Page:Scientific results HMS Challenger vol 18 part 2.djvu/371

Rh 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.

Cephalis very large, flat, cap-shaped, trilobed, with hexagonal base, of the same structure as in the three preceding species. The flat discoidal thorax is also similar, and has the same structure as in the preceding species (Pl. 57, fig. 9); but the number of concentric, nine-angled rings is raised from five to eight, and in its outer part nine secondary radial beams are interpolated between the nine primaries, so that the peristome has not nine but eighteen corners.

Dimensions.—Cephalis 0.08 diameter, thorax 0.4 diameter.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

13. Sethophormis enneactis, n. sp.

Cephalis small, hemispherical, with small, irregular, polygonal pores. Thorax flatly pyramidal, nearly discoidal, with nine prominent, stout ribs, which are connected by numerous (twelve to sixteen) horizontal, nine-angled rings. In the outer half of the thorax there are nine weaker secondary ribs interpolated between the nine stronger primaries, and eighteen shorter and feebler tertiary ribs between the former and the latter. Peristome denticulated, nine-angled.

Dimensions.—Cephalis 0.03 diameter, thorax 0.08 long, 0.24 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

14. Sethophormis eupilium, n. sp. (Pl. 56, fig. 9).

Sethopyramis eupilium, Haeckel, 1882, Atlas, pl. lvi. fig. 9.

Craspedilium eupilium, Haeckel, 1878, Manuscript.

Cephalis very small, hemispherical, hyaline, without pores. Thorax flatly pyramidal, with nine concave, triangular faces and nine little curved, stout, radial beams. Between these are interpolated numerous incomplete secondary beams, which are absent in the apical part of the thorax. The radial beams being connected by numerous (thirty to forty or more) horizontal, ring-like threads, a delicate arachnoidal network with small, quadrangular pores is produced. Peristome nine-angled, with a peculiar vertical gallery, composed of four horizontal, parallel, nine-angled rings, which are connected by numerous vertical, parallel bars, therefore with three transverse rows of square pores. This peculiar species is very different from the preceding and may represent a separate genus, Craspedilium.

Dimensions.—Cephalis 0.01 diameter, thorax 0.1 long, 0.25 broad.

Habitat.—Central Pacific, Station 271, surface.