8. Theocyrtis ptychodes, n. sp. (Pl. 69, fig. 8).
Shell almost cylindrical, smooth. Length of the three joints = 1 : 3 : 3, breadth = 2 : 4 : 4. Cephalis hemispherical, with a large, conical, curved horn of twice the length. Thorax very large, inflated, campanulate, thick-walled. Abdomen cylindrical, with a thin folded wall (like a petticoat), the thickness of which decreases gradually towards the wide truncate mouth. Pores subregular, circular, and quincuncially disposed in the two first joints, irregular and larger in the abdomen, forming longitudinal series between the folds.
Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.11; breadth, a 0.05, b 0.12, c 0.12.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
9. Theocyrtis aspera, Haeckel.
Shell almost cylindrical, with rough or thorny surface. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 5. Cephalis subspherical, small, with a short conical horn. Thorax hemispherical, inflated. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax subregular, circular, quincuncially disposed, in the abdomen irregular roundish, two to four times as large.
Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.06 to 0.07, c 0.08 to 0.1; breadth, a 0.02, b 0.1, c 0.1.
Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; fossil in Barbados.
10. Theocyrtis proserpinæ, n. sp.
Shell almost cylindrical, smooth. Length of the three joints = 3 : 6 : 9, breadth = 2 : 8 : 7. Cephalis subspherical, with a stout conical horn. Thorax campanulate. Abdomen cylindrical. Pores regular, circular, quincuncially disposed, double-edged in the thorax, and three to four times as large as in the cephalis and the abdomen.
Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.02, b 0.08, c 0.07.
Habitat.—North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.
11. Theocyrtis oenophila, Haeckel.
Shell in the apical half conical, in the lower cylindrical. Length of the three joints = 2 : 5 : 6, breadth = 3 : 8 : 7. Cephalis subspherical, with a large prismatic horn, which is bulbous at the base, and armed with three teeth at the distal apex. Thorax conical, constricted at the base, with subregular, circular, quincuncial pores. Abdomen cylindrical, with a coronal of nine large
