minating in two pellucid thorns; fometimes a fwelling is perceived
between thefe. It often projects from the incifion at the-
apex, a kind o f cloven probofcis. Is found in water where there-
is duck-weed, d d the points o f the fore-part, e the probofcis.
138. Cercaria Forcipata.
Cercaria cylindrica, rugofa, probofeide forcipata cxfcrtiii,
eauda bicufpidata.
Cercaria cylindrical, wrinkled, with a forked probofcis, that is:
1 can thruft out, or pull in.. It is found in marlhy fituations.
139., Ceitaria Pleuroneftes. Fig. 38, Plate XXV.
Cercaria orbicularis, cauda unifeta.. Orbicular the tail, confiding
o f one briftle.
It is membranaceous, rather round, and white. In the forepart
are two blackilh points. The hind-part is furnilhed with a>
flender fharp tail. In the middle are orbicular inteftines o f different
f i zes the larger o f them are bright- It s motion is;
vacillatory; in fwimming, one edge of the lateral membrane is:
upwards; the other, folded down. Found in water that has been
kept feveral months.
140. Cercaria Tripos.. Fig. 38, Plate XXV.
Cercaria fubtriangularis, brachiis deflexis, cauda refla. Cercaria
fomewhat of a triangular form, two. bent arms, andaflrait
tail-
The body flat, pellucid, triangular, each angle- of the bafe of
the triangle, or fore-part thereof, being bent down into two
linear ears, or arms ; the apex o f the triangle is prolonged into a.
141. Cercaria Cyclidium,
Cercaria ovalis, poftice fubemarginata, cauda exterHli, This is
oval, the hind-part fomewhat notched, with a tail, that it thrufts
out at pleafure.
It’s body is oval, finooth, membranaceous, pellucid, with a
black margin. The tail | not fixed rio the edge, but concealed
under it and coming out from it at every motion, and yet fo as.
to proje’a butlM. Fro„ A . edge.
the hinder-part. Ks inteffine, .r e ,= ^ P «
quently found in pure water.
142. Cercaria Ten ax.
c e r e .» membranacea, « * e E g « « j g f e