Shell irregular polyhedral, with ten to fifteen polygonal faces and rounded edges. Pores very small, circular, irregularly scattered, smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. On the inside of every shell-face one short, nearly cylindrical, centripetal tubule, twice as long as broad, and about one-third as long as the shell radius. Outer umbilical mouth of the tubules somewhat wider than the inner truncated mouth.
Dimensions.—Diameter of the shell 0.11 to 0.12, of the pores 0.003 to 0.005, of the bars 0.01 to 0.02; length of the inner tubuli 0.02, breadth of them 0.01.
Habitat.—South Pacific, Station 288, depth 2600 fathoms.
Genus 32. Buccinosphæra,[[54]] n. gen.
Definition.—Collosphærida with simple shells, having on the inside radial centripetal tubes, the walls of which are fenestrated.
The genus Buccinosphæra exhibits, on the inner surface of the shell, radial centripetal tubules similar to those of the foregoing Pharyngosphæra; but the walls of these tubes are here latticed, not solid; they represent therefore true invaginations of the whole shell-wall.
1. Buccinosphæra invaginata, n. sp. (Pl. [5], fig. 11).
Shell irregular roundish or nearly polyhedral, with a variable number of umbilical depressions, which are prolonged on the inside into cylindrical or somewhat conical, centripetal, fenestrated tubes, about one-third as long as the shell radius. Inner mouth of the tubes narrower, scarcely half as broad as the outer mouth, about equal to one-fourth the shell radius, truncated. Pores of the tubes and of the shell small, roundish, irregular in size and distribution, about as broad as the bars. Twenty-five to thirty pores in the half meridian of the shell. In all observed specimens the spherical central capsule (half as broad as the shell) contained a large number of crystals.
Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.003, of the bars 0.002 to 0.003; length of the tubuli 0.02; outer mouth 0.026, inner mouth 0.013; crystals in the central capsule 0.002 to 0.004, sometimes 0.008.
Habitat.—Philippine Islands (Samboangan), Station 213, surface.