Page:Scientific results HMS Challenger vol 18 part 1.djvu/478

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Definition.— with spongy spherical or polyhedral shell (with or without enclosed concentric lattice-shells).

Definition.— with solid spongy sphere, with numerous simple radial spines, but without latticed medullary shells.

The genus Spongiomma differs from its ancestral form, Styptosphæra, in the development of simple radial spines on the surface of the solid sphere, the entire mass of which is composed of an irregular, spongy wicker-work.

Definition.—Radial spines on the surface of the spongy sphere all of the same shape.

1. Spongiomma radiatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, irregular, polyhedral meshes and very thin thread-like bars. From the surface arise very numerous (one hundred and twenty to one hundred and sixty or more) straight, bristle-shaped radial spines, as long as the radius of the sphere (counting from the middle part of it).

Dimensions.—Diameter of the spongy sphere 0.2; length of the radial spines 0.1.

Habitat.—Central Pacific, Station 272, surface.

2. Spongiomma denticulatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, almost equal meshes, four to eight times as broad as the thin, elegantly denticulated bars; from the surface arise very numerous (two hundred to three hundred or more) curved, radial spines, as long as the radius, and of the same form as the bars.

Dimensions.—Diameter of the sphere 0.25; length of the spines 0.12.

Habitat.—Central Pacific, Station 274, surface.

3. Spongiomma spathillatum, n. sp.

Spongy framework in the central part of the sphere much denser and darker, and with smaller meshes than in the peripheral part in which are very thin bars. Entire surface covered with