Subgenus 1. Acanthocorallium, Haeckel.
Definition.—Thorax with six divergent ribs or radial beams (three primary or perradial alternating with three secondary or interradial).
1. Acanthocorys hexapodia, n. sp.
Cephalis large, ovate, with subregular hexagonal pores, and six strong, conical, simple, divergent horns of the same length. Thorax flat, conical, smooth, with six large triangular basal holes, separated by six strong, prismatic, smooth beams, which are connected only near the distal end by a hexagonal ring of delicate, irregular network. Collar septum with three meshes, separated by the three centripetal prolongations of the three primary ribs.
Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.24 broad.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
2. Acanthocorys pristipodia, n. sp.
Cephalis large, hemispherical, with irregular, polygonal pores, and numerous (ten to twenty) bristle-shaped, radiating horns, which are conical at the base, and twice as long. Thorax flatly campanulate, thorny, with six strong, serrate or spinulate, divergent, radial ribs, prolonged into six free conical feet of the same length. Meshes of the thorax irregular, polygonal, a corona of six larger ones at the base. Collar septum with four meshes, shaped as in Pl. 56, fig. 6.
Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18 broad.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
3. Acanthocorys macropodia, n. sp.
Cephalis small, subspherical, with irregular, roundish pores and numerous small, bristle-shaped horns. Length of the two joints = 1 : 2, breadth = 1 : 6. Thorax sexangular, pyramidal, with six very long and straight, widely divergent feet, which are prismatic and spiny, and three to five times as long as the breadth of the shell. Only the upper third of the six ribs is connected by irregular, roundish network, with six large triangular holes at the base. Collar septum with four meshes which have the same relation to the six ribs as in Sethophormis hexalactis (Pl. 56, fig. 6).
Dimensions.—Cephalis 0.025 diameter, thorax 0.05 long, 0.15 broad.
Habitat.—Central Pacific, Station 271, surface.
4. Acanthocorys bütschlii, Haeckel.
Cephalis large, subspherical, with numerous small, circular pores and three to six divergent, slender, apical horns. Thorax flatly conical, smooth, not much larger than the cephalis, with six
