Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.003; length of the spines 0.08, basal breadth 0.02.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
17. Acanthosphæra compacta, n. sp.
Shell thick walled, about sixty times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Thirty to forty radial spines, three-sided pyramidal, scarcely half as long as the radius, five to six times as broad at the base as one pore.
Dimensions.—Diameter of the shell 0.24, pores 0.004, bars 0.002; length of the radial spines 0.05, basal breadth 0.02.
Habitat.—Fossil in Barbados.
Subgenus 3. Raphidodrymus, Haeckel.
Definition.—Pores of the spherical shell irregular, of different size or form. Radial spines arising from all the nodal-points of the network.
18. Acanthosphæra capillaris, n. sp.
Shell thin walled, with irregular polygonal meshes, twelve to twenty times as broad as the bars; eight to ten on the radius. Radial spines bristle-shaped, arising from all the nodal-points of the network, about as long as the diameter of the largest meshes.