Classification.
Aphrothoraca. Body naked. Actinophrys Ehrb. (fig. 1 (1)) (nucleate), Actinosphaerium Stein plurinucleate (fig. 2 (1)), Camptonema (plurinucleate) Schaud., Dimorpha Gruber (sometimes 2 flagellate).
I. Chlamydophora. Investment gelatinous. Astrodiscus.
II. Chalarothoraca. Body protected by an investment of spicules or fibre scattered or approximated, never fused into a continuous skeleton.
§ 1. Spicules netted or free in the protoplasm. Heterophrys Arch. (fig. 1 (3)), Raphidiophrys Arch. (fig. 1 (4)), Pinacodocystis, Hertw. and Less.
§ 2. Spicules approximated radially. Pinaciophora Greeff, Pompholyxophrys Arch., Lithocolla F. E. Schultze, Elaeorhanis Greeff (in the two foregoing genera the spicules represented by sand granules), Acanthocystis Carter (fig. 1 (5)), Pinacocystis (?) Hertw. and Less, Myriophrys Penard. (Astrodisculus).
III. Desmothoraca. § 1 attached by a stalk. Clathrulina Cienk. (fig. 1 (2, 7)), Hedriocystis, Hertw. and Less.
§ 2. Free Elaster, Grimin, Choanocystis.
Literature.—The most important English original papers on this group are those by W. Archer, “On some Freshwater Rhizopoda, new, or little known,” Quarterly Journal of Microscopic Science, N.S. ix.-xi. (1869-1871), and “Résumé of Recent Contributions to the Knowledge of Freshwater Rhizopods,” ibid. xvi., xvii. (1876-1877). See also R. Hertwig and Lesser, “Über Rhizopoda und denselben nahestehenden Organismen,” in Archiv für mikroscopische Anatomie, x. (1874), p. 35; R. Schaudinn, “Heliozoa” in Tierreich (1896); E. Penard, Les Héliozoaires d’eau douce (1904); the two last named contain full bibliographies.
(M. Ha.)