Habitat.—Fossil in Barbados.
4. Psilomelissa calvata, n. sp. (Pl. [56], fig. 3).
Shell smooth, with sharp collar stricture. Length of the two joints = 7 : 5, breadth = 5 : 6. Cephalis ovate, large, with subregular, circular, double-contoured pores. Thorax smaller, ovate, with very irregular, roundish pores of different sizes. From its upper third there arise three conical, slender, widely divergent spines or wings of the same length. (In fig. 3 the cephalis with the three wings is alone represented.)
Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.05 long, 0.06 broad.
Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.
5. Psilomelissa sphærocephala, n. sp.
Shell rough, with deep collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis spherical. Thorax cap-shaped, flat and broad. From its upper half there arise three pyramidal wings, half as long, fenestrated at the base and nearly horizontally divergent. Mouth constricted, half as broad as the thorax.
Dimensions.—Cephalis 0.03 diameter; thorax 0.06 long, 0.09 broad.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.