Shell subspherical, tuberculate, with a prominent sagittal ring. Pores irregular roundish. Basal plate with three large pores. Feet large, straight, widely divergent, about twice as long as the shell, prismatic, irregularly branched. (Compare the following species.) _Dimensions._--Shell 0.08 in diameter; feet 0.15 long. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms. 7. _Tristylospyris tripodiscium_, n. sp. (Pl. 52, fig. 22). Shell subovate, tuberculate, very similar to the preceding species. It differs from this in the very different size of the irregular pores and the greater breadth of the pedal branches. The basal plate in a complete specimen (observed afterwards from the base) exhibited four large collar pores of the usual form, whilst in the similar preceding species it had three pores. In the similar _Tripodiscium sphærocephalum_ (Pl. 52, fig. 21) the basal mouth is quite simple and open. _Dimensions._--Shell 0.09 long, 0.1 broad; feet 0.12 long. _Habitat._--Central Pacific, Station 268, depth 2900 fathoms. Genus 444. _Cephalospyris_,[62] Haeckel, 1881, Prodromus, p. 441 (_sensu emend._). _Definition._--#Zygospyrida# with three basal feet and two large apical openings or coryphal holes, one on each side of the ring-apex. No true horns. The genus _Cephalospyris_ comprises some few Tripospyrida of very peculiar shape, differing from all other Zygospyrida in the possession of two large apical holes or coryphal apertures, lying on each side of a latticed sagittal septum, which is formed by the upper part of the sagittal ring. The sagittal stricture is deep, with a complete {1035}primary ring. The vertical axis of the slender ovate shell is much greater than the transverse. The network is very delicate, with very small and numerous triangular or polygonal pores. The central capsule encloses peculiar concrements (Pl. 96, fig. 28). 1. _Cephalospyris cancellata_, n. sp. (Pl. 83, fig. 10). Shell slender ovate, two and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous, irregular polygonal pores. The two large apical holes are separated by a latticed triangular sagittal septum, the apex of which represents a rudimentary horn. Basal plate with two large collar holes. Three feet slightly curved, divergent, about half as long as the breadth of the shell; the caudal foot slender, much thinner than the two stout pyramidal pectoral feet. _Dimensions._--Shell 0.32 long, 0.13 broad. _Habitat._--Central Pacific, Station 272, depth 2600 fathoms. 2. _Cephalospyris ovata_, n. sp.