17. Challengeron channeri, John Murray.
Challengeron channeri, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 12.
Shell subcircular, lenticular, strongly compressed, with fourteen to eighteen slender, straight, radial spines on the margin; the spines are straight, equidistant, cylindrical, and about as long as the radius of the shell. Peristome short, with two parallel, vertical, lateral, straight teeth, which are less than half the length of a spine.
Dimensions.—Diameter of the shell 0.14 to 0.17; length of the spines 0.06 to 0.08.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
18. Challengeron moseleyi, n. sp. (Pl. [99], fig. 14).
Shell circular, lenticular, strongly compressed, with thirty to forty slender, straight, equidistant, radial spines on the margin, larger and smaller spines alternating; the larger spines are about as long as the radius, the smaller only half as long. Peristome short, tubular, with two divergent ovate or nearly triangular teeth, a dorsal and a ventral, about as long as the shorter marginal spines.
Dimensions.—Diameter of the shell 0.13 to 0.15; length of the larger spines 0.06 to 0.07, of the smaller 0.03 to 0.04.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
19. Challengeron bethelli, John Murray.