The genus Trypanosphæra is intermediate between Siphonosphæra and Chœnicosphæra agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a coronal of teeth on their outer opening.
Subgenus 1. Trypanosphærula, Haeckel.
Definition.—All pores of the shell prolonged into short coronated tubules.
1. Trypanosphæra trepanata, n. sp. (Pl. [5], fig. 4).
Shell regular spherical, with regular circular pores of nearly equal size, at unequal distances, one to four times as broad as the bars. Eight to ten pores on the half meridian. All the pores prolonged into short cylindrical tubuli about as long as broad, armed on the external mouth with an elegant coronal of twenty to thirty straight bristle-shaped, parallel teeth.
Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.015 to 0.02; length of the tubuli 0.02.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
2. Trypanosphæra dentata, n. sp.
Shell regular spherical, with regular circular pores of equal size, but at very different distances. Only three to four pores on the half meridian. All the pores prolonged into irregular curved, cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve short conical teeth on the distal end.
Dimensions.—Diameter of the shell 0.08 to 0.09; length of the tubuli 0.04, breadth 0.02.