4. Phacostylus caudatus, n. sp. (Pl. [32], fig. 6).
Astrosestrum caudatum, Haeckel, 1881, Prodromus et Atlas (pl. xxxii. fig. 6).
Disk with smooth surface, two and a half times as broad as the outer, and six times as broad as the inner medullary shell. Pores regular, circular; six to seven on the radius of the disk. Margin with a solid equatorial girdle, and irregularly bordered with eight to ten conical spines; two opposite of these are much longer than the others. (This species can be derived from Astrosestrum, two opposite marginal spines being much more strongly developed than the six to eight others.)
Dimensions.—Diameter of disk 0.12, of the outer medullary shell 0.05, of the inner 0.02; length of the polar spines 0.1 to 0.25, basal breadth 0.025.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
5. Phacostylus maximus, n. sp.
Disk with smooth surface, five times as broad as the outer, and ten times as broad as the inner medullary shell. Pores regular, circular; twenty to twenty-two on the radius. Margin with a solid equatorial girdle, bearing on the periphery one hundred to one hundred and twenty plain teeth, and two very large polar spines, which are cylindrical, longer than the diameter of the disk, and as broad at the furrowed base as the radius of the outer medullary shell. (Similar to Sethostylus dentatus, Pl. [34], fig. 1, but much larger, and with a double medullary shell.) Dimensions.—Diameter of the disk 0.4, of the outer medullary shell 0.08, of the inner 0.04; length of the polar spines 0.5, basal breadth 0.04.
Habitat.—Fossil in the rocks of Barbados.
Genus 187. Triactiscus,[[226]] Haeckel, 1881, Prodromus, p. 457.
Definition.—Phacodiscida with simple medullary shell, and with three radial spines on the margin of the disk, placed in the equatorial plane.