Two organisms, Microcometes paludosa and Wagnerella borealis, are regarded by some authorities as Heliozoans. The former was found under freshwater gelatinous algae in North and South Russia by Cienkowski. It has a globular membranous capsule pierced in a few places by round holes. The body is smaller than its capsule; it has an excentric nucleus, 2-3 peripheral contractile vacuoles; and it emits through the openings of its capsule one or more long slightly branched pseudopodia. It feeds on Algae which are either drawn into the capsule or have their cell-contents sucked out by the pseudopodia. Binary fission was seen, both parts quitting the capsule; also encystation within a tough cyst, the capsule at the same time becoming spinulose. (Cienkowski, A. M. A. xii. 1876, pp. 46-7, cf. Allman, J. L. S. xiii. p. 302). Wagnerella borealis from the White Sea was described by its discoverer, Merejkowski, as a sponge. It occurs also in the Mediterranean and was found by Mayer to be a Protozoon and probably a Heliozoon, a view to which Merejkowski has given his adhesion. It is attached by a conical base prolonged upwards into a cylindrical peduncle supporting a globular body. The peduncle may attain i.i mm. in length; the head .18 mm. in diameter.

A thin membrane covers both head and base and contains curved siliceous spicules. There are also long slender siliceous spicules radiating from the head. The nucleus is in the base, but at times wanders thence into the head and divides into eight nuclei, which are destined one for each of the reproductive buds. There are pseudopodia. (Merejkowski, Mem. Imp. Acad. St. Petersburg, (7), xxvi. 1879, No. 7, p. 15; A. N. H. (5), i. 1878; viii. 1881; Mayer, Z. A. ii. 1879; iv. 1881).

The Zooteira religata of Strethill Wright is probably a Heliozoon. It has an ecto- and endo-sarc, very numerous pseudopodia, a contractile peduncle, and a basal gelatinous tube into which the animal can be withdrawn. Q. J. M. ii. 1862, p. 217.

Butschli thinks that R. Hertwig's Sticholonche zandea may possibly belong to the Heliozoa Chalarothoraca. By Fol it is made the type of a new order (? class) Taxopoda. It is marine, and was found by Hertwig at Messina. In outline it is bean-shaped and about .15 mm. in length. It contains a bean-shaped capsule or nucleus triangular in cross section. The capsular membrane is tough, covered by minute rods according to Fol, or to Hertwig by perforated elevations which are prolonged into tubes; its contents are homogeneous with one large or several small vacuoles. The body is clothed by a membranous investment composed of separate pieces. Its outline is not even but elevated into prominences. Each of the latter carries a circlet of about twenty hollow chitinous spines grouped round a larger spine. Pseudopodia, in the proper sense of the word, are absent; in place of them there are four rows of scarcely contractile 'arms' which contain, at least at their bases, a special axial substance (Fol). In locomotion the 'arms' were observed by Hertwig to be simultaneously applied to a surface, and to move the body onwards with a jerk. The protoplasm is granular or homogeneous with, in most instances, clear globules of refrangibility identical with its own (Fol). There are no contractile vacuoles.

Fol observed near the concave side of the nucleus globules, a few in small individuals, many in large. The globules divided into two groups which came to lie one on each side of the animal. In some instances one or both these heaps was replaced by a large body with a figure of 8 cavity. Later on, it contained a spirally constricted body which was set free as a multinucleate holotrichous organism, considered by Fol not to be a parasitic Infusorian but a spermatophore, the small globules of other specimens being ova (!). He thinks that the peculiar bodies seen by Hertwig in Acanthometrids are of analogous nature and to be considered as embryoes. R. Hertwig, J. Z. xi. 1877, pp. 325-331; Id. Organismus der Radiolarien, Dk. Jen. Ges. ii. 1880, p. 176; Fol, Mem. Inst. Nat. GeneVois, xv. 1883.

The Heliozoa are classified as follows: 1. Aphrothoraca: no skeleton present; Actinophrys Sol, Actinosphaerium Eichhornii, Actinolophus, Haeckelina; Lithocolla, Elaeorhanis, Chondropus.

2. Chlamydophora, with a continuous soft (? gelatinous) skeleton: Heterophrys, Sphaerastrum, Astrodisculus, Astrococcus.

3. Chalarothoraca: a loose siliceous skeleton: Pompholyxophrys (= Hyalo-lampe), Raphidiophrys, Pinacocystis, Pinaciophora, Acanthocystis.

4. Desmothoraca: skeleton, a siliceous shell, more or less globular, pierced by apertures; free Orbulinella, Elaster; fixed and pedunculate, Clathrulina, Hedrio-cystis.

Butschli, Bronn's Klass. und Ordn. des Thierreichs, i. Protozoa, pp. 261-331; Archer, Re'sumd, Q. J. M. xvi. 1876; xvii. 1877, and Allman, J. L. S. xiii. 1878, pp. 284-305; Leidy, 'Freshwater Rhizopoda of N. America,' U. S. Geological Survey of the Territories, xii. 1879, pp. 233-76 (except pp. 253-8).

Actinosphaerium, Brandt, Inaug. diss., Halle, 1877. Haeckelina, Merejkowski, A. M. A. xvi. 1879, p. 211. Elaeorhanis, Greeff. A. M. A. xi. 1875, p. 23. Acanthocystis, R. Hertwig, J. Z. xi. 1877, p. 331. Acanthocystis Italica, Raphidiophrys arenosa, Gruber, Nova Acta, xlvi. 1884, pp. 507-8. R. socialis, Leidy, A. N. H. (5), xii. 1883, p. 209. Orbulinella, Entz, Naturhistor. Hefte des Nat. Mus. in Buda-Pesth, pt. I, 1877. Elaster, Grimm, A. M. A. viii. 1872, p. 531.

Axial filaments and movements of Actinosphaerium, Brandt, SB. Ges. Natf. Freunde zu Berlin, 1878, p. 171; structure of protoplasm of same, Butschli, M. J. xi. 1886, pp. 91-2; digestion in same, and Amoeba, Greenwood, Journal of Physiology, vii. 1886; mode of catching prey, Maupas, A. Z. Expt. ix. 1881, pp. 357-8. Chlorophyl bodies,'see note 1, p. 868 ante. Nucleus, Gruber, Z. W. Z. xl. 1884, pp. 131-4; cf. Id. and Brandt, Biol. Centralblatt. iii. 1883-4; fission of nucleus in Actinosphaerium, R. Hertwig, J. Z. xvii. 1884.

Fusion of Actinophrys Sol, Gruber, Z. W. Z. xxxviii. 1883, p. 62-8; cf. Cox, Amer. Monthly Micr. Journal, ii. 1882; encystation of do., Cienkowski, A. M. A. i. 1865, p. 227; and fusion, Lieberkuhn, Arch. f. Anat. und Physiol., 1856, pp. 505-7. Reproduction of Actinosphaerium, Brandt, SB. Ges. Natf. Freunde zu Berlin, 1877, p. 73; cf. note 2, p. 870 ante-, of Clathrulina, Foulke, A. N. H. (5), xiv. 1884. Budding in Acanthocystis, R. Hertwig, J. Z. xi. 1877, pp. 337-40; Korotneff, A. Z. Expt. viii. 1879-80, p. 481. Spores and amoebiform young, see note 2, p. 870 ante.