2. Acrocubus tesseralis, n. sp.
Mitral ring of the same size as the basal ring; both rings square, smooth, with straight outlines. Sagittal ring also square, smooth. Four columellæ straight. Nodal points without radial spines. The shell has the form of a regular geometrical cube, the edges of which are represented by the rings.
Dimensions.—Height of the frontal ring 0.1, breadth 0.11.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
Subgenus 2. Dipocubus, Haeckel.
Definition.—Basal ring with two descending feet.
3. Acrocubus brachiatus, n. sp.
Mitral ring smaller than the basal, both rings square, with thick straight rods. Sagittal ring tuberculate, square, equatorial part thinner. Four columellæ curved, the two lateral ones prolonged downwards into two vertical parallel straight feet of half their length.
Dimensions.—Diameter of the cube 0.12; length of the feet 0.06.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.