Definition.—Each radial spine with three rows of verticillate lateral branches (a row arising from each edge of the spine).
5. Hexancistra mirabilis, n. sp. (Pl. [23], fig. 3).
Hexapitys mirabilis, Haeckel, 1881, Prodromus, p. 451.
Cortical shell very thin walled, three times as broad as the medullary shell. Inner shell spherical, with very delicate, subregular hexagonal meshes; seven to eight on the half diameter. Outer shell octahedral, with irregular polygonal meshes of very different size; on the surface numerous thin accessory radial spines, equal in length to its radius. Six main spines, extremely long and stout, many times longer than the diameter of the outer shell, nearly as broad as the radius of the inner shell, three-sided prismatic, with sharp, prominent, spirally twisted edges; on every edge a great number of thin lateral branches, arranged perpendicularly to it, as long as the diameter of the outer shell, and pinnated by ten to twenty pairs of delicate secondary spinules, biserial and perpendicular to the primary branches. (In the figured specimen the spherical central capsule, between both shells, was well preserved; its nucleus nearly filled the medullary shell. The thick jelly-veil around it was radially striped and octahedral.)
Dimensions.—Diameter of the outer shell 0.13, of the inner 0.05; length of the spines 0.5 to 0.8 or more, breadth 0.02.
Habitat.—Central Pacific, Station 271, surface.
Genus 77. Hexaloncharium,[[107]] n. gen.
Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes; one opposite pair larger than the two others.
The genus Hexaloncharium exhibits the same relation to its ancestral form, Hexalonche, that Hexastylarium bears to Hexastylus. Two opposite spines of one pair are larger than the four others, and correspond to the three axes of a quadratic crystal.
1. Hexaloncharium octahedrum, n. sp.