Dimensions.—Diameter of the phacoid shell 0.08, of the medullary shell 0.04; length of the arms 0.12, basal breadth 0.04, distal breadth 0.08.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
Subgenus 2. Diplactinium, Haeckel.
Definition.—Arms on the distal end armed with a radial terminal spine.
2. Diplactura diploconus, n. sp. (Pl. [38], fig. 5).
Amphiactura diploconus, Haeckel, 1877, MS. et Atlas (pl. xxxviii. fig. 5).
Phacoid shell three times as broad as the medullary shell, with eight pores on its radius, surrounded by a single chambered ring. Arms club-shaped, twice as long as the diameter of the phacoid shell, at the distal end as broad as the latter, at the base only half as broad. Both poles of the common axis of the arms are armed with a strong spindle-shaped terminal spine.
Dimensions.—Diameter of the phacoid shell 0.09, of the medullary shell 0.03; length of the arms (without terminal spines) 0.17, basal breadth 0.05, distal breadth 0.09.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.