Page:Scientific results HMS Challenger vol 18 part 1.djvu/703

Rh 10. Porodiscus perispira, n. sp. (Pl. 41, fig. 2).

Perispira perforata, Haeckel, 1881, Prodromus.

Inner rings of the disk (two or three) concentric, outer rings (three or four) spirally convoluted, spiral line simple. All rings nearly of the same breadth, connected by alternating irregular radial beams. Pores irregular, two to three on the breadth of each ring.

Dimensions.—Diameter of the disk (with six rings) 0.17; breadth of each ring 0.016; pores 0.003 to 0.005.

Habitat.—Pacific, central area, Stations 272 to 274, surface.

11. Porodiscus radiatus, n. sp.

Perispira radiata, Haeckel, 1881, Prodromus.

Inner rings of the disk (four or five) concentric, outer rings (three or four) spirally convoluted, spiral line simple. All rings connected by piercing radial beams (eight in the inner half, sixteen in the outer half). Breadth of the rings and of the pores increasing from the centre towards the periphery, three to four pores on the breadth of each ring.

Dimensions.—Diameter of the disk (with eight rings) 0.18; breadth of the second ring 0.006, of the eighth ring 0.02; pores 0.002 to 0.006.

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

Definition.—The inner rings of the disk spirally convoluted, the outer rings concentric (commonly circular).

12. Porodiscus centrospira, n. sp. (Pl. 41, fig. 6).

Centrospira perispongidium, Haeckel, 1881, Prodromus.

Inner rings of the disk (two or three) spirally convoluted (with simple or double spiral line), outer rings (three or four) concentric, subcircular. All rings nearly of the same breadth, connected by alternating radial beams. Pores subregular, two to three on the breadth of each ring. Lattice-work in the periphery of the disk a little spongy (as in Pl. 41, fig. 11).

Dimensions.—Diameter of the disk (with five rings) 0.15; breadth of each ring 0.015; pores 0.003.

Habitat.—Pacific, central area, Station 267, depth 2700 fathoms.

Definition.—All rings of the disk spirally convoluted, forming parts of a simple or double spiral turning.