2. Triplagia triradialis, n. sp.
Spines straight, of equal size and similar form, equidistant, three-sided prismatic, regularly pinnate, with six pairs of opposite pinnulæ, tapering gradually towards the distal ends; the basal pinnulæ are again branched, with straight ramules.
Dimensions.—Length of each spine 0.27, of the basal branches 0.08.
Habitat.—North Pacific, Station 256, surface.
3. Triplagia horizontalis, n. sp.
Spines curved, cylindrical, irregularly branched, with three primary and nine to twelve secondary branches, which are also slightly curved. The angles between the bases of the three spines are equal, but the size and form of the branches different.
Dimensions.—Length of the three spines 0.15 to 0.25, of the basal branches 0.05 to 0.08.
Habitat.—West Tropical Pacific, Station 226, depth 4475 fathoms.
Genus 385. Plagiacantha,[[4]] Claparède, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, November 13.
Definition.—Plagonida with three radial spines, arising from one common central point and corresponding to the edges of a three-sided pyramid.