_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_. {1087}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. _Dimensions._--Cephalis 0.06 long, 0.08 broad; thorns 0.04 long, 0.06 broad. _Habitat._--Central Pacific, Station 274, depth 2750 fathoms. 3. _Phormospyris trifoliata_, n. sp. Cephalis nut-shaped, with deep sagittal and collar strictures, smaller than the thorax. Mouth of the latter nearly as broad as the cephalis. Pores circular, double-contoured, larger in the thorax than in the cephalis. The thorax has no lateral ribs, but bears around the mouth three large triangular lamellar terminal feet. _Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.06 long, 0.05 broad. _Habitat._--Central Pacific, Station 271, depth 2425 fathoms. Subfamily 2. RHODOSPYRIDA, Haeckel. _Definition._--#Phormospyrida# with a corona of numerous (nine to twelve or more) basal feet. Genus 476. _Patagospyris_,[94] Haeckel, 1881, Prodromus, p. 443. _Definition._--#Phormospyrida# with numerous basal feet (nine to twelve or more) and an apical horn. The genus _Patagospyris_ and the two following closely allied genera differ from the two preceding tripodal genera in the multiplication of the basal feet, and therefore have to the latter the same relation that the Polyspyrida (_Petalospyris_) bear to the Tripospyrida (_Tripospyris_). When the numerous basal feet of _Petalospyris_ become connected by lattice-work, _Patagospyris_ arises. {1088}1. _Patagospyris confluens_, Haeckel. _Petalospyris confluens_, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 5.