1. Theocalyptra veneris, n. sp.
Shell flatly campanulate, very delicate and fragile, very similar to Eucecryphalus agnesæ (Pl. [59], fig. 3), but without collar spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 7 : 9. Cephalis hemispherical, with a single bristle-shaped horn of twice the length. Thorax subconical, separated from the flatter abdomen by a deep stricture, with thin bars, and large, subregular, hexagonal meshes, increasing in size towards the smooth mouth-edge.
Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.04; breadth, a 0.025, b 0.15, c 0.1.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many stations, surface.
2. Theocalyptra orci, Haeckel.
Halicalyptra orci, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. x. figs. 9, 10.
Shell flatly campanulate, very similar to the preceding species in general form and fenestration, but flatter and smaller, with different proportions. Length of the three joints = 7 : 2 : 1, breadth = 1 : 6 : 8. Cephalis hemispherical, very small, with two divergent, bristle-shaped horns of the same length. Abdomen nearly horizontally expanded.
Dimensions.—Length of the three joints, a 0.015, b 0.04, c 0.01; breadth, a 0.02, b 0.12, c 0.16.
Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).
3. Theocalyptra discoides, Haeckel.