Shell tuberculate, with distinct collar and deep sagittal stricture. Cephalis nut-shaped, with numerous irregular, roundish pores; three pairs of larger annular pores on each side of the ring. Basal plate with four larger pores (two major cardinal and two minor jugular pores). Apical horn slender, pyramidal, curved, about as long as the shell, with three recurved short spines. Thorax three-sided, about twice as large as the cephalis, with three large basal holes and a broad riband with numerous smaller holes; three ribs between them stout, pyramidal, strongly curved, prolonged into three convergent crescentic feet. _Dimensions._--Cephalis 0.08 long, 0.11 broad; thorax 0.14 long, 0.16 broad. _Habitat._--Central Pacific, Station 271, depth 2425 fathoms. 2. _Acrospyris dictyophimus_, n. sp. Shell smooth. Cephalis and thorax of nearly the same structure and form as in the preceding species; it differs from the latter in the shape of the three stout basal feet, which are {1086}straight, much longer than the thorax, divergent, and at the broader base irregularly fenestrated, without three larger holes. _Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.07 long, 0.12 broad. _Habitat._--North Pacific, Station 241, depth 2300 fathoms. 3. _Acrospyris pyramidalis_, n. sp. Shell three-sided pyramidal, with slight collar stricture. Cephalis campanulate, with deep sagittal stricture and stout ring, armed with a strong pyramidal horn of the same length. Thorax shorter and broader, truncate. Pores irregular, roundish, scarce. Three feet divergent, three-sided pyramidal, as long as the cephalis. _Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.02 long, 0.08 broad. _Habitat._--Fossil in Barbados. 4. _Acrospyris macrocephala_, n. sp. Shell spinulate, with deep sagittal and very deep collar stricture. Cephalis very large, nut-shaped, twice as long and broad as the small, truncate, pyramidal thorax. Pores irregular, roundish. Horn spindle-shaped, nearly as long as the cephalis; the three divergent feet are of the same form and size as the horn, and arise as three ribs from the deep collar stricture. _Dimensions._--Cephalis 0.1 long, 0.15 broad; thorax 0.05 long, 0.09 broad. _Habitat._--Fossil in Barbados. 5. _Acrospyris fragilis_, n. sp. Shell very thin-walled and fragile, with deep sagittal and collar strictures. Pores very small and numerous, circular. Cephalis nut-shaped, nearly spherical, with a slender bristle-shaped horn of the same length. Basal stricture with two large collar pores only (luminella). Thorax nearly three-sided prismatic, longer than the cephalis, with three parallel ribs, prolonged into three slender, long, bristle-shaped feet. _Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.08 long, 0.06 broad. _Habitat._--North Pacific, Station 244, surface. Genus 475. _Phormospyris_,[93] Haeckel, 1881, Prodromus, p. 442 (_sensu emendato_).