Fam. Polysporocystidae, Léger. The oocyst contains numerous spores.
There are several genera with monozoic spores, characterized by variations in the form and structure of the sporocysts, e.g. Barroussia, Schn. (fig. 8), Echinospora, Léger, and Diaspora, Léger; most of these forms are from Myriapods.
Genus Adelea, Schn. Dizoic spores; sporocysts round or oval, plain. Several species are included in this well-known genus, among them being A. ovata, A. mesnili, A. dimidiata; most of them are parasitic in Insects or Myriapods.
Genus Minchinia, Labbé. Dizoic spores; the sporocysts are produced at each pole into a long filament. M. chitonis, from the liver of Chiton (Mollusca).
Genus Klossia, Schn. The spores are tetrazoic (or perhaps polyzoic). K. helicina from the kidney of various land-snails is the best-known form. Usually said to have 5 to 6 spores, but Mesnil considers that the normal number is 4, as is the case in another species, K. soror.
Genus Caryotropha, Siedlecki. Many spherical spores (about 20) each with 12 sporozoites. C. mesnilii, unique species, from the spermatogonial (testis) cells of Polymnia (a Polychaete). An interesting point in the schizogony is the formation of schizontocytes (see above).
A Coccidian parasitic in the kidneys of the mouse has been described by Smith and Johnson (1902) and named by them Klossiella, on the ground that it possessed many spores, each with about 20 sporozoites. Woodcock has shown, however, that the authors were in all probability dealing with a similar modification of schizogony to that which obtains in Caryotropha. The sporogony of this form (and hence its systematic position) remains at present, therefore, quite unknown.
There are several doubtful or insufficiently known genera, e.g. Bananella, Goussia, Hyaloklossia, Gonobia, Pfeifferella and Rhabdospora, many of which probably represent only schizogonous generations of other forms. (For information concerning these see Labbé, 1897.)
Lastly it remains to mention the extremely interesting forms parasitic in Cephalopods. For some years these have provided a fruitful source of discussion to systematists. Here it may be stated simply that their systematic position and nomenclature were thought to have been finally settled by the researches of Jacquemet (1903) and Lühe (1902) in the following terms:—
Genus Eucoccidium. Lühe (syn. Légerina Jacq.), Coccidia possessing polysporous oocysts and lacking schizogony, parasitic in Cephalopods. Two well-known species: E. eberthi (Labbé), (=Benedenia seu Klossia e. seu octopiana), parasitic in Sepia, which is tri- or tetra-zoic; and E. octopianum (Schn.), (syn. Benedenia seu Klossia o.) from Octopus, which is polyzoic, having 10 to 12 sporozoites. In both forms cysts containing megaspores and megasporozoites, and others containing microspores and microsporozoites are found, considered as representing sexual differentiation thrown back to the very earliest stages of the life-cycle.