2. Microcubus pentacircus, n. sp.
All twelve gates simple. Frontal ring on the sides convex, not constricted by the equatorial ring. All rings tuberculate, with irregular roundish knots. No larger basal spines. Similar to the preceding species; but the five rings are much thicker and tuberculate (not thorny); the twelve gates are therefore relatively smaller.
Dimensions.—Length of the shell 0.1, breadth 0.12.
Habitat.—Fossil in Barbados.
3. Microcubus zonarius, n. sp. (Pl. [94], fig. 8).
All twelve gates simple, ovate. Frontal ring on the sides convex, not constricted by the equatorial ring, nearly twice as broad as long. All rings thorny, very thin, except only the broad angular sagittal ring. No larger basal spines.
Dimensions.—Length of the shell 0.08, breadth 0.15.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
4. Microcubus quadrupes, n. sp.
All twelve gates simple, square. Frontal ring square, not constricted by the equatorial ring. All rings smooth, quadrangular. Basal ring with four short vertical conical feet, two of which (right and left) are inferior prolongations of the frontal ring, and arise from the lateral corners of the basal gates; two others are prolongations of the sagittal ring (sternal and caudal), and arise from the medial corners of the basal gates. (The shell is like a small cube with four feet.)