Shell subspherical, compressed, rough, with slight sagittal stricture and ovate internal primary ring. Basal plate with four large collar pores (fig. 13_a_, _loc. cit._). The other lattice-work with irregular small roundish pores. Apical horn and the three feet short and thick, scarcely half as long as the shell, with a roundish spinulate knob at the distal end. _Dimensions._--Length of the shell 0.07 long, 0.08 broad; horn and feet 0.02 to 0.03 long. _Habitat._--Fossil in Barbados. 11. _Tripospyris tessaromma_, n. sp. Shell nearly cubical, spiny, with deep sagittal stricture and subcircular ring. Basal plate with four large collar pores. Facial and occipital plates each also with two pairs of large square annular pores; lateral pores irregular polygonal. Apical horn half as long as the feet, which are three times the length of the shell, cylindrical, slightly curved. _Dimensions._--Shell 0.1 long, 0.12 broad; horn 0.15 long, feet 0.3 long. _Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms. Subgenus 4. _Tripospyromma_, Haeckel. _Definition._--Basal plate with six or more collar pores. Commonly two small anterior jugular pores, two large middle cardinal pores, and two small posterior cervical pores; sometimes several small accessory collar pores. 12. _Tripospyris hexomma_, n. sp. (Pl. 95, fig. 4). Shell thorax-shaped, tuberculate, with deep sagittal stricture and semicircular internal primary ring. Basal plate with three pairs of pores. Facial plate with two pairs, occipital plate with four pairs of large annular pores. Lateral pores smaller, irregular, polygonal. Apical horn and caudal foot half as long as the shell and as the two pectoral feet; all four spines cylindrical, two to three times as long as the shell, slightly curved. _Dimensions._--Shell 0.1 long, 0.12 broad; horn and feet 0.2 to 0.4 long. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms. {1029}13. _Tripospyris semantidium_, n. sp. Shell nut-shaped, thorny, with sharp sagittal stricture and subcircular ring. Basal plate with three pairs of large pores. Facial and occipital plates each with three pairs of large squarish pores. Lateral pores small and numerous, irregular roundish. Apical horn half as long as the shell and the three feet; all four spines straight, cylindrical, with thickened club-shaped end. _Dimensions._--Shell 0.12 long, 0.13 broad; horn 0.06 long, feet 0.15. _Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms. 14. _Tripospyris eucolpos_, n. sp. (Pl. 84, fig. 4). Shell thorax-shaped, smooth, with two vaulted bosoms, separated by a deep sagittal stricture and an internal primary ring. Basal plate constricted, with three pairs of collar pores. The other lattice-work with subregular circular pores. Apical horn and the three feet shorter than the shell, straight, divergent; their inner half thinner, cylindrical, smooth, their outer half an ovate dimpled cone.