Page:Scientific results HMS Challenger vol 18 part 1.djvu/366

158 one mesh; one of the spines longer than the shell diameter, the opposite spine nearly as long as the shell radius; both lateral spines scarcely one-third as long.

Dimensions.—Diameter of the shell 0.1, pores 0.01, bars 0.005; length of the major spine 0.14, of the opposite 0.04, of both lateral spines 0.012.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Stylostaurus gladiatus, n. sp.

Shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; nine to ten on the quadrant. Spines three-sided prismatic, as broad at the base as one mesh; one of the spines longer than the shell diameter, and much larger than the other three, which are nearly equal (half as long as the radius).

Dimensions.—Diameter of the shell 0.2, pores 0.015, bars 0.005; length of the major spine 0.25, of the three others 0.005.

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

Definition.— with two concentric spherical lattice-shells.

Definition.— with two concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurolonche may be derived either from Staurosphæra by the duplication of the lattice-sphere, or from Carposphæra by the production of four crossed radial spines, lying in one meridional plane, or from Hexalonche by the reduction of two opposite spines.

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

1. Staurolonche hexagona, n. sp.

Haliomma hexagonum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvb., Bd. iv. fig. 17.

Haliomma hexagonum, Haeckel, 1862, Monogr. d. Radiol., p. 434.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, hexagonal pores, four times as broad as the bars; seven to eight on the quadrant. Four spines three-sided pyramidal, somewhat longer than the radius, as broad at the base as one mesh.