Page:Scientific results HMS Challenger vol 18 part 1.djvu/430

222 3. Conosphæra plagioconus, n. sp. (Pl. 12, fig. 4).

Pores of the shell irregular, polygonal, twice to five times as broad as the bars; twenty to twenty-four on the radius. Conical spines about eighty, irregularly formed and scattered, with oblique (not radial) axes; about as high as broad, with eight to twelve pores in the wall.

Dimensions.—Diameter of the shell 0.25, pores 0.005 to 0.015, bars 0.003; length of the spines 0.02, basal breadth 0.02.

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

Definition.— with one simple lattice-sphere, covered with simple radial spines; the pores between them prolonged into hollow, conical, or cylindrical tubuli.

The genus Coscinomma exhibits among the Astrosphærida the same peculiar formation that distinguishes Ethmosphæra and Sethosphæra among the Liosphærida; each pore of the simple shell is prolonged into a short conical or cylindrical tubulus, as a rule either on the outside or on the inside of the shell, but sometimes on both sides.

Definition.—Pores prolonged into short tubes both on the inside as well as the outside of the shell.

1. Coscinomma amphisiphon, Haeckel (Pl. 26, figs. 1, 1a, 1b).

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the inside as well as on the outside of the shell into a short truncated conical tube; fifteen to eighteen pores on the radius. In each hexagon-corner arises a bristle-shaped radial spine, half as long as the radius.

Dimensions.—Diameter of the shell 0.22, pores 0.01, bars 0.005; length of the spines 0.1.

Habitat.—Central Pacific, Station 271, surface.

Definition.—Pores prolonged into external tubes on the outside of the shell.

2. Coscinomma ectosiphon, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the outside of the shell into a short truncated conical tube; ten to twelve pores on the radius. In each