34 ZOOLOGY 
emerging and living parasitically in the various cavities of 
their host. The Coccidiidea pass their whole life as cell 
parasites. The true Gregarimes are divided into the Mono- 
cystidae, whose body is not divided into two chambers, and 
which inhabit Annelids, Gephyrea, Platyhelminthes, and Tuni- 
cata; and the Polycystidae, in which a transverse partition 
divides the cell into an anterior and posterior chamber, the 
latter invariably containing the nucleus. An anterior outgrowth, 
the epimerite, which serves to attach the Gregarine to the tissues 
of its host, is often present, but this is shed sooner or later. 
The Polyeystidae have hitherto only been found in the 
alimentary canal of Arthropods. 
Monocystis magna (Fig. 27) is frequently to be found with its 
anterior end embedded in one of the epithelial cells of the en- 
AS) 
YS) 
Fic. 27.—Five individuals of Monocystis magna (Schmidt), with their anterior 
ends embedded in the cells of the rosette-shaped inner end of the vas deferens of 
Lumbricus terrestris. 
1. Part of the vas deferens of JZ. 3. The nucleus. 
terrestris. 4. The ectoplasm. 
2. The endoplasm of the Gregarine. 5. The cuticle. 
larged inner rosette-shaped openings of the vas deferens of the 
common earthworm. It is visible to the naked eye, and 
sometimes attains a length of 5 mm. The body is limited by 
