Spines straight and stout, three-sided prismatic, smooth, ten to twelve times as long as the middle rod; each on the distal end cleft into three divergent straight branches, which are again trichotomous. _Dimensions._--Length of the spines 0.15 to 0.18, of the middle rod 0.015. _Habitat._--South Pacific, Station 288, surface. Subfamily 4. POLYPLAGIDA, Haeckel, 1881, Prodromus, p. 424. _Definition._--#Plagonida# with numerous (seven to nine or more) radial spines. Genus 392. _Polyplagia_,[11] n. gen. _Definition._--#Plagonida# with numerous (seven to nine or more) radial spines, arising from a common centre and lying in different planes. {918}The genus _Polyplagia_ alone represents the small subfamily of Polyplagida, distinguished from the other Plagonida by the multiplication of the radial spines, the number of which amounts to seven to nine or more. This increased number is commonly the result of an intercalation of new spines between the three or four primary spines; it is sometimes also effected by stronger development of branches of the latter, which become independent. The following five species of this genus are very different, require further investigation, and perhaps represent different genera:-- 1. _Polyplagia septenaria_, n. sp. Seven radial spines, straight, three-sided prismatic, verticillate, of different sizes; four larger spines correspond to the four axes of a tetrahedron (running from the centre to the four corners), each with five to six verticils of three simple slender branches; one of these four main spines seems to be the apical, the three others the basal spines of _Plagiocarpa_; in the three meridian planes between the latter and the former lie the three smaller spines, diverging upwards, each with two to three verticils. (Similar to _Polyplecta heptacantha_, Pl. 91, fig. 12, but without connection between the branches.) _Dimensions._--Length of the four major spines 0.26, of the three minor 0.11. _Habitat._--Central Pacific, Station 274, surface. 2. _Polyplagia octonaria_, n. sp. Eight radial spines, straight, three-sided prismatic, of equal size, arising in two opposite groups from the two poles of a short common middle rod (as in _Sphærozoum arborescens_, Pl. 4, fig. 8, and in other #Beloidea#). The four spines of each group are divergent, six to eight times as long as the middle rod, each spine armed with three to four verticils of thorny branches. _Dimensions._--Length of the spines 0.15, of the middle rod 0.022. _Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface. 3. _Polyplagia novenaria_, n. sp.