Dimensions.—Radius of each arm (without terminal spine) 0.32, basal breadth 0.03, terminal breadth 0.1.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
7. Stauralastrum antiquum, n. sp.
Rhopalastrum sp. Bury, 1862, Polycystins of Barbados, pl. xiv. fig. 5.
Arms six times as long as broad at their base, in their distal half nearly spherical, three times as broad as in their cylindrical basal half; their distal breadth nearly equals the diameter of the central disk which exhibits three to four rings. On the end of each arm one strong, angular, terminal spine. (Differs from the preceding species by larger central disk and stouter arms, also by less developed spines.) Edges of the arms parallel.
Dimensions.—Radius of each arm 0.25, basal breadth 0.04, terminal breadth 0.12.
Habitat.—Fossil in the Barbados rocks; and living in the depths of the Central Pacific, Station 266, depth 2750 fathoms.
8. Stauralastrum staurolonche, n. sp.
Arms four times as long as broad at their base, gradually increasing towards their truncated end, which is one and a half times as broad as their base; their distal breadth equals the radius of the central disk, which exhibits four to five rings. At the end of each arm is a very strong conical terminal spine. (Resembles Histiastrum quaternarium, Abhandl. k. Akad. Wiss. Berlin, 1875, Taf. xxiv. fig. 3, but has no patagium.) Edges of the arms rectilinear, divergent.
Dimensions.—Radius of each arm 0.25, basal breadth 0.045, distal breadth 0.07.