Central capsule spherical, dark, with a thick, double-edged membrane. Nucleus central, spherical, half as large as the capsule, transparent. Protoplasm divided into numerous cuneiform radial pieces which are separated by clear intervals, and filled with very fine dark granules (darker in the distal half). The equatorial optical section exhibits around the circular clear nucleus a coronal of twenty-five such wedge-shaped pieces (mother-cells of spores?) No oil-globules in the central capsule. Jelly-like calymma one and a half times as broad as the enclosed capsule, with numerous small xanthellæ. _Dimensions._--Diameter of the capsule 0.15, of the nucleus 0.07, of the calymma 0.24. _Habitat._--North Pacific, Station 241, surface. Subgenus 2. _Actiprunum_, Haeckel, 1882. _Definition._--Central capsule ellipsoidal, with one prolonged axis. 5. _Actissa prunoides_, n. sp. _Actiprunum prunoideum_, Haeckel, 1882, Manuscript. Central capsule ellipsoidal, colourless, with a thin, simple-edged membrane. Proportion of its major axis to the minor 4 : 3. Nucleus spherical, its diameter equal to one-third of the minor axis, in its centre a large, dark, spherical nucleolus. Protoplasm clear, containing numerous small vacuoles, separated by regular distances, and on the inside of the capsule-membrane, numerous (forty to fifty) small oil-globules. Calymma (or jelly-veil) ellipsoidal, with a thin sarcode-stratum on the outside of the capsule; its diameter twice as large as that of the central capsule. _Dimensions._--Major axis of the capsule 0.16, minor 0.12; diameter of the nucleus 0.04; major axis of the calymma 0.32, minor 0.24. _Habitat._--Central Pacific, Station 274, surface. 6. _Actissa ellipsoides_, n. sp. _Actiprunum ellipsoides_, Haeckel, 1882, Manuscript. Central capsule ellipsoidal, red-coloured, with a thick, double-edged membrane. Proportion of its major axis to the minor 5 : 3. Nucleus ellipsoidal, one-third as large as the capsule, containing eight small dark nucleoli. Protoplasm dusky, filled with dark pink pigment-granules; in the {15}major axis, on both poles of the nucleus-axis, two large oil-globules, half as large as the nucleus. Calymma ellipsoidal, with numerous xanthellæ; its diameter four times as large as that of the capsule. _Dimensions._--Major axis of the capsule 0.2, minor 0.12; major axis of the nucleus 0.07, minor 0.04; major axis of the calymma 0.8, minor 0.5. _Habitat._--Mediterranean, Corfu, 1877, Haeckel, surface. Subgenus 3. _Actidiscus_, Haeckel, 1882. _Definition._--Central capsule lenticular, with one shortened axis. 7. _Actissa discoides_, n. sp. _Actidiscus discoides_, Haeckel, 1882, Manuscript.