Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.
10. Sethophormis triloba, n. sp.
Cephalis large, hemispherical, distinctly trilobed, with dense, irregular, polygonal network. From the centre of its top diverge three stout arches or semilunar rods, which are curved downwards, and unite with the three horizontal, radial beams of the collar-septum inside the collar-ring. These three parietal arches of the cephalis are much stronger than in the similar preceding species (Pl. [57], fig. 9), and between them are placed three vaulted bosoms of the cephalis. The collar-ring and the thorax are of the same form as in the preceding, but possess only four concentric, nine-angled rings.
Dimensions.—Cephalis 0.05 long, 0.08 broad; thorax 0.24 diameter.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
11. Sethophormis enneastrum, n. sp.
Cephalis very large, flat, cap-shaped, with hexagonal base, trilobed, of similar form and structure to the two preceding species. The flat, discoidal thorax has also the same form, with nine stout ribs and five concentric, nine-angled rings; its forty-five large meshes, however, are not so simple as these (Pl. [57], fig. 9), but are subdivided into irregular, smaller meshes by interpolated radial beams connecting the concentric rings.
Dimensions.—Cephalis 0.1 diameter, thorax 0.3 diameter.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
12. Sethophormis arachnium, n. sp.