Central capsule lenticular, red-coloured, about twice as broad as high, with a thick, double-edged membrane. Nucleus spherical, one-third as broad as the capsule, with one single, large central nucleolus. Protoplasm dusky, filled with scarlet pigment; granules and small oil-globules between them. Calymma lenticular, three times as broad as the capsule. _Dimensions._--Major axis of the capsule 0.16, minor 0.08; diameter of the nucleus 0.05; breadth of the calymma 0.5. _Habitat._--North Pacific, Station 236, surface. 8. _Actissa lenticularis_, n. sp. Central capsule lenticular, flattened, about three times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-third as large as the capsule, with ten small dark nucleoli. Protoplasm transparent, colourless, filled with small vacuoles at regular distances; on the inside of the membrane in the circular periphery of the lens twenty dark oil-globules. Calymma lenticular, twice as broad as the capsule. _Dimensions._--Major axis of the capsule 0.15, minor 0.05; breadth of the nucleus 0.05, height 0.02; breadth of the calymma 0.03. _Habitat._--East Pacific, Station 272, surface. 9. _Actissa phacoides_, n. sp. _Actidiscus phacoides_, Haeckel, 1882, Manuscript. Central capsule lenticular, strongly flattened, about four times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-fourth as broad as the capsule, with numerous (twenty or more) small nucleoli. Protoplasm filled with dark pigment-granules; on the inside of the membrane in the circular periphery of the lens thirty-two dark oil-globules. Calymma lenticular, three times as broad as the capsule. {16}_Dimensions._--Major axis of the capsule 0.2, minor 0.05; breadth of the nucleus 0.05, height 0.015; breadth of the calymma 0.6. _Habitat._--Tropical Atlantic, Station 347, surface. Subgenus 4. _Actilarcus_, Haeckel. _Definition._--Central capsule lentelliptical, with three different axes. 10. _Actissa larcoides_, n. sp. Central capsule lentelliptical; with three different axes, bearing the proportion 4 : 3 : 2. Nucleus spherical; its diameter equal to the shortest radius of the capsule. No nucleoli visible. Protoplasm transparent, with small vacuoles; on the inside of the thin capsule-membrane numerous (fifty to sixty) small oil-globules, regularly disposed. Calymma lentelliptical, twice as large as the central capsule. _Dimensions._--Major axis or length of the capsule 0.2, middle axis or breadth 0.15, minor axis or height 0.1; diameter of the nucleus 0.05, of the calymma 0.3-0.4. _Habitat._--Central Pacific, Station 266, surface. Genus 2. _Thalassolampe_,[9] Haeckel, 1862, Monogr. d. Radiol., p. 253. _Definition._--#Thalassicollida# without extracapsular alveoles, but with large roundish or globular alveoles within the central capsule, with a simple spherical, not branched nucleus in the centre.