Shell rough, thick-walled, ovate. Pores large, subregular, circular, twice to four times as broad as the bars. Horn small, conical, not larger than one pore. Mouth very small, truncate, scarcely larger than one pore.
Dimensions.—Shell 0.1 long, 0.07 broad; horn 0.012, mouth 0.015.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
4. Archicorys globosa, n. sp.
Shell nearly spherical, thorny, thick-walled. Pores very large, circular, separated by spinulate frames, smaller towards each pole. Horn conical, large, nearly as long as the radius of the shell; mouth truncate, simple, about one-third as broad as the shell.
Dimensions.—Shell diameter 0.13, horn 0.06, mouth 0.04.
Habitat.—Fossil in Barbados.
5. Archicorys ovata, n. sp. (Pl. [51], fig. 10).
Shell ovate, rough, thick-walled. Pores regular, circular, of equal size, very small and numerous, quincuncially disposed. Horn small, conical, sometimes (as in the figured specimen) rudimentary. When it becomes lost, the species may be called Cyrtocalpis ovata. Mouth truncate, small, simple, one-sixth as broad as the shell.
Dimensions.—Shell 0.2 long, 0.15 broad; horn 0.01 to 0.03 long, mouth 0.03 broad.