Page:Scientific results HMS Challenger vol 18 part 1.djvu/445

Rh 23. Haliomma spinulosum, J. Müller.

Haliomma spinulosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf. iv. fig. 6.

Cortical shell thin walled, twice as broad as the medullary shell, with irregular, polygonal pores, and very thin bars. Pores of the inner shell subregular, hexagonal, ten to twelve times as broad as the bars. Radial spines very numerous, bristle-shaped, one-sixth to one-fourth as long as the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.16, inner 0.08; outer pores 0.01 to 0.03, inner 0.02; length of the spines 0.02 to 0.03.

Habitat.—Mediterranean (Nice); Central Pacific, Station 266, surface.

24. Haliomma rhodococcus, n. sp. (Pl. 19, fig. 6).

Sethosphæra rhodococcus, Haeckel, 1879, Atlas, pl. xix. fig. 6.

Cortical shell very thin walled, little larger than the thick walled medullary shell (= 10 : 9). Pores of the outer shell very irregular, roundish, twice to six times as broad as the bars, about twenty on the radius. Pores of the inner shell twice as broad as the bars, six to eight on the radius, very regular, circular on the inner, six-lobed on the outer opening, separated by prominent hexagonal crests; in the hexagon-corners arise short conical radial spines, which at equal distances from the centre are united by the outer shell, but are prominent over its surface. (A very peculiar form; the two shells may better be regarded as inner and outer cortical shell.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.18; outer pores 0.04 to 0.012, inner 0.01; length of the spines 0.01.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil in Barbados.

25. Haliomma boreale, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with irregular, roundish pores, twice to four times as broad as the bars; eight to ten on the radius. Pores of the inner shell regular, circular, twice as broad as the bars, four to six on the radius. Radial spines very numerous, conical, nearly as long as the diameter of the shell.

Dimensions.—Diameter of the outer shell 0.24, inner 0.06; outer pores 0.008 to 0.02, bars 0.005, inner pores 0.006, bars 0.003; length of the spines 0.2.

Habitat.—Arctic Ocean, Greenland ("Alert" Expedition).

Definition.—Pores of the cortical shell irregular, of different size and form; spines not covering the entire surface, but scattered at intervals (their number smaller than that of the nodal-points in the network).