Sub-order I.—Schizogregarinae.

Forms in which schizogonic reproduction is of general occurrence during the extra-cellular, trophic phase. Three genera, Ophryocystis, Schizocystis and Eleutheroschizon, different peculiarities of which have been referred to above. Mostly parasitic in the intestine or Malpighian tubules of insects. (In this type of parasite, as exemplified by Ophryocystis, the body was formerly wrongly considered as amoeboid, and hence this genus was placed in a special order, the Amoebosporidia.)

From Wasielewski, after Léger.
Fig. 16.—Spores of various Gregarines.

a, Eirmocystis, Sphaerocystis, &c.

b, Echinomera, Pterocephalus, &c.

c, Gregarina, &c.

d, Beloides.

e, Ancyrophora.

f, Stylorhynchidae (type of).

g, Menosporidae.

h, Gonospora terebellae.

i, Ceratospora.

k, Urospora synaptae.

Sub-order II.—Eugregarinae.

Schizogony very exceptional, only occurring during the intracellular phase, if at all. Gregarines fall naturally into two tribes, described as cephalont and septate, or as acephalont and aseptate (haplocytic), respectively. In strictness, however, as already mentioned, these two sets of terms do not agree absolutely, and whichever set is adopted, the other must be taken into account in estimating the proper position of certain parasites. Here the cephalont or acephalont condition is regarded as the more primary and fundamental.

Tribe A.—Cephalina (practically equivalent to Septata).

Save exceptionally, the body possesses an epimerite, at any rate during the early stages of growth, and is typically septate. Mostly intestinal parasites of Arthropods.

The chief families, with representative genera, are as follows: Porosporidae, with Porospora gigantea, at present thought to be gymnosporous; Gregarinidae (Clepsydrinidae), with Gregarina, Clepsydrina, Eirmocystis, Hyalospora, Cmenidospora, Stenophora; Didymophyidae, with Didymophyes; Dactylophoridae, with Dactylophorus, Pterocephalus, Echinomera, Rhopalonia; Actinocephalidae with Actinocephalus, Pyxinia, Coleorhynchus, Stephanophora, Legeria, Stictospora, Pileocephalus, Sciadophora; Acanthosporidae with Acanthospora, Corycella, Cometoides; Menosporidae with Menospora, Hoplorhynchus; Stylorhynchidae, with Stylorhynchus, Lophocephalus; Doliocystidae with Doliocystis; and Taeniocystidae, with Taeniocystis. The curious genus Selenidium is somewhat apart.

Tribe B.—Acephalina (practically equivalent to Aseptata, Haplocyta).

The body never possesses an epimerite and is non-septate. Chiefly coelomic parasites of “worms,” Holothurians and insects.