Page:Scientific results HMS Challenger vol 18 part 2.djvu/517

Rh polygonal pores, and a terminal row of very small square pores. Lumbar and terminal coronals of similar shape, each with twenty to thirty short divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Diplocyclas bicincta, n. sp.

Shell campanulate, in general of the same form as, and similar fenestration to, the preceding species but not so slender, and with different proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 5 : 5. Cephalis hemispherical, with a single, conical, simple horn. Pores of the thorax hexagonal, of increasing size (in eight to ten transverse rows). Abdomen with smaller square pores (in four to six rows). The two coronals of the same shape as in Pl. 59, fig. 8.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Diplocyclas bizonalis, n. sp.

Shell subconical, with indistinct collar and distinct lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with two divergent conical horns of equal size. Thorax conical, with small, irregular, double-edged pores, and a terminal corona of about nine very large pores. Abdomen truncate, conical, with three to four transverse rows of roundish, quadrangular, very large pores. Lumbar and terminal coronals of similar shape, each with twelve to fifteen triangular divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Definition.— with the basal mouth of the shell fenestrated (vel Tricyrtida multiradiata clausa).

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

The genus Hexalatractus, and the following genus Theophæna, represent together the small subfamily Theophænida, or those Tricyrtida in which the terminal mouth of the shell is closed by lattice-work, and six or nine lateral apophyses indicate a multiradiate structure. The shell is more or less ovate or spindle-shaped, tapering towards