3. Castanidium buchanani, n. sp. (Pl. 113, fig. 7).
Pores regular, circular, without frames, twice as broad as the bars, of variable size. Bristles five to six times as long as one pore. Radial main-spines numerous, straight, slender, cylindrical, about as long as the diameter of the shell.
Dimensions.—Diameter of the shell 0.25 to 0.3, of the pores 0.012 to 0.02.
Habitat.—Tropical Atlantic, Stations 346 to 349, surface.
4. Castanidium murrayi, n. sp. (Pl. 113, figs. 5, 5a).
Pores subregular, circular, without frames, three times as broad as the bars. Bristles three times as long as one pore. Radial main-spines cylindrical, stout, irregularly curved, longer than the shell-diameter, covered with longish hexagonal dimples, which are separated by a network of prominent crests (fig. 5a).
Dimensions.—Diameter of the shell 0.4 to 0.5, of the pores 0.02 to 0.025.
Habitat.—North Atlantic, Station 352 to 354, surface.
5. Castanidium aldrichi, n. sp.
Pores subregular, circular, without frames, of variable size, about as broad as the bars. Bristles four times as long as one pore. Radial main-spines conico-cylindrical, irregularly curved, straight, about as long as the radius. (The conical base of the spines is inflated and fenestrated, therefore the shell is nearly polyhedral.)
Dimensions.—Diameter of the shell 0.35 to 0.4, of the pores 0.012 to 0.015.
Habitat.—Central Pacific, Stations 270 to 274, surface.
6. Castanidium bromleyi, n. sp.
Pores irregular, roundish, two to four times as broad as the bars. Bristles half as long as the radius. Radial main-spines cylindrical, straight, slender, longer than the shell-diameter.
Dimensions.—Diameter of the shell 0.22 to 0.26, of the pores 0.006 to 0.02.
Habitat.—Indian Ocean and Southern Pacific, Stations 162 to 169, surface.
7. Castanidium bethelli, n. sp.
Pores irregular, roundish or polygonal, two to three times as broad as the bars. Bristles one-third as long as the radius. Radial main-spines conico-cylindrical, irregularly curved, with dimpled surface, somewhat longer than the radius.
Dimensions.—Diameter of the shell 0.5 to 0.6, of the pores 0.015 to 0.03.
Habitat.—North Pacific, Stations 235 to 245, surface.
