Page:Scientific results HMS Challenger vol 18 part 2.djvu/555

Rh 17. Theocapsa schwannii, n. sp.

Shell slenderly ovate, or pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 2 : 4 : 7. Cephalis subspherical, small, with a stout, pyramidal horn of three times the length. Cavity of the thorax subspherical, its thick wall with small, regular, circular, hexagonally-framed pores. Abdomen very thick-walled, with crested bars, and very large, irregular, roundish pores. Basal pole rounded, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.14, breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

18. Theocapsa mülleri, n. sp. (Pl. 66, fig. 7).

Shell slenderly ovate, or pear-shaped, spiny, with two indistinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a stout, pyramidal horn of the same length, and with a variable number of smaller accessory horns. Pores irregular, roundish, three to four times as broad in the inflated abdomen as in the thorax. Basal pole hemispherical, spiny.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

19. Theocapsa sarsii, n. sp.

Shell pear-shaped, with two indistinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 4. Cephalis with a thick horn of the same length, conical. Abdomen subspherical, very thick-walled, its pores regular, circular, twice as broad as the bars, and three times as broad as those of the thorax. Basal pole flat, rounded.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.12; breadth, a 0.05, b 0.11, c 0.15.

Habitat.—Fossil in Barbados.

20. Theocapsa darwinii, n. sp. (Pl. 66, fig. 12).

Shell pear-shaped, with two distinct strictures. Length of three joints = 1 : 1 : 5, breadth = 1 : 2 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with small, regular, circular pores. Abdomen broad, ovate, with larger, regular, circular, hexagonally-framed pores. Basal pole hemispherical.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.2; breadth, a 0.04, b 0.08, c 0.2.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

Definition.— (vel Tricyrtida eradiata clausa) without apical horn, with a terminal lattice-plate on the mouth.