8. Sethophormis octalactis, n. sp.
Cephalis large, hemispherical, with irregular, polygonal pores. Thorax flatly campanulate, with regular, hexagonal pores, and eight stout, regularly-disposed, radial ribs reaching the margin at equal distances. Four of these correspond to the four primary ribs of Tetraphormis cruciata, and exhibit at their base a larger pair of basal pores, surrounded by a semicircular ring (Pl. [70], fig. 5); the other four are secondary, interpolated. Peristome circular, simple.
Dimensions.—Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.22 broad.
Habitat.—Indian Ocean, Madagascar (Rabbe), surface.
Subgenus 5. Enneaphormis, Haeckel, 1881, Prodromus, p. 432.
Definition.—Thorax with nine radial ribs, three of which are the primary beams, the other six being secondary and interpolated.
9. Sethophormis rotula, n. sp. (Pl. [57], fig. 9).
Enneaphormis rotula, Haeckel, 1881, Prodromus et Atlas, pl. lvii. fig. 9.
Cephalis very large, flat, cap-shaped, trilobed, with irregular, polygonal network. Horizontal collar-ring stout, hexagonal, with three larger and three alternate smaller sides of half the length. From the middle of the three larger sides arise three horizontal, centripetal, radial beams, which are united in the centre of the collar-septum—the three primary cortinar beams. These are prolonged outside into three centrifugal primary ribs of the thorax. From the six corners of the collar-ring arise six other secondary, thoracic ribs, equal in size and similar in form to the three primary. Each of these nine equal, straight ribs of the thorax is thickened towards the distal end, and bears at equal distances five pairs of opposite (tangential) lateral branches. The opposite branches of the neighbouring spines become united, and lie nearly horizontally in one plane, so that the flat, discoidal thorax is like a nine-angled wheel with nine equally distant spokes and five concentric, nine-angled rings.
Dimensions.—Cephalis 0.12 diameter, thorax 0.36 diameter.