1. Coscinomma amphisiphon, Haeckel (Pl. [26], figs. 1, 1a, 1b).
Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the inside as well as on the outside of the shell into a short truncated conical tube; fifteen to eighteen pores on the radius. In each hexagon-corner arises a bristle-shaped radial spine, half as long as the radius.
Dimensions.—Diameter of the shell 0.22, pores 0.01, bars 0.005; length of the spines 0.1.
Habitat.—Central Pacific, Station 271, surface.
Subgenus 2. Coscinommidium, Haeckel.
Definition.—Pores prolonged into external tubes on the outside of the shell.
2. Coscinomma ectosiphon, n. sp.
Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the outside of the shell into a short truncated conical tube; ten to twelve pores on the radius. In each hexagon-corner arises a short bristle-shaped spine, twice as long as the tube, one-third as long as the radius. (Very similar to Ethmosphæra conulosa, Pl. [12], fig. 5, but differs in the possession of radial spines.)
Dimensions.—Diameter of the shell 0.2, pores 0.012, bars 0.006; length of the spines 0.04, of the tubes 0.02.
Habitat.—North Pacific, Station 253, surface.