Definition.—Pores of the spherical shell irregular, of unequal size or form; surface smooth or a little rough, without thorns.
10. Xiphostylus trogon, n. sp. (Pl. [14], fig. 12).
Lithomespilus trogon, Haeckel, 1881, Prodrom. et Atlas.
Pores irregular, roundish or subcircular, two to three times as broad as the bars; ten to twelve on the half equator. Surface smooth. Major polar spine three-sided prismatic, once and a half to twice as long as the axis of the sphere; minor spine quite rudimentary, scarcely longer than broad, but surrounded by a group of from three to six similar short spines.
Dimensions.—Diameter of the sphere 0.1, pores 0.005 to 0.015, bars 0.005 to 0.008; length of the major spine 0.15 to 0.18, of the minor 0.01 to 0.02, basal breadth 0.02.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
11. Xiphostylus falco, n. sp. (Pl. [13], fig. 14).
Pores irregular, roundish, two to five times as broad as the bars; sixteen to eighteen on the half equator. Surface smooth. Polar spines cylindrical, very stout, nearly half as thick as the radius of the shell; major spine two to four times as long as the diameter of the shell; minor spine obliquely inserted, scarcely longer than the diameter, divided at the end into two short, hook-shaped, curved branches.
Dimensions.—Diameter of the sphere 0.08, pores 0.002 to 0.005, bars 0.001; breadth of the spines 0.02, length of the major spine 0.15 to 0.2, of the minor 0.09.
Habitat.—South Pacific, Station 302, depth 1450 fathoms.