4. Tholostaurus octobelonis, n. sp.
Two opposite cupolas larger than the two others. Pores subregular, circular, three times as broad as the bars; ten to twelve in the semicircle of one cupola. Eight long and thin, needle-shaped, radial spines, in pairs crossed in two diagonal planes.
Dimensions.—Major axis of the shell 0.16, minor 0.12; pores 0.01, bars 0.003.
Habitat.—South Pacific, Station 291, surface.
5. Tholostaurus dodecabelos, n. sp.
Two opposite cupolas larger than the two others. Pores irregular, roundish, twice to three times as broad as the bars; six to eight in the semicircle of one cupola. Twelve thin and long radial spines, four on the poles of the two crossed axes (principal and lateral), eight crossed in two diagonal planes.
Dimensions.—Major axis of the shell 0.14, minor 0.11; pores 0.006 to 0.01, bars 0.003.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
6. Tholostaurus polybelonis, n. sp.
Two opposite cupolas larger than the two others. Pores circular, hexagonally framed, of the same breadth as the bars; ten to twelve in the semicircle of one cupola. Numerous (twenty to thirty or more) thin, bristle-like, radial spines, about as long as the radius of the shell.