long as broad, with slightly convex outlines; its pores subregular, circular, half as broad as the cephalis.
Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.15 long, 0.14 broad.
Habitat.—Fossil in Barbados.
3. Sethoconus pileus, n. sp.
Cephalis subspherical, free, with distinct collar stricture, a conical oblique horn of the same length, and small, irregular, roundish pores. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, half as broad as the cephalis, with very thin bars.
Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.16 broad.
Habitat.—Central Pacific, Stations 262 to 274, surface.
4. Sethoconus ampliatus, Haeckel.
Cephalis, hemispherical, thorny, with a conical horn of twice the length; it is separated from the thorax by a complete internal collar septum, but without external collar stricture. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, about as large as the cephalis, with thin bars.
Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.08 long, 0.18 broad.
Habitat.—Fossil in Barbados.
5. Sethoconus mitra, Haeckel.
Cephalis ovate, with slight collar stricture (not distinct enough in Ehrenberg's figure), with few large pores, and a conical stout horn of the same length. Thorax campanulate, conical, twice as long as broad, with slightly convex outlines; its pores subregular, roundish, increasing in size towards the mouth, the largest as broad as the cephalis.
Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.12 long, 0.07 broad.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; fossil in Barbados.
6. Sethoconus rayianus, n. sp. (Pl. 58, fig. 6).
Cephalis ovate, with obliterated collar stricture (but distinct internal septum), with small, irregular pores, and two to four divergent horns, which are longer than the cephalis, and two or three of which are forked. Thorax tent-shaped, conical, two-thirds as long as broad, with slightly
