All twenty spines of nearly equal size and form, nearly as long as the diameter of the shell, conical; both equatorial spines of the hydrotomical axis about one-third longer than the eighteen others. Crests between the dimples of the shell-surface serrated, forming around the basal half of each spine a conical truncate sheath with crested surface and serrated mouth, the teeth of which are prolonged into short by-spines. (Similar to Hexaconus vaginatus, Pl. [139], fig. 7, but differing in the nearly equal size of all the spines and in the double thickness of the shell-wall.)
Dimensions.—Major axis of the shell 0.12, minor 0.1, length of the spines 0.08, basal breadth 0.01.
Habitat.—North Pacific, Station 253, surface.
3. Coleaspis obscura, n. sp.
All twenty spines of nearly equal size and form, little longer than their large cylindrical sheaths, which are nearly as long as the radius of the shell, and armed on the truncated mouth with strong triangular by-spines, both equatorial spines of the hydrotomical axis one and a half times as long as the eighteen others. Shell very dark and thick walled, quite opaque.
Dimensions.—Major axis of the shell 0.1, minor 0.08; length of the spines 0.06, of their sheaths 0.04.
Habitat.—Arctic Ocean, Greenland, Koch, surface.
4. Coleaspis occulta, n. sp.
All twenty spines of nearly equal size and form, quite concealed in their long cylindrical sheaths, which are somewhat longer than the radius of the shell, and armed on the truncated mouth with acute simple teeth; each sheath deeply sulcated, apparently resulting from the concrescence of numerous parallel leaf-shaped by-spines. Small shell very dark and thick-walled, quite opaque.
Dimensions.—Major axis of the shell 0.08, minor 0.06; length of the spines and their sheaths 0.05 to 0.06.