Page:Scientific results HMS Challenger vol 18 part 1.djvu/310

102 1. Odontosphæra monodon, n. sp. (Pl. 5, fig. 5).

Shell spherical or subspherical, with very small and numerous circular pores, much smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. Between them a variable number of larger roundish apertures (mostly twelve to sixteen) irregularly scattered, one-fourth to one-fifth as broad as the shell radius. On the margin of every larger aperture a single (rarely two or three) sharp conical tooth, about as long as the diameter of the aperture, and obliquely laid over them.

Dimensions.—Diameter of the shell 0.1 to 0.13, of the pores 0.001 to 0.003, of the bars 0.01 to 0.02, of the larger apertures 0.01 to 0.02.

Habitat.—Sunda Archipelago, Station 192, surface.

2. Odontosphæra cyrtodon, n. sp. (Pl. 5, fig. 6).

Shell spherical or subspherical, with numerous roundish pores of very irregular size and distribution, mostly larger than the bars. Ten to twelve pores on the half meridian of the shell. Between them a variable number (mostly six to nine) of large roundish pores, about half as broad as the shell radius, armed on one side of the margin with one single large tooth, about as long as the diameter of the aperture, hook-like, curved, and obliquely laid over them.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.01 to 0.02, of the bars 0.003 to 0.006, of the larger apertures 0.03 to 0.04.

Habitat.—Indian Ocean, near the Cocos Islands, Rabbe, surface.

Definition.— with simple shells, armed on the outside with radial spines, forming elegant coronals around the larger pores.

The genus Chœnicosphæra is characterised by the peculiar disposition of its radial spines, which form protective coronals around the larger pores, or even around all pores of the shell.

Definition.—A coronal of spines around every pore of the shell.

1. Chœnicosphæra murrayana, n. sp. (Pl. 8, fig. 4).

Shell spherical, with large circular or roundish pores of unequal size, two to four times as broad as the bars. Ten to twelve pores in the half meridian of the shell. Margin of every pore