Dimensions.—Length of the shell (with eight joints) 0.16, length of each joint 0.02; greatest breadth (in the fifth joint) 0.07.
Habitat.—Mediterranean, French shore, St. Tropez (J. Müller), surface.
3. Eucyrtidium hexagonatum, n. sp. (Pl. 80, fig. 11).
Shell smooth, ovate, with six to seven internal septal rings. All joints (except the first) nearly of the same length; the sixth joint is the broadest. The seventh and eighth joints (broken off in the specimen figured) gradually decrease toward the constricted mouth, which is as broad as the septum between the third and fourth joints. Cephalis and thorax together pear-shaped, with circular pores, sharp lumbar stricture, and a stout, pyramidal horn of the same length. The five or six abdominal joints with regular, hexagonal pores, six or seven in course of the length of each joint.
Dimensions.—Length of the shell (with eight joints) 0.2, length of each joint 0.025 to 0.03; greatest breadth (in the sixth joint) 0.1.
Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.
4. Eucyrtidium fusiforme, n. sp.
Shell smooth, slender, spindle-shaped, without external strictures, but with ten to twelve internal septal rings. All joints of the same length; the sixth joint is the broadest. Cephalis conical, with a pyramidal horn of the same length. Pores regular, circular, four or five in course of the length of each joint. (Differs from all other species of the genus in the regular, slender, spindle form; the constricted mouth of the last joint is half as broad as the sixth joint.)
Dimensions.—Length of the shell (with twelve joints) 0.24, length of each joint 0.02; greatest breadth (on the sixth joint) 0.06, of the mouth 0.03.
Habitat.—Indian Ocean, Maldive Islands (Haeckel, 1882), surface.
5. Eucyrtidium doliolum, n. sp.
Shell smooth, barrel-shaped, or nearly spindle-shaped, with eight or nine distinct strictures. All joints (except the first) of the same length; the fourth joint is the broadest. Cephalis small, subspherical, with two short, divergent, conical horns. Pores regular, circular, hexagonally framed, three to four in course of the length of each joint.
Dimensions.—Length of the shell (with ten joints) 0.2, length of each joint 0.022; greatest breadth (in the fourth joint) 0.08.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
Subgenus 2. Stichocyrtis, Haeckel, 1881, Prodromus, p. 438.
Definition.—All joints of the shell nearly of the same length (excepting often the first). Surface spiny.
