Shell helmet-shaped, smooth, with deep sagittal stricture. Cephalis nearly spherical, with irregularly polygonal pores; four or five pairs of larger annular pores on each side of the strong angular ring. Cupola flat, conical, with two pairs of larger pores. Columella enclosed in its dorsal wall, {1080}bearing an irregularly branched horn. Caudal foot short conical, simple. Two pectoral feet half as long as the shell, angular, subvertical, irregularly branched. _Dimensions._--Shell 0.15 diameter, ring 0.1 long, pectoral feet 0.07 long. _Habitat._--Central Pacific, Station 271, depth 2425 fathoms. 5. _Tholospyris cupola_, n. sp. (Pl. 89, fig. 4). Shell pear-shaped or cupola-shaped, smooth, with slight sagittal stricture. Cephalis not distinctly separated from the galea, as the ring in the uppermost part of the shell-wall becomes obliterated. Pores irregularly polygonal, small and numerous. Basal plate with four large pores. Apical horn and the three divergent feet, irregularly branched; feet nearly as long as the shell, about four times as long as the horn. _Dimensions._--Shell 0.14 diameter, ring 0.1 long, feet 0.12 long. _Habitat._--Central Pacific, Station 274, depth 2750 fathoms. Genus 470. _Lophospyris_,[88] Haeckel, 1881, Prodromus, p. 443 (_sensu emendato_). _Definition._--#Tholospyrida# with two lateral basal feet and an apical horn. The genus _Lophospyris_ differs from the preceding _Tholospyris_, its probable ancestral form, in the absence of the caudal foot, and therefore bears to it the same relation that _Dipospyris_ does to _Tripospyris_. The two pectoral feet are alone developed and are placed opposite in the frontal plane. _Lophospyris_ may also be derived from _Dipospyris_ by the formation of a galea. 1. _Lophospyris dipodiscus_, n. sp. (Pl. 95, fig. 14). Shell ovate, spinulate, with sharp transverse coronal constriction. Cupola hemispherical, half as large as the nut-shaped cephalis. Pores irregularly roundish, much larger on the sagittal constriction. Apical horn pyramidal, about half as long as the shell. Two lateral feet cylindrical, strongly curved, about as long as the shell, with some irregular branches; together forming a nearly complete circle. _Dimensions._--Shell 0.09 long, 0.08 broad; ring 0.04 long, feet 0.08 long. _Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms. 2. _Lophospyris acuminata_, Haeckel. _Ceratospyris acuminata_, R. Hertwig, 1879, Organism. d. Radiol., p. 70, Taf. vii. fig. 2. Shell campanulate, smooth, without external transverse stricture. Cupola conical, half as long and broad as the nut-shaped cephalis. Pores irregularly roundish, on each side of the sagittal {1081}strictures much larger. Basal plate with four large triangular pores. Apical horn slender, prismatic; its outer free part of the same length as the inner columella, and as the two lateral feet, which are curved, shorter than half the ring.