Habitat.—Tropical Pacific, many Stations (200, 224, 271, &c.), surface, and in various depths.
2. Theocyrtis barbadensis, Haeckel.
Eucyrtidium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 7.
Shell thin-walled, smooth. Length of the three joints = 2 : 4 : 5, breadth, 2 : 5 : 4. Cephalis ovate or conical, with a strong, conical horn, without external stricture, dilated into the campanulate thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, circular, quincuncially disposed, of about the same breadth as the bars.
Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.08.
Habitat.—Fossil in the Tertiary rocks of Barbados.
3. Theocyrtis cylindrica, Haeckel.
Eucyrtidium cylindricum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 1.
Shell elongate, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a thick, pyramidal horn of the same length (the edges of the horn giving to it the appearance of being composed of two converging spines). Thorax truncated, conical. Abdomen perfectly cylindrical, much elongated. Pores subregular, circular, twice as broad as the bars, quincuncially disposed. Mouth wide open, truncate.
Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.03, b 0.06, c 0.06.