16. Sethophormis dodecaster, n. sp. (Pl. [56], fig. 12).
Cephalis small, flatly cap-shaped, with irregular, small, roundish pores. Thorax flatly conical, nearly of the same shape as in the preceding species, but only with twelve prominent ribs; four primary or perradial ribs (as prolongations of the four crossed cortinar bars), and eight adradial ribs interpolated between the former, and arising at some distance from the collar ring. Peristome with twelve prominent pointed lobes (supported by the distal ends of the twelve ribs), and with twelve semicircular bosoms between them. (The specimen figured is young and not fully developed.)
Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.3 broad.
Habitat.—South Pacific, Station 298, depth 2225 fathoms.
17. Sethophormis umbrella, n. sp. (Pl. [70], figs. 4, 5).
Cephalis large, flatly cap-shaped, with irregular, small polygonal meshes. Thorax flat, umbrella-shaped, with subregular, hexagonal meshes, and sixteen strong radial ribs. Four of these are perradial, and centrifugal prolongations of the four crossed collar beams; four others are interradial, and arise, alternating with the former, directly from the horizontal collar ring; eight ribs are adradial or tertiary, and arise in pairs from the four large perradial basal arches of the thorax, which become bisected by the four primary ribs. Peristome irregularly denticulate.
Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.32 broad.
Habitat.—North Pacific (off Japan), Stations 236 to 239, surface.
18. Sethophormis floscula, n. sp.
Cephalis small, hemispherical, with subregular, small hexagonal pores. Thorax flatly conical, with larger hexagonal meshes and twenty-four ribs; four of these are perradial and prolongations of the four collar bars; four interradial arise from the collar ring between the former, alternating with them. Each of these eight main ribs gives off two more or less irregular, lateral branches (one at each side), altogether sixteen. The thorax is similar to Cladarachnium ramosum (Pl. [55], fig. 5), whilst the cephalis is quite different. Peristome with twenty-four prominent triangular lobes.