3. Plectanium sphærozoum, n. sp.
Spines straight, cylindrical, ten to twelve times as long as the common middle rod, with six to eight verticils of thorny branches, tapering towards the distal end; the branches of the verticils are simple in the distal half, again ramified in the basal half, and here connected together by irregularly branched threads forming a loose framework. (Resembles one spiculum of Sphærozoum verticillatum, Pl. [4], fig. 7, but is more richly branched, with united ramules.)
Dimensions.—Length of the spines 0.2, of the middle rod 0.01.
Habitat.—Central Pacific, Station 266, surface.
Subfamily 4. Polyplectida, Haeckel, 1881, Prodromus, p. 424.
Definition.—Plectanida with numerous (seven to nine or more) radial spines.
Genus 400. Polyplecta,[[19]] Haeckel.
Definition.—Plectanida with numerous (seven to nine or more) radial spines, arising from a common centre and lying in different planes.
The genus Polyplecta comprises provisionally all Plectanida possessing seven or more radial spines, united in the centre of the framework. It may be derived from Polyplagia by meeting and concrescence of the free branches. But as in the latter genus, here also the few observed species are very different, perhaps of different origin, and may be afterwards better separated as representatives of diverse genera.
1. Polyplecta heptacantha, n. sp. (Pl. [91], fig. 12).