Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.
Subgenus Hexalastromma, Haeckel.
Definition.—Arms more or less different in size or form; shell bilateral.
3. Hexalastrum orchidaceum, n. sp. (Pl. [44], fig. 5).
Hexactura orchidacea, Haeckel, 1881, Prodromus, p. 459.
Arms different in length, so that two unequal opposite odd arms determine the main axis, and the four other arms lie on both sides of this as two different pairs. The proportion of their relative length is the following:—anterior lateral arms five, anterior odd arm six; posterior lateral arms seven, posterior odd arm eight. Each arm is club-shaped, two to three times as long as broad, and divided into six to eight joints by five to seven transverse septa; its distal end is armed with a terminal spine and twice as broad as its base.
Dimensions.—Radius of the posterior odd arm 0.4, of the anterior odd arm 0.3; of the posterior lateral pair 0.35, of the anterior lateral pair 0.25; basal breadth 0.08, distal breadth 0.16.
Habitat.—Pacific, central area, Station 266, depth 2750 fathoms.
Genus 244. Hexinastrum,[[283]] Haeckel, 1881, Prodromus, p. 461.
Definition.—Porodiscida with six simple, undivided, chambered arms, connected by a patagium.