran up to him, and told him, in an in- 
terrupted fobbing tone of voice, that the waters 
of Leyden were turned into blood. Upon 
this, 
