Shell campanulate, smooth, with irregular polygonal pores, very similar to the preceding species but with much broader wings, forming several arcades with three to five rows of irregular meshes. Columella with five or six triradiate verticils of lateral branches. Horn twice as long as the shell, of the same length as the strongly curved spinulate feet. _Dimensions._--Shell 0.09 long, 0.11 broad. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms. 3. _Pteroscenium pinnatum_, n. sp. (Pl. 53, figs. 14, 15, 16). Shell campanulate, smooth, somewhat longer than broad, with irregular delicate network of small roundish pores. Columella straight, with numerous (eight to twelve) triradiate verticils of ascending lateral branches, which are inserted in the shell-wall. The uppermost end of the columella is a conical apical horn. The three divergent feet are smooth, slender, conical, slightly curved, about as long as the shell, pinnate, with six to ten pairs of ascending lateral branches, parallel to those of the columella and inserted on the three vaulted lateral wings. (Fig. 14 exhibits the outside of the shell, fig. 15 the internal structure of the cortina, fig. 16 the basal view.) _Dimensions._--Shell 0.1 long, 0.12 broad. _Habitat._--Central Pacific, Station 274, depth 2750 fathoms. 4. _Pteroscenium spinulosum_, n. sp. Shell campanulate, spinulate, about as long as broad, with small and numerous irregular polygonal pores, very similar to the preceding species, but differing in the more slender form of {1153}the horn and the feet, bearing more numerous lateral branches (twelve to sixteen pairs on each foot). Columella with six to eight triradiate verticils. Horn about as long as the shell. _Dimensions._--Shell 0.1 long, 0.1 broad. _Habitat._--Central Pacific, Station 268, depth 2900 fathoms. 5. _Pteroscenium macropodium_, n. sp. Shell campanulate, spinulate, with irregular polygonal pores; very similar to the two preceding species, but differing in the size and shape of the three feet, which are for the most part solid, triangular, nearly parallel, vertical, very slender, three times as long as the shell, latticed only at the curved base, with few pairs of lateral branches. Columella with four to six triradiate verticils, as long as the stout triangular pyramidal horn. _Dimensions._--Shell 0.1 long, 0.08 broad. _Habitat._--Central Pacific, Station 272, depth 2600 fathoms. 6. _Pteroscenium tripocolpum_, n. sp.