Page:Scientific results HMS Challenger vol 18 part 2.djvu/819

Rh corona of twelve to sixteen pores surrounded by a circle of numerous, curved, longer bristles. Mouth cruciform, with four triangular, convergent teeth.

Dimensions.—Diameter of the shell 0.55, length of the spines 0.4.

Habitat.—South Pacific, Station 289, depth 2550 fathoms.

2. Circoporus hexastylus, n. sp. (Pl. 117, fig. 4).

Shell regularly octahedral, with eight plane, congruent, triangular faces, which are covered with a very delicate network of small, regular, hexagonal plates. Six radial spines as long as the radius of the shell, four-sided pyramidal, simple, in the basal half covered with numerous curved bristles. Around the base of each spine a corona of four equal pores, surrounded by a circle of twelve short teeth. Apex with four crossed, curved branches (like those of Circospathis tetrodon). Mouth cruciform, with four smooth teeth.

Dimensions.—Diameter of the shell 0.24, length of the spines 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Circoporus characeus, n. sp.

Shell spherical, covered with a delicate network of irregular polygonal plates. Six radial spines longer than the diameter of the shell, cylindrical, covered with numerous curved bristles, each with eight pores at the base surrounded by a circle of long bristles. Apex of each spine with a trident or fuscina, similar to that of the following species. Similar to an antheridium of Chara.

Dimensions.—Diameter of the shell 0.32, length of the spines 0.4.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

4. Circoporus sexfuscinus, n. sp. (Pl. 115, figs. 1-3).

Shell subregular, octahedral, with eight triangular, concave, somewhat unequal faces, which are covered with an extremely delicate network of small square dimples, and furrowed by radial crests arising from the bases of the spines (fig. 2). Six radial spines about as long as the diameter of the shell, four-sided, prismatic, with rounded edges; each in the basal half with a verticil of four crossed, curved bristles (fig. 1), sometimes with two verticils (fig. 2); on the distal apex inflated, armed with a trident or fuscina. Around the base of each spine four crossed elliptical pores. Mouth cruciform, with four small teeth (fig. 1).

Dimensions.—Diameter of the shell 0.2 to 0.25, length of the spines 0.2 to 0.25.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

5. Circoporus octahedrus, n. sp. (Pl. 117, fig. 6).

Shell regularly octahedral, with eight plane, or slightly convex, congruent, triangular faces, which are covered with very small, regular, triangular plates (like those of Polypetta tabulata, Pl. 116, fig. 2). Six stout radial spines, about as long as the diameter of the shell, four-sided prismatic,