1. _Cladarachnium ramosum_, n. sp. (Pl. 55, figs. 5, 6). Shell flatly conical or tent-shaped, with nearly straight lateral outlines; apical part somewhat higher. Apex with three cortinar pores surrounded by a few girdles of larger pores. From these there arise about twelve to fifteen strong radial beams at unequal distances; these are somewhat curved and irregularly branched. The network between them has irregular polygonal meshes and is more delicate towards the periphery. Margin with twenty-four to thirty irregular indentations or concave excisions, separated by the prominent distal ends of the branched ribs. _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. {1166}2. _Cystophormis ærostatica_, n. sp. (Pl. 52, figs. 2, 3). Shell balloon-shaped, subspherical, with twenty smooth meridional ribs, alternating with twenty longitudinal rows of circular pores, of the same breadth as the bars. Peristome constricted, about half as broad as the shell. _Dimensions._--Shell 0.09 long, 0.07 broad; mouth 0.03 broad. _Habitat._--Central Pacific, Station 266, depth 2750 fathoms. 3. _Cystophormis spiralis_, n. sp. (Pl. 51, fig. 9). Shell ovate, one and a half times as long as broad, with twenty spirally convoluted, elegantly denticulated ribs, alternating with twenty spiral rows of small circular pores, of about the same breadth as the bars. Peristome constricted, very small, only one-seventh as broad as the shell. _Dimensions._--Shell 0.1 long, 0.07 broad; mouth 0.01 broad. _Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms. 4. _Cystophormis tabulata_ (Pl. 79, fig. 2). Shell urceolate and tabulate, twice as long as broad with twenty-five to thirty denticulated longitudinal ribs crossed by twenty to twenty-four transverse rings. Pores therefore regularly disposed in longitudinal and transverse rows; each pore circular, with a square frame. Peristome constricted, scarcely half as broad as the shell. _Dimensions._--Shell 0.2 long, 0.1 broad; mouth 0.04 broad.