Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.
2. Archipera pentacantha, n. sp.
Shell pear-shaped, smooth, with numerous and small irregular roundish pores. Basal plate with three larger pores. Two horns and three feet of nearly equal size and similar form, three-sided prismatic, about as long as the shell diameter, somewhat curved. The apical horn stands on the apex, the frontal horn half-way up the shell.
Dimensions.—Shell 0.08 long, 0.06 broad; horns and feet 0.05 to 0.07 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
3. Archipera bicornis, n. sp.
Shell ovate, rough, with small regular circular, sparsely scattered pores. Basal plate with four larger central and a peripheral coronal of twelve smaller pores. Two horns near the apex widely divergent, somewhat shorter than the shell, of equal size and similar form. Three feet twice as long, horizontally expanded. All five spines slender, three-sided pyramidal, straight.
Dimensions.—Shell 0.07 long, 0.06 broad; horns 0.05 long, feet 0.1 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
4. Archipera tricornis, n. sp.