Page:Scientific results HMS Challenger vol 18 part 1.djvu/361

Rh

Definition.—Pores regular, all of nearly equal size and similar form; surface smooth.

1. Staurosphæra cruciata, n. sp.

Shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the quadrant. Four crossed radial spines three-sided pyramidal, as long as the diameter of the shell, as broad at the base as one pore (very similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but with only four spines).

Dimensions.—Diameter of the shell 0.12, of the pores 0.008, bars 0.002.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Staurosphæra christiana, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, three times as broad as the bars; six to eight on the quadrant. Four crossed spines six-sided pyramidal, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.13, pores 0.012, bars 0.004.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Staurosphæra johannis, n. sp.

Shell thick walled, smooth, with regular, circular pores, four times as broad as the bars; five to six on the quadrant. Four spines six-sided pyramidal, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.02, bars 0.005.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Staurosphæra pauli, n. sp.

Shell very thick walled, smooth, with regular, circular, double-edged pores, four times as broad as the bars; eight to ten on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.016, bars 0.004.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

5. Staurosphæra petri, n. sp.

Shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; twenty to twenty-two on the quadrant. Four spines conical, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.22, pores 0.006, bars 0.002.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms; also fossil in Barbados.