Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 5 : 4. Pores circular, simple, twice as broad as the bars; eight to ten on the half equator. Medullary shell circular, one-third as broad as the cortical shell. Polar spines furrowed and angular; the longer and thinner pyramidal about as long as the main axis, the shorter and thicker scarcely half as long, thickened towards the short conical apex.
Dimensions.—Major axis 0.08 to 0.1, minor 0.06 to 0.08; pores 0.01, bars 0.005; diameter of the medullary shell 0.03; length of the large polar spine 0.08 to 0.12, of the shorter 0.04 to 0.05.
Habitat.—Fossil in the Tertiary rocks of Barbados; also living in the depths of the Pacific, central area, Stations 265 to 268, depth 2700 to 2900 fathoms.
Subgenus 3. Druppatractona, Haeckel.
Definition.—Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface smooth, without thorns or papillæ.
8. Druppatractus lævis, Haeckel.
Stylosphæra lævis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 6.
Cortical shell thin walled, smooth, with irregular network. Proportion of the two axes = 3 : 2. Pores roundish or subcircular, of different size, one-half to twice as broad as the bars; eight to ten on the half equator. Medullary shell ellipsoidal, one-third as large as the cortical shell. Polar spines conical, the larger and thinner nearly as long as the main axis, the shorter and thicker scarcely one-third as long.
Dimensions.—Major axis 0.07 to 0.1, minor 0.05 to 0.07; pores and bars 0.005 to 0.01; axes of the medullary shell 0.03 and 0.02; length of the major polar spine 0.06 to 0.09, of the shorter 0.03 to 0.04.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface.