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. {clxxxvii}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.