a 
The H. f $yTrO; Ri ¥« of, INS HE T.8. ay 
a confiderable pit or hollow in the water; 
whilft the tail itfelf affumes the figure of a 
glafs, wide at top, and ending at the bottom 
ina point. Hence it is manifeft, that this tail 
ferves the Worm for both the purpofes of 
fwimming and breathing. ‘Thus then, O won- 
der of wonders! this creature receives by its 
tail the univerfal principle of life and motion 
in animals. And the better to anfwer fuch an 
important ufe, thofe hairs are fo myfterioufly 
conftructed, that, let them lie under water 
ever fo long, they never contract any moifture, 
the water running off of them the very mo- 
ment they reach the furface. Another advan- 
tage the Worm has in thefe hairs, is, that, 
when fwimming, it can by means of them 
immediately {top itfelf, and fo remain quietly 
fufpended in the water as long as it pleafes. 
Ce A Bad. 
Of the attions or motions of this Worm; the places where it is found, its food, 
and the manner of killing it for diffection. 
HE motions which this Worm makes 
& in fwimming are extremely beautiful, 
efpecially when it advances with its whole 
body floating on the furface of the water, after 
filling itfelf with air by the tail. To fet out 
in this pofture, it firft bends its body to the 
right or left; then contra¢ts it in form of the 
letter (S); and laftly, or lying flat upon its 
belly, it ftretches out the body again to a 
ftraight line. By thefe alternate bendings, con- 
tractions, and extenfions, it moves along upon 
the furface of the water; and as its motions 
are very flow, it will hold out for a long time 
in this manner. 
Thefe Worms are no way difturbed on 
being handled in the water; though they can- 
not fuffer the touch of other Worms, even 
‘thofe of their own f{pecies, without agitation, 
when fwimming amongft each other. From 
this circumftance we may conjecture, that they 
are provided with a ready inftinct to difcover 
whether what comes in their way is likely to 
do them any harm. Be that as it will, I drew 
great advantages from this quiet difpofition of 
the infect, as it afforded me the better oppor- 
tunities of examining it by the microfcope, and 
making a {atisfactory figure of it. 
At the time when thefe Worms float on the 
furface of the water, it is impoffible to drive 
them under it, fo as to make them continue 
there, on account of the great quantity of air 
with which they are then fwelled. But on ex- 
pelling this air by the tail, they of themfelves 
immediately fink to the bottom; nor can they 
again make thermfelves float on the furface of 
the water, till, having rifen to it, they expand 
the hairs of their tail, and take in another 
draught of air. 
On taking thefe Worms out of the water, 
all their motion feems confined to the head, 
becaufe it is only by the help of their legs, 
which are fituated there, that they can ftir in 
this fituation. But as it is neceflary, for that 
purpofe, that the head fhould bend at the fame 
time, one would, at firft, imagine they make 
ufe of their mouth to walk with ; whereas, in 
reality, their progrefs is entirely effected by the 
feet only. 
' Thefe Worms are to be found about the 
beginning of June, fooner or later, according 
as 
as the fummer is more or lef{s warm, both in 
falt and frefh waters. Sometimes great num- 
bers of them offer themfelves, as it were, of 
their own accord to our inquiry; whilft in 
other years, it is no eafy matter to meet with 
them. They are common enough in the 
ditches of grazing grounds, efpecially in fuch 
parts of thofe ditches as here and there con- 
tain little patches, or iflands, covered with 
grafs and other plants, through which, and 
upon it, thefe Worms love to crawl. They 
are often too, to be feen in the cracks of our 
ditch-banks, where they float upon the furface 
of the water, by means of their tail, with 
head and thorax hanging down: and in this 
fituation they will turn over the clay and, dirt 
with their feet and their fhouts, as thofe parts 
are fo near each other, in fearch of food. 
It is thus thefe Worms look out for their 
nourifhment, which is principally a kind of 
vifcous matter, to be met with in little pools, 
and about the fides of ditches; for thefe in- 
fects are never feen in large and deep waters, 
fo that, whenever it happens that the ditches 
are quite full, the Worms, to come at their 
food, either betake themfelves to the bottom, 
or venture on fhore, in queft of fomething to 
live upon. It is very remarkable in thefe in- 
fects, that, when they lie under water, they 
very often drive air into the cavity formed by 
the hairs of their tail ; which cavity, on being 
thus blown up, looks like a tranfparent pearl 
moving in the waters; at the fame time that, 
by becoming the lighteft part of the infec, it 
keeps uppermoft, and thereby affords the feet 
and the {nout a better opportunity of providing 
for the infect’s fupport. 
This little infect is exceeding harmlefs ; it 
neither bites or wounds, or otherwife does any 
mifchief ; contrary to the opinion, one might at 
firft fight be apt to form of it, on account of the 
furprifing vibrations of the legs, placed in its 
head, which fo much refemble the brandithings 
of anenvenomed tongue or fting: but fuch no- 
tions appear altogether wrong on further examina- 
tion; for the opening of the infe@’s mouth, at 
which it fucks in its food, is feated within the 
bending of its fharp pointed and crooked fnout. 
I find that clay and foft earth are the food of 
this infect; though I have likewife fometimes 
found 
