Habitat.—Fossil in Barbados.
3. Theopera fusiformis (Pl. [67], fig. 5).
Shell nearly spindle-shaped, rough, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 4. Cephalis hemispherical, large, with an oblique conical horn of the same length. Thorax hemispherical; abdomen inversely conical. Pores irregular, roundish, of very different sizes. Three wings short, broad, diverging, triangular, and striated, embracing at the base the lumbar stricture, the lower third of the thorax and the upper third of the abdomen.
Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.12; breadth, a 0.045, b 0.1, c 0.08.
Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.
4. Theopera luscinia, Haeckel.
Lithornithium luscinia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 9.
Shell slenderly ovate, with distinct collar, but indistinct lumbar strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 5 : 5. Cephalis hemispherical, with a slender cylindrical horn of three times the length, bearing a spindle-shaped spinulate top (like a fir-cone). Pores subregular, circular, twice as broad in the abdomen as in the thorax. Three wings arising with broad triangular base, embracing the lower third of the thorax and the upper third of the abdomen, prolonged into three slender diverging spines, as long as the shell.
Dimensions.—Length of the three joints a 0.015, b 0.05, c 0.1; breadth, a 0.02, b 0.07, c 0.07.
Habitat.—Fossil in Barbados.