Shell nut-shaped, smooth, with deep sagittal stricture. Cephalis on the lateral sides with numerous small roundish pores, on each side of the ring with a pair of very large holes. Basal plate with two large collar pores. Cupola flat, cap-shaped, with two large parietal pores above the ring. Coronet with eight conical, slightly divergent feet, about one-fourth as long as the shell. _Dimensions._--Shell 0.08 long, 0.1 broad; ring 0.06 long; feet 0.02 long. _Habitat._--North Pacific, Station 244, depth 2900 fathoms. 2. _Tiarospyris galea_, n. sp. Shell helmet-shaped, with deep sagittal stricture. Cephalis with irregular, polygonal pores; on each side of the ring two pairs of larger annular pores. Basal plate with four large pores. Cupola high, conical, nearly as long as the cephalis, separated from it by a distinct coronal stricture. Basal coronet with twelve to sixteen slender curved divergent feet, nearly as long as the shell. _Dimensions._--Shell 0.16 long, 0.12 broad; ring 0.1 long; feet 0.15 long. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms. 3. _Tiarospyris mitra_, n. sp. (Pl. 87, figs. 9, 10). Shell subspherical, smooth. Cephalis on the lateral sides with small roundish, double-contoured pores, on each side of the ring with three to five pairs of larger pores, each of which is closed by a thin fenestrated lamella (different on the frontal face, fig. 9, and the dorsal face, fig. 10). Cupola flat, cap-shaped, separated by a distinct coronal stricture, with similar pores. Basal coronet with, ten to twelve short conical convergent feet. _Dimensions._--Shell 0.11 long, 0.12 broad; ring 0.04 long; feet 0.02 long. _Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms. {1083}4. _Tiarospyris amphora_, n. sp. (Pl. 87, fig. 8). Shell amphora-shaped, in the upper half smooth, in the lower spiny, without external sagittal stricture. Cephalis subspherical with a small number of irregular, large, roundish pores, which are closed by a thin fenestrated lamella. Cupola flat, cap-shaped, with numerous small pores. Base covered with numerous conical divergent feet of different sizes, the largest one-third as long as the shell. Internal sagittal ring ovate, nearly free. _Dimensions._--Shell 0.14 long, 0.13 broad; ring 0.1 long; feet 0.04 long. _Habitat._--South Pacific, Station 285, depth 2375 fathoms. Genus 473. _Pylospyris_,[91] Haeckel, 1881 Prodromus, p. 443. _Definition._--#Tholospyrida# without basal feet, with an apical horn. The genus _Pylospyris_ was first known from a Mediterranean species, called by me, in 1862, _Spyridobotrys trinacria_. As this name was given erroneously, on the supposition of a near relation to the Botryodea (= Polycyrtida), I changed it afterwards to _Pylospyris_. This genus differs from the other Tholospyrida in the total absence of basal feet, and may therefore be derived either from them by reduction of the feet, or from _Dictyospyris_ by formation of a galea.