Page:Scientific results HMS Challenger vol 18 part 1.djvu/309

Rh roundish pores of very different form and size, one to four times as broad as their bars. Spines conical, irregularly diverging and curved, their hollow base perforated by several pores, not longer than the diameter of the largest pores.

Dimensions.—Diameter of the shell 0.1 to 0.2, of the pores 0.001 to 0.04; length of the spines 0.01 to 0.02.

Habitat.—Mediterranean, Messina; Canary Islands, Haeckel.

5. Acrosphæra collina, n. sp. (Pl. 8, fig. 2).

Shell quite irregular, polyhedrical, hilly, with a variable number (eight to sixteen) of large conical hill-like prominences; every cone or hill about as high as broad, perforated by the same pores as the shell, on its top bearing a larger irregular roundish pore, and on its edge one single bristle-like spine, not larger than the diameter of this pore, obliquely inserted. In the half meridian of the shell twenty to thirty irregular roundish pores of very different size, one to six times as broad as the bars. A very characteristic species, closely resembling the following Odontosphæra.

Dimensions.—Diameter of the shell 0.15 to 0.25, of the pores 0.005 to 0.02; length of the spines 0.01 to 0.02, height of the hills from which they rise 0.03 to 0.04.

Habitat.—North coast of New Guinea, Station 218, surface.

6. Acrosphæra inflata, n. sp. (Pl. 5, fig. 7).

Mazosphæra inflata, Haeckel, 1879, Atlas, ''loc. cit.''

Shell more or less irregular, polyhedral, hilly, with a variable number (six to twelve) of large pyramidal, hill-like prominences; every hill about as high as broad, on the top a strong conical, radial, or obliquely inserted spine, inflated, with three to six very large polygonal meshes, much larger than the other pores between the hills, which are also polygonal, two to six times as broad as the bars. Ten to fifteen pores on the half meridian.

Dimensions.—Diameter of the shell 0.1 to 0.14, of the largest pores 0.05, of the smallest 0.005; length of the spines 0.02 to 0.03.

Habitat.—North Atlantic, Station 64, surface.

Definition.— with simple shells, the outside of which bears single scattered spines, one single spine on the margin of each larger pore.

The genus Odontosphæra is distinguished from the foregoing Acrosphæra by the peculiar disposition of the spines, which are not scattered on the outside of the shell between the pores, but so disposed that each larger pore is protected by one single spine, obliquely placed over it.