Shell cup-shaped or campanulate, with six prominent ribs, prolonged into six terminal triangular feet, one-third as long as the shell. Ribs connected by five or six transverse horizontal rings; meshes between them rounded squarish. (As Ehrenberg has given no figure of this species, its identity with the Challenger specimen is doubtful.) _Dimensions._--Shell 0.08 long, 0.06 broad; mouth 0.04 broad. _Habitat._--North Atlantic, Station 353, depth 2965 fathoms. {1168}2. _Archiphormis campanulata_, n. sp. Shell campanulate, with nine prominent denticulate ribs, prolonged into nine terminal feet, which are broad, lamellar, truncate, nearly vertical, one-third as long as the shell. Pores between the ribs circular, disposed in nine longitudinal and seven to eight transverse rows. _Dimensions._--Shell 0.09 long, 0.1 broad; mouth 0.06 broad. _Habitat._--Central Pacific, Station 270, depth 2925 fathoms. 3. _Archiphormis urceolata_, n. sp. (Pl. 98, fig. 11). Shell urceolate, with nine smooth prominent curved ribs, prolonged into nine triangular convergent short feet, scarcely one-sixth as long as the shell. Pores between the ribs in nine regular longitudinal rows, twice or three times as broad as long, quadrangular, eight to twelve pores in each row. Mouth constricted, half as broad as the shell. _Dimensions._--Shell 0.13 long, 0.11 broad; mouth 0.06 broad. _Habitat._--Central Pacific, Station 266, depth 2750 fathoms. Genus 519. _Halicalyptra_,[136] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54 (_sensu emendato_). _Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) without radial ribs in the wall of the campanulate or ovate shell. Mouth with a coronet of radial feet. Apex with a horn. The genus _Halicalyptra_ and the two following closely allied genera differ from the preceding Archiphormida in the absence of radial ribs. The multiradiate structure is indicated only by the terminal spines or feet, forming a coronet around the mouth. These feet are either the free ends of reduced ribs, or new productions of the peristome. _Halicalyptra_ may be derived from _Calpophæna_ and _Petalospyris_ by loss of the basal lattice-plate of the cephalis. But it is also possible that it has been derived from _Anthocyrtis_ by loss of the cephalis, and that its shell corresponds to the thorax of the latter. Subgenus 1. _Acrocalpis_, Haeckel, 1881, Prodromus, p. 427. _Definition._--Shell smooth, without spines or thorns (other than the feet and the apical horn). {1169}1. _Halicalyptra virginica_, Ehrenberg. _Halicalyptra virginica_, Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig. 110. _Halicalyptra virginica_, Haeckel, 1862, Monogr. d. Radiol., p. 289. _Haliomma virginicum_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 71. _Acrocalpis virginica_, Haeckel, 1881, Prodromus, p. 427.