Page:Scientific results HMS Challenger vol 18 part 2.djvu/458

1334 shell; three edges of the horn wing-shaped and dentated. Thorax hemispherical, in the middle zone with three conical wings, which are half as long as the thorax, and curved downwards. Pores hexagonal, roundish, twice as broad in the inflated abdomen as in the thorax. Mouth constricted, with a corona of from fifteen to eighteen conical, divergent, curved feet, similar to the thoracic wings.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.025, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Pterocodon favosus, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 2 : 4 : 4. Cephalis hemispherical, with a conical horn of twice the length. Three wings of the thorax equal to those of the preceding species. Pores regular, circular, hexagonally framed, of equal size in the thorax and abdomen. Mouth constricted, with a corona of nine straight, conical, nearly vertical feet.

Dimensions.—Length of the three joints, a 0.0025, b 0.05, c 0.05; breadth, a 0.05, b 0.09, c 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Definition.— (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the thorax, and numerous latticed terminal feet around the mouth of the abdomen.

The genus Dictyocodon, one of the most elegant among the, differs from the preceding Pterocodon in the fenestration of the three lateral wings of the thorax, and the numerous terminal feet of the abdomen. It may be derived from Dictyoceras by development of regular lattice-feet around the terminal mouth.

Definition.—The three lateral lattice-wings arise from the thorax alone.

1. Dictyocodon annasethe, n. sp. (Pl. 71, fig. 11).

Shell with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with a very large, three-sided prismatic horn of three times the length, bearing at the base some smaller accessory spines. Thorax nearly conical, with three large, inflated, triangular lattice-wings, the upper edge of which (the cortinar rod) descends obliquely, and is larger