Cortical shell covered with short conical by-spines and irregular roundish pores, three to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8. Six radial spines three-sided prismatic, at the distal end club-shaped; two major spines three times as long as the four others, which are equal to the shell radius.
Dimensions.—Diameter of the outer shell 0.16, middle 0.06, inner 0.02.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
Subfamily Hexacromyida,[[113]] Haeckel, 1881, Prodromus, pp. 449, 453.
Definition.—Cubosphærida with four concentric spherical lattice-shells.
Genus 82. Hexacromyum,[[114]] Haeckel, 1881, Prodromus, p. 453.
Definition.—Cubosphærida with four concentric lattice-spheres and six simple spines of equal size.
The genus Hexacromyum possesses four concentric, spherical, or octahedral lattice-shells; two inner medullary shells within the central capsule, two outer cortical outside it. The four spheres are connected by six radial beams, which are prolonged outside into simple spines of equal size, opposite in pairs in the three dimensive axes. This genus can be derived from Hexacontium by duplication of the cortical shell.
1. Hexacromyum elegans, n. sp. (Pl. [24], fig. 9).
Shell composed of four concentric shells, with radial proportion = 1 : 2.5 : 7.5 : 10. First (innermost) shell with very small circular pores, second shell with larger circular pores. Third shell (inner cortical shell) with large, subregular, circular, hexagonally framed pores (eight to nine on the radius), twice as broad as the bars; from the elevated nodal-points of the hexagonal frames (between every three pores) arise thin bristle-shaped radial beams, which are united at the distal end by vaulted branches forming the delicate fourth shell. Surface smooth. Radial spines three-sided pyramidal, as long as the radius, as broad at the base as the innermost shell.