Dimensions.—Diameter of the outer shell 0.2, pores 0.01, bars 0.003; diameter of the inner shell 0.06; length of the polar spines 0.2, basal breadth 0.02.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
2. Stylosphæra urania, n. sp.
Radial proportion of the two shells = 4 : 1. Cortical shell thin walled, smooth; pores regular, circular, hexagonally framed, twice as broad as the bars; ten on the half equator. Polar spines conical, as long as the radius of the outer shell.
Dimensions.—Diameter of the cortical shell 0.24, pores 0.012, bars 0.006; medullary shell 0.06; length of the polar spines 0.12, basal breadth 0.024.
Habitat.—South Pacific, Station 285, depth 2375 fathoms.
3. Stylosphæra calliope, n. sp. (Pl. [16], fig. 6).
Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars. Each pore on its outer opening with eight regular lobules, flower-like. Nine to ten pores on the half equator. Polar spines three-sided pyramidal, with three strong prominent edges, about as long as the axis, as broad as one pore. (Sometimes, as in the figured specimen, one spine is smaller than the other; this variety, otherwise identical, may be called Sphærostylus calliope.)
Dimensions.—Diameter of the outer shell 0.12, pores 0.015, bars 0.005; inner shell 0.04; length of the polar spine 0.08 to 0.12, breadth 0.02.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.