Page:Scientific results HMS Challenger vol 18 part 1.djvu/293

Rh 3. Cromyosphæra bigemina, n. sp.

Radial proportion of the four spheres = 1 : 2 : 7 : 8. Outer cortical shell smooth, with regular hexagonal pores and very thin bars; inner cortical shell with the same number of exactly corresponding, regular circular pores. Both medullary shells with regular circular pores of the same breadth as the bars. (Somewhat similar to Hexacromyon elegans, Pl. 24, fig. 9, also with six inner radial beams, but without external radial spines.)

Dimensions.—Diameter of the four spheres—(A) 0.2, (B) 0.17, (C) 0.05, (D) 0.025.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Cromyosphæra cepa, n. sp.

Radial proportion of the four spheres = 1 : 2 : 4 : 5. All four shells of the same structure, thick-walled, with regular circular pores, two to four times as broad as the bars; the size of the pores increases gradually from the inner to the outer shell. Surface thorny. Distance between the second and third shells twice as great as that between the others.

Dimensions.—Diameter of the four spheres—(A) 0.125, (B) 0.1, (C) 0.05, (D) 0.025.

Habitat.—Fossil in Barbados.

5. Cromyosphæra scorodonium, n. sp.

Radial proportion of the four spheres = 1 : 2 : 3 : 4. All four shells of the same structure, thin-walled, with irregular roundish pores, two to four times as broad as the bars; the size of the pores increasing gradually from the inner to the outer shell. Surface smooth. Distance between each two shells equal to the diameter of the innermost.

Dimensions.—Diameter of the four spheres—(A) 0.12, (B) 0.09, (C) 0.06, (D) 0.03.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

6. Cromyosphæra antarctica, n. sp..

Radial proportion of the four spheres = 1 : 2 : 5 : 7. Both cortical shells with irregular polygonal roundish pores; the outermost with thinner bars and rough surface, the inner with thicker bars. Both medullary shells with irregular roundish pores.

Dimensions.—Diameter of the four spheres—(A) 0.18, (B) 0.12, (C) 0.05, (D) 0.025.

Habitat.—Antarctic Ocean; in very large number, together with Rhizosphæra antarctica, in the diatomaceous ooze of Station 157 (3rd March 1874); depth 1950 fathoms.

Definition.— with numerous (five or more) concentric spherical latticed shells, united by radial beams.