3. Sethocorys armadillo, Haeckel.
Shell slenderly ovate, smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 6. Cephalis ovate, at the apex thorny, with a conical horn of the same length. Thorax smooth, ovate, truncate, with small, regular, circular pores, disposed in from twelve to fifteen transverse rows of the same breadth as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, hyaline, prominent peristome.
Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.06 broad.
Habitat.—Fossil in Barbados.
4. Sethocorys odysseus, n. sp. (Pl. 62, fig. 10).
Shell ovate, smooth, with obliterated collar stricture. Length of the two joints = 2 : 9, breadth = 4 : 8. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax nearly spherical, with regular, circular pores, of the same breadth as the cephalic pores, quincuncially disposed. Mouth constricted, only one-third as broad as the thorax, with a broad, hyaline, prominent peristome.
Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.08 broad.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
5. Sethocorys amphora, Haeckel.
Shell ovate, mouth with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis hemispherical, with a short conical horn of half the length. Thorax ovate, truncate, with small, regular, circular, quincuncial pores. Mouth constricted, half as broad as the thorax, with a narrow, prominent, hyaline peristome.
Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.07 long, 0.06 broad.
Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr).
6. Sethocorys ajacis, n. sp.
Shell slenderly ovate, smooth, without external collar stricture, but with an internal septum. Length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis conical, with a large pyramidal horn of twice the length, and sometimes with a smaller accessory horn at its base; its pores scarce, irregular. Thorax ovate, truncate, hyaline, in the greater part without pores, in the smaller part
