Page:Scientific results HMS Challenger vol 18 part 1.djvu/290

82 12. Thecosphæra dodecactis, n. sp.

Cortical shell thin walled, smooth, with large irregular roundish pores, two to eight times as broad as the bars. Both medullary shells with regular circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 5; they are connected by twelve regularly disposed stout radial beams.

Dimensions.—Diameter of the outer shell 0.2, middle 0.08, inner 0.04; cortical pores 0.004 to 0.016, bars 0.002.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

13. Thecosphæra icosactis, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to four times as broad as the bars. Both medullary shells with similar but smaller pores. Radial proportion of the three spheres = 1 : 3 : 8; they are connected by twenty thin radial beams.

Dimensions.—Diameter of the outer shell 0.32, middle 0.12, inner 0.04; cortical pores 0.005 to 0.012, bars 0.003.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

14. Thecosphæra maxima, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to six times as broad as the bars. Both medullary shells with similar, but smaller, pores. Radial proportion of the three spheres = 1 : 3 : 9; they are connected by numerous (forty to sixty or more) thin radial beams.

Dimensions.—Diameter of the outer shell 0.45, middle 0.15, inner 0.05; cortical pores 0.008 to 0.024, bars 0.004.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Definition.— with one medullary (intracapsular) shell and two cortical (extracapsular) shells.

The genus Rhodosphæra differs from the preceding Thecosphæra in the same manner in which, among the Dyosphærida, Liosphæra differs from Carposphæra. The cortical shell is double, composed of two not far distant shells, lying outside the central capsule. The distance between the shells is much smaller than the radius of the inner shell. This is connected by radial beams (piercing the central capsule) with the small central medullary shell.

Definition.—Pores of both cortical shells regular, in each shell all of nearly equal size and form.