Phacoid shell three times as broad as the medullary shell, with nine pores on its radius. Arms club-shaped, one and a half times as long as the diameter of the phacoid shell, in the distal part nearly as broad as the latter, in the basal part one-third as broad; at the end a strong pyramidal spine. Patagium nearly complete, with concave dentated margin between each pair of arms, therefore the pentagonal disk of the whole shell with concave sides.
Dimensions.—Diameter of the phacoid shell 0.12, of the medullary shell 0.04; length of the arms (without terminal spine) 0.18, basal breadth 0.04, distal breadth 0.1.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
Family XXI. Porodiscida, Haeckel (Pls. [41]-[47]).
Porodiscida, Haeckel, 1881, Prodromus, p. 459.
Trematodiscida et Discospirida, Haeckel, 1862, Monogr. d. Radiol.,
pp. 485, 491, 513.
Calodictya, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss.
Berlin, p. 53 (partim).
Definition.—Discoidea without phacoid shell, with flat discoidal shell, in which a simple spherical central chamber is surrounded by concentric chambered rings (each ring divided by radial beams into imperfect chambers). Surface of the disk on the two flat sides covered by a porous sieve-plate.