Of the frejh JVater Polype. 169 
hath found on the bodies of divers animals, as on the 
fhells of friails, &c. 
The belt way to find them, is to take up the different 
bodies and put them in glaffes full of water, and if there 
are any polypes, they will foon be perceived adhering to 
thofe bodies and moving their arms. 
Mr. Trembley hath alfo taken the trouble of going 
often to the fides of thd ditch in which he found them, 
at a time when the fun fhone upon the bottom of the 
water, and chofe thofe places where the water was clear, 
and that had an eafy declivity, and fays, he hath diftin&ly 
feen them at the bottom of the water, on all the bodies 
that were therein, and on its fuperficies; by which means 
he acquired thofe ideas concerning them, he could never 
have attained to without this precaution. 
The moft common pofture they are generally found in, 
whether in their ordinary places of abode, or in glaffes, is 
reprefented by the figures 331. and 332. The pofterior 
end b, of the polype a b, is fixed againft a plant e f, 
fig. 331. or againft a ftraw g h, fig. 332. the body a b, 
and arms a c, being extended in the water. 
The general figure of the polype’s body in this atti¬ 
tude is not perfectly the fame; in the three kinds of po¬ 
lypes here deferibed, the body of the green ones, fig. 331. 
diminifh from their anterior to their pofterior end, the 
diminution being almoft infenfible. 
That fort reprefented fig. 332 are the fame 5 but thofe 
of the third fort, fig. 333. differ from the two preceC' <g 
ones in this refpeeft, that their body does not dimini x - 
fenfibly, but from the anterior extremity a, to th 7 
and fometimes even to two thirds of the length :* 
body; as at d, fig. 334. becoming from this poire 
finer, and do not diminifh from thence to the pc 
end. They wave their arms in all directions, as at a, 
