Page:Scientific results HMS Challenger vol 18 part 1.djvu/364

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Definition.—Pores irregular, of different size or form; surface covered with by-spines or accessory thorns.

14. Staurosphæra bartholomæi, n. sp.

Shell thin walled, with irregular, polygonal pores, three times as broad as the bars; six to eight on the quadrant; surface covered with short bristle-shaped by-spines. Four main spines three-sided pyramidal, twice as long as the radius.

Dimensions.—Diameter of the shell 0.14, pores 0.008 to 0.016, bars 0.003 to 0.005.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

15. Staurosphæra thaddæi, n. sp.

Shell thick walled, with irregular, roundish, polygonally framed pores, twice to three times as broad as the bars; five to seven on the quadrant; surface covered with bristle-shaped spines, half as long as the radius. Four main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 006 to 0.012, bars 0.004.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

16. Staurosphæra matthæi, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the quadrant; surface covered with short conical thorns or by-spines. Four main spines conical, as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores 0.004 to 0.01, bars 0.002.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Definition.— with one single lattice-sphere and four crossed spines which are arranged in opposite pairs, one pair opposite being larger than the other.

The genus Staurostylus has been developed from Staurosphæra by differentiation of the four crossed spines in pairs; two opposite spines growing much more strongly than the other two.

1. Staurostylus græcus, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the quadrant. Spines three-sided prismatic, pointed, as broad as