Page:Scientific results HMS Challenger vol 18 part 1.djvu/561

Rh Dimensions.—Length of the cortical shell 0.18, breadth 0.14; thickness of its wall 0.035; diameter of the outer medullary shell 0.04, of the inner 0.02.

Habitat.—South Atlantic, Station 325, surface.

6. Spongoliva daturina, n. sp.

Cortical shell one and a half times as long as broad, armed with numerous, thick and short, conical radial spines, about as long as the outer medullary shell. Spongy framework compact, with small meshes, its thickness equal to half the length of the outer ellipsoidal medullary shell.

Dimensions.—Length of the cortical shell 0.24, breadth 0.16; thickness of its wall 0.025; diameter of the outer medullary shell 0.045 to 0.035, of the inner 0.025.

Habitat.—Pacific, central area, Station 272, surface.

Definition.— with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus Spongoxiphus differs from Spongoliva by the development of two strong spines in the axis of the shell, on its two opposite poles. From the similar Spongatractus it differs in the duplication of the medullary shell. It may also be regarded as a Stylatractus, in which the simple latticed cortical shell is replaced by an irregular spongy framework.

1. Spongoxiphus sphærococcus, n. sp.

Cortical shell one and a half times as long as broad, with thorny surface. Spongy framework compact, with small meshes, its thickness equal to the radius of the outer medullary shell. Both medullary shells spherical, the outer three times as broad as the inner. Polar spines very stout, conical, slightly sulcated, about half as long as the cortical shell, as broad at the base as the outer medullary shell. (Differs from Spongatractus pachystylus almost only in the double medullary shell.)

Dimensions.—Length of the cortical shell 0.18, breadth 0.12; thickness of the spongy wall 0.025; diameter of the outer medullary shell 0.05, of the inner 0.016.

Habitat.—Fossil in the rocks of Barbados (Haeckel); also living in the Pacific, central area, Station 265, depth 2900 fathoms.