Page:Scientific results HMS Challenger vol 18 part 1.djvu/279

Rh Dimensions.—Diameter of the shell 0.1, length of the tubes 0.04, breadth 0.01, basal distance 0.01.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

Definition.— with one single latticed sphere, with simple shell-cavity; with shell-pores, which are prolonged on the inside into centripetal, conical, or cylindrical tubuli.

The genus Sethosphæra differs from its ancestral form, Cenosphæra, by the production of internal, centripetal, radial tubuli on the inside of the shell (the contrary of the preceding genus Ethmosphæra). It corresponds therefore to the social Pharyngosphæra; but in the latter the formation of the shell and its tubes is more or less irregular, whilst in the former each regular pore is prolonged into a regular tubule.

1. Sethosphæra entosiphonia, n. sp.

Shell with smooth surface and regular circular pores, separated by hexagonal frames, twice as broad as the bars. Six to eight on the quadrant. Each pore is prolonged on the inside of the shell in a short conical centripetal tube, twice as long as its diameter.

Dimensions.—Diameter of the shell 0.15, outer pores 0.008, bars 0.004, length of the tubuli 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Sethosphæra entosolenia, n. sp.

Shell with smooth surface and regular circular pores, without hexagonal frames, of about the same breadth as the bars. Ten to twelve on the quadrant. Each pore is prolonged on the inside of the shell into a thin cylindrical centripetal tube, three times as long as its diameter.

Dimensions.—Diameter of the shell 0.2, outer pores and bars 0.006, length of the tubuli 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

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

Carposphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.—Liosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, both connected by radial beams piercing the central capsule.