zgS Animalcules with Shells and Wheels. 
bly to and fro, and is made ufe of in fwitu¬ 
rning to fteer or direcft its Courfe : but when 
the Water wherein the Animal abides is al- 
moft dried away, or when it has a Mind to 
Compofe itfelf to reft, it contracts the Head 
and Fore-part of the Body downwards, and 
pulls the Tail upwards, in fuch a Manner 
that the whole Animal is brought intirely 
within the Shell: and at fuch Times only 
the anterior Edges of the Shell, and the 
Spikes proceeding therefrom, can be fully 
diftinguilhed, and determined to be as repre¬ 
sented Jig . 6 . whofe Defcription was juft now 
given. For the Shell is fo extremely tranf- 
parent that its Terminations cannot be feen 
when the Inledl extends beyond it; but 
whatever paffes within it is as plainly viiible 
as if there was no Shell at all. 
Fig. 7, S, 9, and 10, (hew the feveral 
Appearances of the fecond Species of thefe 
{helled Animals having Wheels, which dif¬ 
fers from the ftrft in fome Particulars now 
to be de-fcribed. 
The Body of this Species conftfts of three 
Parts, in like Manner as the other does; only 
the Thorax and Al}domen are not in this 
feparated by a Gut or intermediate Veftel as 
they were in that, but are joined immediately 
together and at that Place in the Thorax, 
where, in the other Species, I have defcribed 
an Inteftine, which I fuppofed to be either 
the Lungs or Heart, an Heart is plainly per- 
1 o ceived 
