Dimensions.—Diameter of the shell 0.12, pores 0.012, bars 0.003; length of the spines 0.06, basal breadth 0.012.
Habitat.—Indian Ocean, Madagascar, surface, Rabbe.
8. Hexastylus pittaci, n. sp.
Shell thin walled, smooth. Pores regular, circular, ten to twelve times as broad as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the radius, as broad as one pore.
Dimensions.—Diameter of the shell 0.12, pores 0.02, bars 0.002; length of the spines 0.06, basal breadth 0.02.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
9. Hexastylus maximus, n. sp.
Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars; twelve to sixteen on the radius. Six spines six-sided pyramidal, half as long as the radius, three times as broad as one pore.
Dimensions.—Diameter of the shell 0.3, pores 0.01, bars 0.005; length of the spines 0.08, basal breadth 0.03.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
10. Hexastylus periandri, n. sp.
Shell thick walled, smooth. Pores regular, circular, double-edged, four times as broad as the bars; six to seven on the radius. Six spines conical, as long as the radius, twice as broad as one pore.
Dimensions.—Diameter of the shell 0.2, pores 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.025.
Habitat.—Tropical Atlantic, Station 335, depth 1425 fathoms.
Subgenus 2. Hexastylettus, Haeckel.
Definition.—Pores regular or subregular, of nearly equal size and form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped radial by-spines.
11. Hexastylus solonis, n. sp. (Pl. 21, fig. 11).
Shell thick walled, covered with numerous bristle-shaped radial spines (one-third to one-half as long as the six main spines, arising from the lattice-knots). Pores regular, circular, enclosed by prominent, hexagonal frames, four to six times as broad as the bars; seven to eight on the radius.
