Dimensions.—Shell 0.16 long, 0.4 broad.
Habitat.—Central Pacific, Station 271, surface.
Genus 516. Cystophormis,[[133]] n. gen.
Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with ovate or urceolate shell and numerous radial ribs in its wall. Mouth more or less constricted, smooth, truncated. Apex without horn.
The genus Cystophormis, like the preceding genera, exhibits numerous prominent radial or longitudinal ribs in the wall of the urceolate shell; it differs from these in the constricted and truncated mouth, with smooth margin of the peristome.
1. Cystophormis pila, n. sp. (Pl. [52], fig. 1).
Shell balloon-shaped, subspherical, with twenty denticulate meridional ribs, alternating with twenty longitudinal rows of circular pores, which are twice as broad as the bars. Peristome constricted and then dilated, smooth, half as broad as the shell.
Dimensions.—Shell 0.11 long, 0.09 broad; mouth 0.06 broad.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
2. Cystophormis ærostatica, n. sp. (Pl. [52], figs. 2, 3).