Page:Scientific results HMS Challenger vol 18 part 2.djvu/446

1322 1. Theopilium tricostatum, n. sp. (Pl. 70, fig. 6).

Shell flatly conical, smooth. Length of the three joints = 1 : 4 : 2, breadth = 2 : 6 : 10. Cephalis subspherical, with a thin oblique horn of the same length. Thorax with three stout ribs in its wall, and with subregular, hexagonal pores increasing in size towards the girdle. Abdomen flatter than the thorax, without ribs, nearly horizontal, with subregular, square pores, disposed in four to six concentric, subcircular series of different sizes; decreasing in size towards the wide open mouth. Seen from the side, this species resembles Corocalyptra agnesæ, (Pl. 59, fig. 3).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Central Pacific, Stations 260 to 274, surface.

2. Theopilium triradiatum, n. sp.

Shell flatly conical, smooth, in general of the same form as, and with similar fenestration to, the preceding species, but different in the proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 4 : 6. Cephalis hemispherical, with two divergent, thin horns of the same length. Thorax more elevated, about as high as broad. The three divergent ribs are not limited to the thorax, but prolonged through the whole abdomen, the outline of which is a prolongation of that of the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.05; breadth, a 0.05, b 0.1, c 0.15.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Theopilium cranoides, Haeckel.

Eucyrtidium cranoides, Haeckel, 1862, Monogr. d. Radiol., p. 320, Taf. vii. figs. 1-3.

Shell campanulate-conical, smooth. Length of the three joints = 2 : 5 : 4, breadth = 3 : 9 : 10. Cephalis ovate, with a straight, excentric, prismatic horn of the same length. The campanulate thorax is separated from it by no external collar stricture, but by an internal septum. From the base of the horn arise three divergent radial ribs, running in the wall of the two first joints to the lumbar stricture (loc. cit., Taf. vii. fig. 3). Abdomen short and wide, without ribs. Pores rather large, regular, circular, quincuncial, in the cephalis smaller. Central capsule four-lobed.

Dimensions.—Length of the three joints, a 0.027, b 0.054, c 0.047; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Mediterranean (Messina), surface.

Definition.— (vel Tricyrtida triradiata aperta) with three simple, free, lateral wings, arising from the collar stricture between cephalis and thorax.

The genus Corocalyptra comprises a small number of very elegant hat-shaped Tricyrtida, which resemble greatly Eucecryphalus among the Dicyrtida. As in the