1. Lithomelissa macroptera, Ehrenberg.
Shell smooth, with distinct collar stricture. Relative length of the two joints = 4 : 5, breadth = 3 : 4. Cephalis ovate, with a stout, excentric, vertical, pyramidal horn of the same length. Thorax little larger, ovate, truncate. Both joints with very small and scattered pores. Three divergent ribs arise from the base of the cephalic horn, and are prolonged over the major part of the thorax; their under free part arises from the middle part of the thorax and is as long as the horn, straight, pyramidal. Mouth truncate, little constricted.
Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.05 long, 0.04 broad.
Habitat.—Fossil in Barbados.
2. Lithomelissa ehrenbergii, Bütschli.
Lithomelissa macroptera, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 8.
(?) Lophophæna capito, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 6.
(?) Lophophæna galeata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 12.Shell rough, with distinct collar stricture. Relative length of the two joints = 4 : 2, breadth = 3 : 4. Cephalis ovate, with a stout excentric, oblique, pyramidal horn of half the length. Thorax little shorter, truncate, conical. Both joints with regular circular pores, of the same breadth as the bars. Three divergent conical feet, as long as the cephalis, arise below the collar stricture. Mouth truncate, not constricted.
Dimensions.—Cephalis 0.08 long, 0.06 broad; thorax 0.04 long, 0.08 broad.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms; fossil in Barbados.
3. Lithomelissa macroceras, n. sp.
Shell spiny, with sharp collar stricture. Relative length of the two joints = 5 : 7, breadth = 5 : 6. Cephalis spherical, with a large pyramidal horn of twice the length. Thorax little longer, ovate, truncate. Both joints with regular circular pores, three times as broad as the bars. Three divergent pyramidal feet, twice as long as the cephalis, arise from the middle part of the thorax. Mouth constricted, half as broad as the thorax.
Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.07 long, 0.06 broad.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
4. Lithomelissa mitra, Bütschli.
Shell smooth, with distinct collar stricture. Relative length of the two joints = 5 : 4, breadth = 4 : 5. Cephalis ovate, with a slender, straight, vertical, pyramidal horn of the same length. Thorax ovate,
