Below the thorax there is an annular circle that joins the thorax
to the abdomen. The abdomen is much the largeft part of
this animal, it contains the ftomach and vifcera. When this
creature is full o f food, the bowels are opake, and o f a crimfon
colour, extending from the thorax quite through the belly and a
great part of the tail, and exhibits a fine view o f the periftaltie
motion, or thofe gradual contraftions and dilatations o f the intef-
tines, which propel their contents downwards. There are many
ramifications o f veflels, both longitudinal and tranfverfe, round
the bowels. It can extend the abdomen in length very much, or
contraft and widen it confiderably, fo as to become a cafe for all
the reft o f the body. The tail goes from a joint at the lower part
o f the belly to the pofterior extremity; it is of a tapering form,
and confifts generally o f three joints; when it is inclined to fix
itfelf to any thing by the tail, it thrufts out four, fometimes fix,
little hooks from the end thereof; thefe are placed in pairs, one
pair a t the very extremity itfelf, the other two a little way up the
fides; the three are feldom feen at the fame time. The wheels
feem to be the organ that the animal ufes to aflift it in fwimminso'.
All the aftions of this creature feem to imply lagacity and
quicknefs of fenfation: at the leaft touch or motion in the water
they mftantly draw in their wheels. Mr. Baker conje&ures that
they have eyes lodged near the wheels, becaufe while they are in
the globular or maggot ftate, their motions are flow and blundering
; but after the wheels are protruded, they are performed with
great regularity, fwiftnefs, and fteadinefs.
Pig. 17, Plate XXVI. A, reprefents this little animal in what
Mr. Baker calls the maggot ftate; while in this form fmall fpiculas
are feen to dart out near the anterior part; the fnout is fometimes
more and fometimes lefs acute than in this delineation, (a) a
fmall horn near the thorax.
Fig. 15 reprefents it’s manner o f moving from place to place,
while in the maggot ftate.
Fig. 12 exhibits it, with the two femicircular parts, put out,
and in the pofture it places itfelf in when it is preparing to fwim
about, or going to put it’s wheels in motion.
Fig. 1 {hews the head at it’s full extent, with a couple o f fmall
bodies on the top of it, armed with fmall teeth like thofe o f the
ballance-wheel o f a watch.
At Fig. 18 the interior parts are more particularly exhibited,
(a) the circle from which many veflels originate ; jh)the thorax, or
breaft, joined to the head by the neck (c.) The part which is fup-
pofed to be the heart is plainly feen at (d.) The abdomen (f) is
feparated from the breaft by a ring (e)> (g) the tail.
Fig. 19 is the wheel animal, not full extended, but yet working
it’s wheels about.