Page:Scientific results HMS Challenger vol 18 part 2.djvu/361

Rh rows of pores, the upper six rows three to four times as large as the lower six rows. From its upper half diverge almost horizontally three angular club-shaped wings, half as long as the shell.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.06 long, 0.05 broad.

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

2. Peromelissa psilocrana, n. sp.

Shell smooth, very similar to the preceding species in size and form, but differing from it in the disposition of the irregular, roundish pores, which are irregularly scattered, and in the form of the three wings, which are slender, pyramidal, diverging downwards, and about as long as the entire shell.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06 broad.

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

3. Peromelissa capito, Haeckel.

Lithomelissa capito, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 14.

Shell rough, with two joints of nearly equal size and similar ovate form. Pores irregular, roundish, everywhere scattered. From the upper half of the thorax arise three short conical wings, which are little curved and diverge downwards (scarcely half as long as the breadth of the shell).

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06 broad.

Habitat.—Fossil in Barbados.

4. Peromelissa calva, n. sp. (Pl. 57, fig. 12).

Shell rough, with two ovate joints of somewhat different sizes. Pores irregular, roundish, everywhere scattered. Thorax little larger than the cephalis; from its upper half arise three short conical wings, diverging downwardly or nearly horizontally.

Dimensions.—Cephalis 0.06 long, 0.04 broad; thorax 0.07 long, 0.05 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Definition.— (vel Dicyrtida triradiata clausa) with three divergent latticed lateral wings. Cephalis with a horn (or a bunch of horns).

The genus Sethomelissa differs from the nearly allied Micromelissa in the fenestration of the three lateral wings, and may be derived either from this genus by development of lattice-work connecting the three wings with the shell, or perhaps from Clathrocanium by closing the mouth.