_Cyrtocalpis urna_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 7. Shell smooth, urceolate, with subregular, circular pores of different sizes, gradually increasing towards the mouth, of about the same breadth as the bars. Mouth without peristome (?), about half as broad as the shell. _Dimensions._--Shell 0.09 long, 0.06 broad; mouth 0.035 broad. _Habitat._--Fossil in tertiary rocks of Sicily (Grotte). {1187}5. _Cyrtocalpis sethopora_, n. sp. (Pl. 52, fig. 4). Shell smooth, urceolate, very thin-walled, with large irregular roundish meshes, each of which is closed by a thin porous sieve-plate. Mouth two-thirds as broad as the shell, with a broad, emarginate, longitudinally striped peristome. (Perhaps the shell of a Tintinnoid Infusorium?) _Dimensions._--Shell 0.08 long, 0.05 broad; mouth 0.03 broad. _Habitat._--Central Pacific, Station 272, depth 2600 fathoms. 6. _Cyrtocalpis compacta_, n. sp. (Pl. 52, figs. 7, 8). Shell smooth, ovate, very thick-walled, with small, subregular, circular pores of equal size, perpendicularly perforating the wall, about half as broad as the bars. Mouth small, only one-third as broad as the compact shell. (Perhaps a reduced _Lithocampe_ or _Lithomitra_?) _Dimensions._--Shell 0.08 long, 0.04 broad; mouth 0.015 broad. _Habitat._--Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados. 7. _Cyrtocalpis lithomitra_, n. sp. (Pl. 52, figs. 5, 6). Shell smooth, slender, ovate, nearly cylindrical, with small subregular, circular pores, which are disposed in nine to twelve transverse rows, and obliquely ascending perforate the wall. Mouth wide, without peristome, about two-thirds as broad as the shell. (Compare _Lithomitra_, Pl. 79.) _Dimensions._--Shell 0.09 long, 0.045 broad; mouth 0.03 broad. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados. 8. _Cyrtocalpis ovulum_, n. sp. _Cyrtocalpis obliqua_, var. _ovulum_, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. fig. 3. Shell smooth, broad, ovate, with very numerous and small regular circular pores, quincuncially disposed, twice as broad as the bars. Mouth without peristome, about half as broad as the shell. _Dimensions._--Shell 0.09 long, 0.047 broad; mouth 0.04 broad. _Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface. 9. _Cyrtocalpis obliqua_, Haeckel. _Cyrtocalpis obliqua_, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. figs. 4-11. Shell smooth, irregularly ovate, more or less oblique, variable in size and form, sometimes nearly spherical, at other times subcylindrical. Pores subregular, circular, once or twice the breadth of the bars. Mouth simple without peristome, about half as broad as the shell. _Dimensions._--Shell 0.07 to 0.1 long, 0.05 to 0.08 broad; mouth 0.03 to 0.04 broad. _Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface. {1188}10. _Cyrtocalpis gromia_, n. sp. (Pl. 51, fig. 11).