1834. Meyen (L. N. 1) describes 2 genera and species of Collodaria:—Sphærozoum fuscum and Physematium atlanticum.

1838. Ehrenberg (L. N. 2) founds the family Polycystina upon 3 fossil genera (with 6 species):—Lithocampe, Cornutella, Haliomma.

1847. Ehrenberg (L. N. 4) publishes his preliminary communications regarding the fossil Polycystina of Barbados and distinguishes 282 species, distributed in 44 genera and 7 families. In the tabular view of the genera he distinguishes two orders:—I. Solitaria—(1) Halicalyptrina, (2) Lithochytrina, (3) Eucyrtidina; and II. Composita—(4) Spyridina, (5) Calodictya, (6) Haliommatina, (7) Lithocyclidina (compare L. N. 16, pp. 214-219).

1851. Huxley (L. N. 5) gives the first accurate account of living Radiolaria, and describes 2 species of the genus Thalassicolla (nucleata and punctata); under the latter are included 4 genera of Sphærozoea:—Collozoum, Sphærozoum, Collosphæra, Siphonosphæra (compare L. N. 16, pp. 12-14).

1854. Ehrenberg (L. N. 6) publishes in his Mikrogeologie, figures of seventy-two species of fossil Polycystina (without descriptions).

1855. Johannes Müller (L. N. 8, p. 248) describes the first Acanthometra, and elucidates its affinity to Huxley's Thalassicolla and Ehrenberg's Polycystina.

1858. Johannes Müller (L. N. 12) establishes the new group Radiolaria as a special order of the Rhizopoda, and includes in it the Thalassicolla, Polycystina, and Acanthometra as closely related families. He opposes these radiate Rhizopoda to the Polythalamia, and describes 50 species observed by him living in the Mediterranean, these he arranges in 20 genera, of which 10 are new. The figures are contained in eleven plates (see L. N. 16, pp. 22-24).

1858. Claparède (L. N. 14) describes the first Plectoidean (Plagiacantha arachnoides) and two species of Acanthometra, which he had observed living in Norway (see L. N. 16, p. 18).

1860. Ehrenberg (L. N. 4) gives a short diagnosis of 22 new genera of Polycystina, based on the investigation of numerous deep-sea species brought up by Brooke from the depths of the Pacific Ocean. The number of his genera is thus increased to 66 (compare L. N. 16, pp. 10, 11).

1862. Ernst Haeckel (L. N. 16) embraces in his Monograph of the Radiolaria all the species hitherto known either by figures or descriptions, and arranges them in 15 families and 113 genera; of which latter 46 are new. The number of new species observed living amounts to 144. In a "survey of the Radiolarian fauna of Messina" (p. 565) he records 72 genera and 169 species. Most of these are figured in the accompanying atlas of thirty-five plates.

1862. Bury (L. N. 17) gives in an atlas of twenty-five plates, photographed from drawings, the figures of numerous fossil Polycystina of Barbados (without descriptions), of which many are new species overlooked by Ehrenberg (compare § 242, above).

1872. Ehrenberg (L. N. 24) gives a list of names (without description) of all the Polycystina observed by him from the bottom of the sea, 279 species, of which 127 are figured on twelve plates.

1875. Ehrenberg (L. N. 25) gives a list of names of all the fossil Polycystina observed by him (from Barbados, the Nicobar Islands and Sicily), 326 species, of which 282 are figured (compare § 242 above). In a new "Systematic Survey of the Genera" the number of these is given as 63. The 7 families are the same as given in 1847 (see above), as also the two orders (Nassellaria = Solitaria, Spumellaria = Composita).

1876. Zittel (L. N. 29) describes the first fossil Radiolaria from the chalk (6 species) and establishes the new Cyrtoid genus Dictyomitra.

1876. John Murray (L. N. 27) establishes the new family Challengerida, and figures 6 new generic types of Phæodaria.

1879. Richard Hertwig (L. N. 33) first describes the fundamental differences in the structure of the central capsule, and in accordance with them divides the Radiolaria into six orders:—(1) Thalassicollea, (2) Sphærozoea, (3) Peripylea, (4) Acanthometrea, (5) Monopylea, (6) Tripylea (p. 133). These are subdivided into 18 families, and their phylogenetic affinities discussed (p. 137). On the ten plates, several new species from Messina are figured, among them the types of several new genera (Cystidium, Cœlacantha, Echinosphæra) (compare § 252).

1879. Ernst Haeckel (L. N. 34) founds the order Phæodaria as a "new group of marine siliceous Rhizopods," and distinguishes in it 4 suborders, 10 families and 38 genera.

1880. Emil Stöhr (L. N. 35) describes the Miocene "Radiolarian fauna of the tripoli from Grotte in Sicily," 118 species, of which 78 are new; among them is the new genus Ommatodiscus, the type of a new family, Ommatodiscida. The new species are figured on seven plates.

1880. Dante Pantanelli (L. N. 36) describes 30 species of fossil Polycystina from the jaspers of Tuscany, which he regarded as Eocene, but which were probably of Jurassic origin (compare § 243, note B, above).

1881. Ernst Haeckel (L. N. 37) publishes a "Sketch of a classification of the Radiolaria on the basis of the study of the Challenger Collection," and distinguishes in his "conspectus ordinum" (p. 421) 2 subclasses and 7 orders, and in the "prodromus systematis Radiolarium" (pp. 423-472) 24 families with 630 genera, among which are more than 2000 new species.

1882. Bütschli (L. N. 40) on the basis of studies of the fossil Monopylea of Barbados, investigates the "mutual relations of the Acanthodesmida, Zygocyrtida and Cyrtida," and gives a critical revision of the genera of these "Cricoidea;" a number of new species are described and figured (Tafs. xxxii., xxxiii.), and some new genera of Stichocyrtida established (Lithostrobus, Lithomitra, &c.).

1882. Dunikowski (L. N. 44) describes 18 new fossil Polycystina from the lower lias of the Salzburg Alps, among them the types of 3 new genera (Ellipsoxiphus, Triactinosphæra, and Spongocyrtis).

1883. Ernst Haeckel (L. N. 46) revises the 4 orders and 32 families of Radiolaria, and gives more accurate definitions of them, as well as of the 2 subclasses (I. Holotrypasta = Acantharia and Spumellaria; II. Merotrypasta = Nassellaria and Phæodaria).

1885. D. Rüst (L. N. 51) describes 234 new species of fossil Radiolaria from the Jura, and illustrates them by twenty plates. Among them are 103 Spumellaria, 130 Nassellaria, and 1 Phæodaria; these are contained in 35 genera, of which 20 belong to the Porulosa, and 15 to the Osculosa.