3. Tripocalpis tricostata, n. sp.
Shell ovate campanulate, one and a half times as long as broad, with regular circular pores, disposed in alternate longitudinal rows. Apical horn three-sided pyramidal, stout, half as long as the shell. In the middle of the shell there arise three wing-like lateral ribs, which are prolonged into three broad, slightly curved, divergent terminal feet.
Dimensions.—Shell 0.12 long, 0.08 broad, horn and feet 0.06 to 0.08.
Habitat.—Fossil in Barbados.
4. Tripocalpis triserrata, n. sp. (Pl. [51], fig. 6).
Shell ovate, nearly twice as long as broad. The three sides of the shell, between the three large ribs, are provided each with nine delicate parallel, longitudinal, slightly curved ribs, alternating with ten longitudinal rows of regular circular pores about as broad as the bars. Apical horn short and broad, three-sided pyramidal; from the three edges of its base there arise three wing-like serrate main ribs, which are prolonged into three short pyramidal terminal feet.
Dimensions.—Shell 0.12 long, 0.07 broad, horn and feet 0.01.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
5. Tripocalpis cortinaris, n. sp. (Pl. [97], fig. 3).
Shell hemispherical, one and a half times as broad as long, with regular, circular, hexagonally framed pores, Apical horn stout, three-sided pyramidal, with three serrate edges. From the base of the latter arise three strongly dentate and curved lateral ribs, with recurved teeth, and these are prolonged into the serrate convex edge of the three basal feet, which are crescentic and twice as long as the shell.