horn of the same length. Thorax and abdomen together ovate, gradually lessening towards the constricted mouth, which is only half as broad. Pores irregular, roundish, in the thorax twice to four times as broad as in the abdomen. Both joints are separated by an oblique, internal, lumbar septum, which in some specimens observed was more oblique than in that figured; some specimens had a very irregular form.
Dimensions.—Length of the three joints, a 0.025 to 0.03, b 0.06 to 0.07, c 0.03 to 0.04; breadth, a 0.04, b 0.09, c 0.08.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.
12. Theocorys alauda, Haeckel.
Shell nearly spindle-shaped, decreasing from the thicker middle towards both ends. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 5. Cephalis subspherical, with a strong, conical horn of three times the length. Thorax campanulate, with numerous regular, circular, quincuncial pores. Abdomen inversely ovate, slender, twice as broad as the truncated mouth, with irregular, roundish pores, three to four times as large as those of the thorax.
Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.03, b 0.08, c 0.1.
Habitat.—Fossil in Barbados and in Tertiary rocks of Sicily.
13. Theocorys apollinis, n. sp. (Pl. 69, fig. 3).
Shell ovate, with two deep strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 5 : 7. Cephalis subspherical, with a large, straight, cylindrical horn, about as long as the whole shell (in the specimen figured this is broken off). Thorax truncate, conical. Abdomen subglobose, truncate on both poles, twice as broad as the constricted mouth. Pores quincuncial, subregular, circular, twice as broad in the abdomen as in the thorax.
Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.05, c 0.07.
Habitat.—South Atlantic, Station 332, surface.
14. Theocorys sphærophila, Haeckel.
Shell almost ovate, rough, with two slight strictures. Length of the three joints = 2 : 7 : 10, breadth = 3 : 8 : 12. Cephalis subspherical, with a strong, conical horn of the same length. Thorax nearly spherical, with subregular, circular pores of different sizes. Abdomen ovate, truncate at both poles, nearly twice as broad as the constricted mouth, with very large, subregular, hexagonal pores, four to six times as broad as the bars, in three to four transverse, and ten to twelve longitudinal rows.
Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.1; breadth, a 0.03, b 0.08, c 0.12.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.
