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).
Conarachnium rayianum, Haeckel, 1881, Prodromus, p. 430.
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 concave outlines, and subregular, hexagonal pores, gradually increasing towards the mouth, the largest half as broad as the cephalis. This elegant species is dedicated to Dr. Ray, the discoverer of many rare Radiolarians in the Challenger collection.
Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.12 broad.
Habitat.—Central Pacific, Stations 266 to 272, surface.
7. Sethoconus cervus, Haeckel.
? Eucyrtidium cervus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 21.