Arms trifid, three times as long as broad at their base; each arm with three pointed terminal branches, ending in strong sulcate spines; the middle branch twice as large as the two others. The simple basal part of each arm two and a half times as long as the trifid distal part.
Dimensions.—Radius of the arm 0.35, basal breadth 0.03, greatest breadth (in the distal part) 0.05.
Habitat.—South Pacific, Station 298, surface.
Subgenus 3. Tetracranastrum, Haeckel.
Definition.—Each cross-arm with four terminal branches, the two fork-branches being again bifurcated.
8. Dicranastrum bifurcatum, n. sp. (Pl. [47], figs. 1, 1a).
Arms doubly forked or quadripartite, six times as long as broad at their base; each arm in its proximal half simple, three times as long as broad; in its distal half doubly forked; the secondary branches with blunt, roundish ends, nearly as large as the primary branches. Central disk (fig. 1a) with three concentric rings around the central chamber; from its periphery radiate thin radial beams in the spongy framework of the delicate arms. The central capsule has the same form as the skeleton, and is only a little smaller.
Dimensions.—Radius of the arm 0.45, basal breadth 0.08; breadth of the terminal branches 0.03.
Habitat.—North Pacific, east of Japan, Station 241, surface.