Spines stout, four-sided, in the proximal half prismatic, in the distal half pyramidal, with emarginated apex. Base with very large wing-cross. Four apophyses about in the middle of each spine, compressed, straight, two-edged, with emarginated ends, about twice as long as the basal breadth of the spine. Central capsule small, pellucid.
Dimensions.—Length of the spines 0.2 to 0.3, breadth 0.02 to 0.03; length of the apophyses 0.04 to 0.06.
Habitat.—South Pacific, Station 291, surface.
5. Xiphacantha falcata, n. sp.
Spines slender, four-sided prismatic, gradually thickened from both ends towards the middle part, with simple apex. Base with very small wing-cross. Four apophyses about in the middle part of each spine, falcated, compressed, recurved, twice to three times as long as the greatest breadth of the spine.
Dimensions.—Length of the spines 0.3 to 0.4, greatest breadth 0.015; length of the apophyses 0.03 to 0.05.
Habitat.—Central Pacific, Station 270, surface.
6. Xiphacantha ancorata, n. sp.
Spines slender, four-sided prismatic, gradually thickened from the narrow base towards the short, simple, pyramidal apex. Base with large wing-cross. Four apophyses on the distal end, immediately below the pyramidal apex, falcated, strongly recurved, like an anchor with four strong teeth.
Dimensions.—Length of the spines 0.4 to 0.5, basal breadth 0.005, distal breadth 0.015; length of the apophyses 0.04.