B. sphærica, medio pellucentissima. Spherical bursaria, very pellucid in the middle.
A subspheric hollow animalculum, the lower end furnished with black molecules of various sizes, the fore-part with obscure points, the rest entirely empty, and the middle very pellucid; it moves slowly from right to left.
XI. CERCARIA.
Vermis inconspicuus, pellucidus, caudatus. An invisible pellucid worm with a tail.
124. Cercaria Gyrinus.
C. rotundata, cauda acuminata. Round cercaria, with a sharp tail.
It has a white gelatinous body, without any traces of intestines; the fore-part somewhat globular, the hind-part round, long, and pointed; sometimes it appears a little compressed on each side. When swimming, the tail is in a continual vibration, like that of a tadpole. It seems very similar to the spermatic animalcula.
125. Cercaria Gibba.
C. subovata, convexa, antice subacuta, cauda tereti. Somewhat of an oval shape, convex, the fore-part rather acute, the tail round.
It is a small animalculum, gelatinous, white, opake, and without any visible intestines; the upper part convex or gibbous; many of them were found in infusions of hay, as well as of other vegetables.