_Dimensions._--Shell 0.1 long, 0.13 broad; horn and feet 0.06 long. _Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface. 15. _Tripospyris tribrachiata_, Haeckel. _Cladospyris tribrachiata_, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xxi. fig. 8. Shell subspherical, smooth, with slight sagittal stricture and numerous, very small circular pores. Basal plate with numerous small pores. Apical horn and the three divergent feet very large and stout, straight, three-sided prismatic, with dentate edges, two to three times as long as the shell. _Dimensions._--Shell diameter 0.05; horn and feet 0.1 to 0.15 long. _Habitat._--Fossil in Barbados. 16. _Tripospyris furcata_, n. sp. (Pl. 83, fig. 11). Shell nut-shaped, smooth, with deep sagittal stricture and broad ring. Basal plate with three pairs of small pores. Facial and occipital plates each with a pair of very large holes. Apical horn and caudal foot simple conical, two pectoral feet forked or irregularly branched. _Dimensions._--Shell 0.08 long, 0.12 broad; horn and feet 0.05 long. _Habitat._--Central Pacific, Station 271, depth 2425 fathoms. Genus 442. _Triceraspyris_,[60] Haeckel, 1881, Prodromus, p. 441. _Definition._--#Zygospyrida# with three basal feet and three coryphal horns. The genus _Triceraspyris_ has arisen from the preceding ancestral _Tripospyris_ by the development of two paired frontal horns, so that the shell here bears six appendages, {1030}three superior or coryphal spines and three inferior or basal spines; two of these are odd and dorsal (the apical horn and the caudal foot), the four others are paired and ventral (the frontal horns and the pectoral feet). The numerous species of this genus may be divided into three subgenera, according to the simple or branched shape of the ascending horns and of the descending feet. Subgenus 1. _Triospyris_, Haeckel, 1881, Prodromus, p. 441. _Definition._--Horns and feet simple, not branched nor forked. 1. _Triceraspyris tripodiscus_, n. sp. Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish, two pairs of larger pores on each side of the ring. Basal plate with three large pores. Horns and feet slender cylindrical, straight, divergent; three horns about as long as the shell, three feet twice as long. _Dimensions._--Shell 0.06 long, 0.08 broad; horn 0.05 long, feet 0.1. _Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms. 2. _Triceraspyris cortiniscus_, n. sp. Shell subspherical, smooth, with slight sagittal stricture. Pores small and numerous, subregular roundish. Basal plate with two large pores (?). Apical horn conical, short, half as long as the shell and the two lateral horns, which are curved outwards. All three feet equal, cylindrical, strongly curved and divergent, twice to three times as long as the shell. _Dimensions._--Shell 0.07 long, 0.08 broad; horn 0.04 to 0.08 long, feet 0.15 to 0.2 long.