Page:Scientific results HMS Challenger vol 18 part 2.djvu/518

1394 both poles, and resembles greatly the triradiate Rhopalocanium. It may be derived from the latter by interpolation of three secondary or interradial wings between the three primary or perradial apophyses.

1. Hexalatractus sexalatus, n. sp.

Shell ovate, smooth, with two distinct strictures, length of the three joints = 3 : 6 : 9, breadth = 4 : 9 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen inversely conical; both with subregular, circular pores. Six divergent wings arise, beginning from the collar stricture, from the upper half of the shell, with broad triangular base; they are little curved downwards, with the convexity outside, and gradually tapering towards the distal end; the latter lies in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Stations 263, depth 2650 fathoms.

2. Hexalatractus fusiformis, n. sp. (Pl. 68, fig. 13).

Shell rough, nearly spindle-shaped, with sharp collar and slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 7. Cephalis hemispherical, with a conical horn of the same length. Thorax hemispherical with regular, circular, hexagonally-framed pores. Abdomen inversely conical, with irregular, roundish pores. From the upper half of the abdomen arise, with broad triangular base, six divergent wings, which are nearly straight, and slightly fenestrated at the base; their conical distal ends do not reach the horizontal plane, in which the basal apex of the abdomen lies.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Definition.— (vel Tricyrtida multiradiata clausa) with nine lateral wings on the abdomen.

The genus Theophæna differs from the preceding six-radiate Hexalatractus in the possession of nine lateral wings, and may be derived from the triradiate Rhopalocanium by interpolation of six secondary wings between the three primary apophyses.

1. Theophæna corona, n. sp. (Pl. 70, fig. 12).

Shell rough, nearly spindle-shaped, with two sharp strictures. Length of the three joints = 4 : 9 : 16, breadth = 5 : 12 : 10. Cephalis hemispherical, very thick-walled, with a conical horn of