Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
Genus 394. Plectophora,[[13]] Haeckel, 1881, Prodromus, p. 424.
Definition.—Plectanida with three radial spines, arising from one common central point and corresponding to the edges of a three-sided pyramid.
The genus Plectophora has been derived from Plagiacantha by union of the meeting neighbouring branches of the three radial spines, and exhibits therefore to it the same relation that Triplecta bears to Triplagia. The loose framework so produced corresponds to the three sides of a flat pyramid and supports the central capsule.
1. Plectophora triomma, n. sp.
Spines equal, straight, three-sided prismatic, thorny, connected by three convex bows, the meeting branches of lateral spines arising in one pair from the middle part of each spine. Therefore the skeleton exhibits three large ovate meshes only.
Dimensions.—Length of the spines 0.12, of the meshes 0.08.
Habitat.—North Pacific, Station 238, surface.
2. Plectophora arachnoides, Haeckel.
Plagiacantha arachnoides, var., Claparède, 1858, Études sur les Infusoires et les Rhizopodes, p. 462, Taf. xxii. fig. 9.