2. Phacostylus amphixiphus, n. sp.
Disk with smooth surface, three times as broad as the outer, and eight times as broad as the inner medullary shell. Pores irregular, roundish; ten to eleven on the radius. Margin of the disk simple, smooth, without spines and equatorial girdle. Both polar spines sword-shaped triangular, two-edged, about as long as the radius of the disk, and as broad at the base as the inner medullary shell.
Dimensions.—Diameter of the disk 0.15, of the outer medullary shell 0.05, of the inner 0.02; length of the polar spines 0.08, basal breadth 0.02.
Habitat.—Indian Ocean, Madagascar, Rabbe, surface.
Subgenus 2. Astrostylus, Haeckel.
Definition.—Margin of the disk with a solid equatorial girdle or a corona of radial spines.
3. Phacostylus amphipyramis, n. sp.
Disk with spiny surface, four and a half times as broad as the outer, and fourteen times as broad as the inner medullary shell. Pores irregular, roundish; eight to ten on the radius. Margin of the disk with a corona of irregular, radial spines. Both opposite polar spines pyramidal, twice as long as broad, and nearly as long as the radius of the disk.
Dimensions.—Diameter of the disk 0.22, of the outer medullary shell 0.05, of the inner 0.016; length of the polar spines 0.1, basal breadth 0.05.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.