Habitat.—Tropical zone of the Atlantic, coast of Brazil, Rabbe, surface.
2. Acrosphæra echinoides, n. sp. (Pl [8], fig. 1).
Shell a regular sphere, covered with numerous, straight, radial spines, irregularly scattered over the whole surface. In the half meridian of the shell twenty to thirty irregular roundish pores of variable size, one to four times as broad as the bars. Spines conical, strong, quite radial, at the top of small conical elevations, which are perforated by from three to six pores.
Dimensions.—Diameter of the shell 0.12 to 0.15, of the pores 0.002 to 0.008; length of the spines 0.015, of their basal zones 0.01.
Habitat.—South-east corner of the Pacific, Valparaiso, Station 298, surface.
3. Acrosphæra setosa, Haeckel.
Polysolenia setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 10.
Shell a regular sphere, covered with numerous bristle-shaped radial spines, irregularly scattered between the pores. In the half meridian of the shell two to four very large circular pores (equal to one-third the radius), and between them numerous very small, point-like pores.
Dimensions.—Diameter of the shell 0.05 to 0.08, of the large pores 0.01, of the small 0.001; length of the spines 0.01 to 0.02.
Habitat.—West Tropical Pacific, Philippine Sea, Station 206, depth 2100 fathoms.