2. Lithopera bursella, Ehrenberg.
Lithopera bursella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 4.
Shell of about the same form and structure as in the nearly allied preceding species, but smaller, of more slender form, with smaller pores and thinner bars. Length of the two joints = 1 : 5, breadth = 1 : 3. In the specimen observed by me the three internal, divergent bars of the ellipsoidal thorax (not seen by Ehrenberg) were as distinct as in the similar preceding and following species.
Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.06 broad.
Habitat.—Indian Ocean, Zanzibar (Pullen), Madagascar (Rabbe), surface.
3. Lithopera ananassa, n. sp. (Pl. 57, fig. 3).
Shell of about the same form and structure as in the two preceding species, but larger and more robust, and differing in the spiny surface. Length of the two joints = 1 : 5, breadth = 1 : 4. Here also the lower half of the spherical cephalis is submerged in the ellipsoidal thorax, and from the collar stricture arise three strong, internal, divergent beams. The bars of the hexagonal pores are much thicker than in the two preceding species.
Dimensions.—Cephalis 0.03 diameter; thorax 0.16 long, 0.12 broad.
Habitat.—Tropical Atlantic, Stations 347 to 352, surface.
4. Lithopera globosa, n. sp.
Cephalis spherical, very small, with two divergent conical horns of half the length; its lower half hidden in the thorax. Length of the two joints = 1 : 5, breadth = 1 : 5. Thorax spherical, with regular, circular, hexagonally-framed pores. From the collar stricture arise three radial internal beams, horizontally diverging, and inserted at the inside of the thorax.
Dimensions.—Cephalis 0.03 diameter; thorax 0.15 diameter.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
5. Lithopera gutta, Ehrenberg.
Shell pear-shaped, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same length; its lower half hidden in the uppermost part of the ovate thorax, and connected with its wall by three internal, cortinar beams. Pores of the thorax very irregular in form and size, partly lobed.
Dimensions.—Cephalis 0.02 diameter; thorax 0.08 long, 0.06 broad.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; Philippine Sea (depth 3300 fathoms), Ehrenberg.
