Diploconus saturnus, Haeckel, 1879, Natürl. Schöpfungsgesch., Aufl. vii. p. 706, Taf. xvi. fig. 11.
Mantle of the double cone compressed, thick walled, with elliptical transverse section; its contour convex; its surface with numerous deep and irregular longitudinal furrows and marginal incisions. Diameter of its mouth one-third as long as the whole shell and twice as broad as its equatorial diameter. The two hydrotomical spines short, scarcely longer than their sheath. The eighteen other spines thin, cylindrical, nearly of the same length, curved. (Resembles a sheaf.)
Dimensions.—Length of the shell 0.24; equatorial breadth 0.04, polar breadth 0.07.
Habitat.—South Pacific, Station 300, surface.
7. Diploconus hexaphyllus, n. sp. (Pl. [140], fig. 2).
Mantle of the double cone compressed, thick walled, with elliptical transverse section; its contour straight; surface with six stronger and numerous smaller straight ribs and six marginal denticulate incisions. Diameter of its mouth one-third as long as the whole shell and somewhat smaller than the equatorial diameter. Hydrotomical spines about twice as long as their sheath, pyramidal, with emarginate point and six wings. Geotomical spines short and strong, pyramidal. Sixteen other spines thin, straight, conical.
Dimensions.—Length of the shell 0.3; equatorial breadth 0.11, polar breadth 0.1.
Habitat.—Central Pacific, Station 266, surface.
Genus 381. Diplocolpus,[[421]] n. gen.
Definition.—Diploconida with only two developed, very large spines (opposite in the hydrotomical axis); all the other eighteen spines quite rudimentary or externally atrophied.