4. Sethophormis asteriscus, n. sp.
Cephalis large, flat, cap-shaped, with irregular polygonal pores. Thorax flat, campanulate, with subregular, hexagonal pores, and five stout ribs. The marginal distance between the two anterior (lateral) ribs is twice as great as the distance between every two other ribs (the postero-lateral ribs being basal branches of the antero-lateral ribs). Peristome with a double corona of short, conical spines.
Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.17 broad.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
5. Sethophormis astrodiscus, n. sp.
Cephalis small, flatly vaulted, cap-shaped with irregular polygonal pores. Thorax very flatly vaulted, nearly discoidal, with subregular hexagonal pores, and five stout ribs. The marginal distance between all five ribs is nearly equal. Peristome denticulate with an elegant corona of small square pores and short conical thorns.
Dimensions.—Cephalis 0.015 long, 0.035 broad; thorax 0.05 long, 0.2 broad.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
Subgenus 3. Hexaphormis, Haeckel, 1881, Prodromus, p. 432.
Definition.—Thorax with six radial ribs (three primary perradial and three secondary interradial beams).