Dimensions.—Diameter of the outer shell 0.12, pores 0.012, bars 0.003; inner shell 0.04; length of the polar spines 0.04, thickness 0.013.
Habitat.—Indian Ocean, Cocos Islands, Rabbe.
10. Stylosphæra hispida, Ehrenberg, 1854.
Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, spiny, with regular, circular pores of the same breadth as the bars; ten to fifteen on the half equator. Polar spines three-sided prismatic, pointed, about as long as the axis of the outer sphere, nearly as broad at the base as the inner sphere. (Compare Sphærostylus hispidus; also Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1874, p. 259.)
Dimensions.—Diameter of the outer shell 0.1 to 0.12, pores and bars 0.004; inner shell 0.04; length of the polar spines 0.1 to 0.15, basal breadth 0.03.
Habitat.—Fossil in the Tertiary rocks of Sicily, Barbados, Nicobars, &c.
11. Stylosphæra liostylus, Ehrenberg, 1875.
Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, thorny, with regular, circular pores, three times as broad as the bars; eight to ten on the half equator. Polar spines conical, once and a half to twice as long as the axis of the outer sphere, half as broad at the base as its radius. (This species, common in the Barbados rocks, is different from Sphærostylus liostylus, loc. cit., fig. 2, which Ehrenberg believed identical.)
Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.0035; inner shell 0.03; length of the polar spines 0.14 to 0.18, basal breadth 0.02.
Habitat.—Fossil in the Barbados rocks; living in the depths of the North Atlantic, Gulf Stream, Florida.
Subgenus 3. Stylosphærissa, Haeckel.
Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without thorns or spines.
12. Stylosphæra nana, n. sp. (Pl. 16, figs. 12, 13).
Radial proportion of the two spheres = 2 : 1. Cortical shell thick walled, somewhat irregular, smooth, with irregular, roundish pores, one to three times as broad as the bars; eight to ten on the half equator. Polar spines three-sided pyramidal, scarcely as long as the axis of the outer sphere, and nearly as broad at the base as its radius. (A very variable and irregular form.)
Dimensions.—Diameter of the outer shell 0.07 to 0.09, pores 0.003 to 0.009, bars 0.003; inner shell 0.03 to 0.04; length of the polar spines 0.04 to 0.07, basal breadth 0.03.
Habitat.—North Pacific, Stations 241 to 253, surface.
