Dimensions.—Major axis of the shell 0.14 to 0.16, minor axis 0.10 to 0.12; pores 0.015, bars 0.004; major axis of the medullary shell 0.04 to 0.05, minor (horizontal) axis 0.02 to 0.03; length of the twenty radial spines 0.18 to 0.24, basal breadth 0.01.
Habitat.—South Pacific, Station 300, depth 1375 fathoms.
6. Amphitholus armatus, n. sp.
Central chamber twice as broad, but of the same height, as the flat vaulted cupolas. Surface armed with thirty to forty very large three-sided prismatic spines, longer than the major axis of the shell. Pores irregular, roundish, twice to five times as broad as the bars; eight to nine on the basal semicircle of one cupola.
Dimensions.—Major axis of the shell 0.15, minor axis 0.1; pores 0.006 to 0.015, bars 0.003; length of the spines 0.2 to 0.25, breadth 0.01.
Habitat.—North Atlantic, Station 353, surface.
7. Amphitholus polyacanthus, n. sp.
Central chamber of the same breadth and height as both cupolas. Surface armed with very numerous (sixty to eighty) strong conical spines, about as long as the minor axis of the shell. Pores subregular, circular, twice as broad as the bars; sixteen to eighteen in the basal semicircle of one cupola.
Dimensions.—Major axis of the shell 0.13, minor 0.08; pores 0.006, bars 0.003; length of the radial spines 0.09, breadth 0.006.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.