Subgenus 1. Petalospyrantha, Haeckel.
Definition.—Basal plate with two large collar pores only, separated by the base of the primary ring.
1. Petalospyris foveolata, Ehrenberg.
Shell campanulate, smooth, with distinct sagittal stricture and subregular circular pores. Basal plate with two large collar pores only. Apical horn and the eight feet slender, conical, slightly curved, about as long as the shell; feet somewhat divergent (often seven or nine instead of eight).
Dimensions.—Shell diameter 0.04 to 0.05; length of the horn and the feet 0.04 to 0.05.
Habitat.—Fossil in Barbados.
2. Petalospyris floscula, n. sp.
Shell nut-shaped, tuberculate, with deep sagittal stricture and subregular circular pores. Basal plate with two large triangular pores only. Apical horn slender, conical, twice as long as the shell. Twelve to sixteen feet flattened, leaf-shaped, broad, slightly divergent, as long as the shell, with truncate distal end.
Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.12 long, feet 0.05 to 0.07 long.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
Subgenus 2. Petalospyrella, Haeckel.
Definition.—Basal plate with three large collar pores (two paired posterior cardinal, and an odd anterior sternal pore).
3. Petalospyris triomma, n. sp. (Pl. 87, fig. 14).
Shell nut-shaped, tuberculate, with sharp sagittal stricture and irregular roundish pores. Basal plate with three large pores and three alternate smaller. Apical horn stout, conical, half as long as the shell. Twelve to fifteen feet, divergent, curved, pointed, as long as the horn.
Dimensions.—Shell 0.06 long, 0.08 broad; horn and feet 0.03 long.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
4. Petalospyris platyacantha, Ehrenberg.
Shell campanulate, smooth, with slight sagittal stricture and small irregular roundish pores. Basal plate with three large pores (?). Apical horn very strong, three-sided pyramidal, twice as
