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.
2. Spongoxiphus prunococcus, n. sp. (Pl. [17], figs. 12, 13).
Spongostylus prunococcus, Haeckel, 1881, Prodromus, p. 455, et Atlas, pl. xvii. figs. 12, 13.
Cortical shell one and a third times as long as broad, with smooth surface. Spongy framework very compact, with very small meshes, its thickness about equals the breadth of the outer medullary shell. Both medullary shells ellipsoidal, the outer three times as large as the inner. Polar spines very stout, three-sided pyramidal, about half as long as the cortical shell, on the base about as broad as the outer medullary shell. (Differs from the preceding in the ellipsoidal form of both medullary shells, and in the finer structure of the spongy framework.)
Dimensions.—Length of the cortical shell 0.18 to 0.2, breadth 0.14 to 0.16; thickness of the spongy wall 0.035 to 0.04; length of the outer medullary shell 0.04 to 0.06, breadth 0.03 to 0.04.
Habitat.—Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.