Shell nut-shaped, smooth, with deep sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger square annular pores. Basal plate also with four larger collar pores. Apical horn twice as long as the shell, conical. Three primary feet (the apical and the two pectoral) slender, curved, as long as the horn; three secondary feet (the sternal and the two tergal) are half as long as the former and more highly inserted; all six feet strongly divergent, cylindrical, pointed. _Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.15 long, feet 0.08 to 0.14 long. _Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms. 2. _Hexaspyris setigera_, Haeckel. _Ceratospyris setigera_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 11. _Ceratospyris setigera_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. figs. 11_a_, 11_b_. Shell nut-shaped, tuberculate, with a complete internal sagittal ring and numerous small circular pores. Basal plate with four larger central and a circle of twelve to twenty smaller peripheral pores. Apical horn half as long as the shell, bristle-shaped. Three primary feet longer and more deeply inserted than the three secondary feet; all six feet strongly divergent, bristle-shaped, shorter than the shell. _Dimensions._--Shell 0.06 long, 0.09 broad; horn 0.03 long; primary feet 0.05, secondary 0.02 long. _Habitat._--Fossil in Barbados. 3. _Hexaspyris bütschlii_, Haeckel. _Ceratospyris triomma_, Bütschli (_non_ Ehrenberg), 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 12, _a_, _b_. Shell nut-shaped, spinulate, with a complete internal sagittal ring and subregular circular pores. Basal plate with twelve pores (four larger central and eight smaller peripheral). Apical horn stout, oblique, as long as the shell. Six feet of equal length, slightly divergent, nearly vertical, slender, three to four times as long as the shell. _Dimensions._--Shell 0.05 long, 0.07 broad; horn 0.06, feet 0.15 to 0.2 long. _Habitat._--Fossil in Barbados. {1048}4. _Hexaspyris spinosa_, Haeckel. _Petalospyris spinosa_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 98, Taf. iii. fig. 14. Shell subspherical, smooth, with slight sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger pores. Basal plate with two large pores only. Apical horn short, pyramidal, three primary feet half as long as the shell and twice as long as the three secondary feet. All six feet pyramidal, slightly divergent. _Dimensions._--Shell 0.05 long, 0.07 broad; horn 0.02, feet 0.02 to 0.04 long. _Habitat._--Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta). 5. _Hexaspyris ophirensis_, Haeckel. _Petalospyris ophirensis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. ix. fig. 24.