Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.03 long, 0.05 broad.
Habitat.—Western Tropical Pacific, Stations 200 to 225, surface.
2. Psilomelissa phalacra, n. sp.
Shell smooth, with deep collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 4. Cephalis ovate, hyaline, with few small pores only in the lower third. Thorax cylindrical, truncate, with small irregular, roundish pores. From its upper third there arise below the stricture three club-shaped, nearly horizontally divergent wings, as long as the thorax. The cephalis and the three feet are similar to those of Peromelissa phalacra, (Pl. [57], fig. 11); but the cylindrical thorax with irregularly scattered pores is completely different, and exhibits a truncate, wide open mouth.
Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.04 broad.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
3. Psilomelissa hertwigii, Haeckel.
Lithomelissa hertwigii, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 517, Taf xxxiii. fig. 22, a, b.
Shell rough, with obliterated collar stricture. Length of the two joints = 4 : 4, breadth = 5 : 5. Cephalis hemispherical. Thorax little larger, cylindrical. From its upper half there arise three very strong pyramidal divergent wings, about as long as the shell. Pores of both joints very small and numerous, circular. Mouth truncate, wide open.
Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.04 long, 0.05 broad.