Page:Scientific results HMS Challenger vol 18 part 1.djvu/286

78 Dimensions.—Diameter of the outer shell 0.42, inner 0.4, distance of both 0.01; diameter of the meshes 0.02 to 0.06.

Habitat.—North Pacific, Station 250, surface.

5. Liosphæra polypora, n. sp. (Pl. 20, fig. 2).

Both shells with small irregular roundish pores, of about the same size as the bars between them; twenty to thirty on the quadrant. The pores of the outer shell somewhat smaller, therefore much more numerous than the pores of the inner shell. Distance between the two shells about one-third as great as the radius of the inner. Both shells connected by numerous thin radial beams. Surface smooth or a little rough.

Dimensions.—Diameter of the outer shell 0.18, inner 0.14, distance of both 0.02; pores and bars 0.003 to 0.005.

Habitat.—West Tropical Pacific, Station 225, depth 4475.

Definition.— with three concentric spherical lattice-shells, which are united by radial beams.

Definition.— with two medullary (intracapsular) shells and one cortical (extracapsular) shell.

The genus Thecosphæra comprises a large number of triple-shelled, formerly united with Actinomma, but different from this genus in the absence of radial spines. The latticed shell is composed of three concentric spheres, two of which lie within the central capsule (medullary shells), and one outside (cortical shell). This latter is connected with the former by radial beams piercing the wall of the central capsule. From the following Rhodosphæra (with one medullary and two cortical shells) Carposphæra differs also by the distance of the three shells. In the former the distance between the two outer shells is much smaller, in the latter much larger, than the distance between the inner shells.

Definition.—Pores of the cortical shell regular, hexagonal, or circular, with hexagonal frames or lobes, all of nearly equal size and form.