Page:Scientific results HMS Challenger vol 18 part 2.djvu/260

1136 feet, and connected in the apex of the pyramidal or campanulate shell with the apical horn. It may probably be derived from Dictyophimus by loss of the cephalis. The central capsule is simple, spherical, or ellipsoidal.

1. Tripocalpis plectaniscus, n. sp.

Shell three-sided pyramidal, smooth, about as long as broad, with irregular polygonal pores and thin bars. Apical horn stout, three-sided pyramidal, about as long as the shell. From the three edges of its base arise three prominent straight radial ribs, which are prolonged into three large divergent feet, of equal size and the same form as the horn.

Dimensions.—Shell 0.1 diameter, horn and feet 0.12.

Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

2. Tripocalpis galea, Haeckel.

Halicalyptra galea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. ii. fig. 10.

Shell campanulate, rough, about as long as broad, with irregular roundish pores and thick bars. Apical horn stout, three-sided pyramidal, scarcely one-fourth as long as the shell. Beyond its base there arise three prominent, slightly curved lateral ribs, which are prolonged into three pyramidal, slightly divergent stout feet, somewhat shorter than the shell.

Dimensions.—Shell 0.08 to 0.09 diameter, horn 0.02, feet 0.07.

Habitat.—Fossil in Barbados.

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.