4. Amphisphæra apollo, n. sp.
Radial proportion of the three spheres = 3 : 1.5 : 1. Cortical shell thick walled, spiny, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twenty to twenty-two on the half equator. In each hexagon-corner (between three pores) a bristle-like radial spine. Polar spines cylindrical, with conical apex; one to one and a half times as long as the axis of the outer shell, as broad as three pores at the base. (Resembles closely Xiphosphæra pallas, Pl. [14], fig. 4, but differs in the presence of two medullary shells and the absence of the fine denticulations on the hexagonal crests.)
Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.04; pores and bars of the cortical shell 0.006; length of the polar spines 0.15, breadth 0.02.
Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.
5. Amphisphæra mercurius, n. sp.
Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, spiny, with regular, circular pores, twice as broad as the bars; fifteen to eighteen on the half equator; between them short bristle-like radial spines. Polar spines three-sided pyramidal, about as long as the radius of the outer shell, one-third as broad at the base.
Dimensions.—Diameter of the outer shell 0.15, middle 0.09, inner 0.05; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.09, basal breadth 0.03.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
Subgenus 3. Amphisphærissa, Haeckel.
Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns.