Habitat.—Pacific, central area, Stations 270 to 274, depths 2400 to 2800 fathoms; also fossil in Tertiary rocks of Barbados.
3. Trigonactura trigonobrachia, n. sp.
Phacoid shell two and a half times as broad as the medullary shell, with six pores on its radius, without a perfect chambered girdle. Arms nearly equilateral triangular, twice as long as the diameter of the phacoid shell, at the truncated distal end as broad as its diameter and three times as broad as at the narrow base. (Resembles Hymenactura hexagona, but without a patagium.)
Dimensions.—Diameter of the phacoid shell 0.11, of the medullary shell 0.045; length of the arms 0.2, basal breadth 0.035, distal breadth 0.1.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
4. Trigonactura lanceolata, n. sp.
Phacoid shell three times as broad as the medullary shell, with eight pores on its radius, surrounded by one perfect chambered ring. Arms lanceolate, three times as long as the diameter of the phacoid shell, and four times as long as broad in the middle part, at both ends very narrow, blunt.
Dimensions.—Diameter of the phacoid shell 0.09, of the medullary shell 0.03; length of the arms 0.25, breadth in the midst 0.06.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.