Habitat.—South Pacific, Station 288, surface.
Genus 78. Hexalonchidium,[[108]] Haeckel, 1881, Prodromus, p. 451.
Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes in pairs; the two opposite spines of each pair equal, the three pairs unequal.
The genus Hexalonchidium exhibits the same relation to Hexalonche that Hexastylidium bears to Hexastylus; the growth of the three spine-pairs is different, whilst both spines of each pair are equal; they correspond therefore to the three axes of a rhombic crystal.
1. Hexalonchidium axonometrum, n. sp.
Cortical shell thin walled, covered with short bristle-shaped by-spines, twice as broad as the medullary shell; both with regular hexagonal meshes, twice to three times as broad as the bars (inner meshes half as broad as the outer). All three spine-pairs three-sided prismatic, of very different length but of equal breadth (equal to three pores). Major spine-pair twice as long as the shell diameter; middle pair about equal to the latter, minor scarcely half as long. (Similar to Hexalonche anaximandri, Pl. [22], fig. 5, but distinct in the different length of the spines.)
Dimensions.—Diameter of the outer shell 0.12, inner 0.06; length of the major spines 0.25, middle 0.1, minor 0.04.
Habitat.—Indian Ocean, Madagascar, surface, Rabbe.
Subfamily Hexacontida,[[109]] Haeckel, 1881, Prodromus, pp. 449, 452.
Definition.—Cubosphærida with three concentric, spherical, or octahedral lattice-shells.