Habitat.—North Pacific, Station 244, surface.
Genus 475. Phormospyris,[[93]] Haeckel, 1881, Prodromus, p. 442 (sensu emendato).
Definition.—Phormospyrida with three basal feet, without apical horn.
The genus Phormospyris has been derived from Acrospyris, its ancestral form, by reduction and loss of the apical horn; it therefore bears to the latter the same relation that Tristylospyris has to the ancestral Tripospyris.
1. Phormospyris tricostata, n. sp. (Pl. [83], fig. 15).
Cephalis nut-shaped, thorny, with deep sagittal and collar strictures, half as large as the pyramidal thorax. Mouth of the latter dilated and ciliated, twice as broad as the cephalis. Pores irregular, polygonal, with thin bars. Three cylindrical, straight, divergent ribs descend in the wall of the thorax, and are prolonged over the mouth into three short conical teeth.
Dimensions.—Cephalis 0.06 long, 0.09 broad; thorns 0.08 long, 0.16 broad.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Phormospyris tridentata, n. sp. (Pl. [95], fig. 18).
Cephalis nut-shaped, with deep sagittal and collar strictures, about twice as large as the thorax. Mouth of the latter half as broad as the cephalis. Pores very small and numerous, subregular, circular. Collar plate with four large triangular pores. In the wall of the thorax three vertical prismatic ribs descend, which are prolonged over the mouth into three parallel feet of the same length.