5. Axodiscus trigonus, n. sp.
Ring regular, triangular, equilateral, connected with the central chamber by six radial beams of alternating length and distance; therefore three smaller (perradial) chambers (with denser and darker network) alternating with three larger (interradial) chambers (with looser and finer network). On the margin three strong conical radial spines, arising in the radius of the larger chambers. (Differs from Archidiscus pyloniscus, Pl. [48], fig. 11, mainly in the strong angular spines on the three corners of the triangular shell.)
Dimensions.—Diameter of the ring 0.05, of the central chamber 0.014.
Habitat.—South Pacific, Station 296, depth 1825 fathoms.
6. Axodiscus octogonus, n. sp.
Ring circular or nearly octagonal, connected with the central chamber by eight radial beams at nearly equal distances, which are prolonged outside into eight short conical spines. (Differs from Archidiscus octoniscus in the marginal prolongation of the eight beams.)
Dimensions.—Diameter of the ring 0.04, of the central chamber 0.013.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
7. Axodiscus spinosus, n. sp.
Ring circular, connected with the central chamber by ten to twelve radial beams at nearly equal distances, which are prolonged outside into short conical spines of variable length. (May be regarded as an aculeate variety of Archidiscus polythalamus.)