Animalcules with Shells and Wheels . 297 
Immediately to the lower Part of the 
Head the Thorax is joined, feemingly of 
a mufcular Contexture, and containing with¬ 
in it an Inteftine, which by its Motions mull 
be either the Lungs or Heart of the Ani¬ 
mal ; fee b.fg. 4. and 5. 
A Communication between the Thorax 
and the Abdomen or Belly is continued by 
Means of a fhort Veffel c, whofe alternate 
Contractions and Dilatations occafion the 
Abdomen to rife and fall alternately, having 
at the fame time a Sort of periftaltic Mo- ! 
tion. Through this Veffel or Gut all the 
Food the Animal takes in is conveyed direCt- 
ly'to the Abdomen, where it becomes digefl- 
ed, and is then difcharged by the Anus, which 
is placed fomewhere near the Tail; but we 
have not yet been able to difcover exactly 
where, for the Faces are thrown out fome- 
times at the lower Opening of the Shell, 
and fometimes they are carried upwards 
(between the Shell and the Body of the 
Animal) and cafh out with a confiderable 
Force at the other End, by the Motions of 
the Fibrillce , which the Animal can employ \ 
to form a Current, not only towards him 
but from him. 
The Tail has three Joints, and is cleft or 
divided at its Extremity, by which Means it 
can the better fallen to any Thing. It is feen 
moft commonly iffuing through the Hole 
at the lower End of the Shell, wagging nim- 
My 
