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.
Habitat.—Indian Ocean, Madagascar, Rabbe.
Subgenus 2. Xiphacanthidium, Haeckel.
Definition.—Apophyses of the radial spines broad, compressed, wing-shaped, formed like a large thin plate. Edges of the spines commonly broad, strongly prominent.
7. Xiphacantha stauroptera, n. sp.
Spines four-winged, from the middle part little thinner towards both ends. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, isosceles triangular or truncated quadrangular; their base is about half as broad as their length, and occupies in the basal half of each spine about one-sixth to one-eighth of its length.
Dimensions.—Length of the spines 0.1 to 0.15; greatest breadth (diagonal of the cross of the apophyses) 0.006 to 0.009.
Habitat.—South Atlantic, Station 332, surface.
8. Xiphacantha trigonoptera, n. sp.
Spines four-winged, tapering rapidly from the broad middle part towards both ends. Apex simple pyramidal. Base with a small wing-cross. Four apophyses equilateral triangular; their base occupies the middle of each spine, extending to about one-fifth of its length.
Dimensions.—Length of the spines 0.15 to 0.2, greatest breadth (diagonal of the cross of the apophyses) 0.06 to 0.08.
Habitat.—Central Pacific, Station 272, surface.
9. Xiphacantha macroptera, n. sp.
Spines four-winged, from the broad middle part gradually thinner towards both ends. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, very long and broad,
