Pores subregular, circular, without frames, of different sizes, about twice as broad as the bars. Radial bristles three times as long as one pore. Mouth with five or six strong, conical teeth, twice as long as the bristles.
Dimensions.—Diameter of the shell 0.3 to 0.36, of the pores 0.02 to 0.03.
Habitat.—Tropical Atlantic, Stations 347 to 349, surface.
5. Castanella balfouri, n. sp.
Pores irregular, roundish, two to three times as broad as the bars. Bristles about one-fourth as long as the radius. Mouth with four strong conical teeth, forming a cross, somewhat longer and much thicker than the bristles.
Dimensions.—Diameter of the shell 0.22 to 0.28, of the pores 0.01 to 0.02.
Habitat.—North Pacific, Stations 240 to 245, surface.
6. Castanella channeri, n. sp.
Pores irregular, roundish, two to four times as broad as the bars. Bristles nearly half as long as the radius. Mouth with seven to nine short conical teeth, shorter than the bristles, but much thicker.
Dimensions.—Diameter of the shell 0.3 to 0.4, of the pores 0.02 to 0.025.