5. Acanthosphæra dentata, Haeckel.
Shell thin walled, eight to ten times as broad as one pore. Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial spines arising from all the nodal-points of the network, three-sided prismatic, with dentated or serrated edges, longer than the shell diameter.
Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.003.
Habitat.—Mediterranean (Messina), surface.
6. Acanthosphæra acufera, Haeckel.
Shell thin walled, eight to ten times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, about as long as the diameter of the shell.
Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.08.
Habitat.—Mediterranean (Messina); North Atlantic, Station 354, surface.
7. Acanthosphæra castanea, n. sp. (Pl. 26, fig. 3).
Shell thick walled, thirty times as broad as one mesh. Pores regular, circular, nearly of the same breadth as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, scarcely half as long as the radius of the shell.
Dimensions.—Diameter of the shell 0.15, pores and bars 0.005; length of the spines 0.03.
Habitat.—North Pacific, Station 244, surface.
8. Acanthosphæra flosculenta, n. sp.
Shell thick walled, thirteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars, with an elegant six-lobed frame (Pl. 28, fig. 1b). In the intervals between the six lobes of each mesh arise six conical radial spines (half as long as the radius), six around each pore. (Differs from the similar Haliomma flosculentum, Pl. 28, fig. 1, in the absence of an enclosed medullary shell and the stronger development of the spines.)
Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.003; length of the spines 0.03.
Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.
Subgenus 2. Rhaphidocapsa, Haeckel.
Definition.—Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines scattered at some distance apart, not at all the nodal-points.
