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, 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.