REPORT ON THE RADIOLARIA. 275 



2. Spongopila verticillata, n. sp. 



Medullary shell with regular, hexagonal meshes, four times as broad as the bars. From 

 its surface arise forty to sixty, three-sided prismatic radial spines, bearing eight to ten verticils 

 of lateral branches, each verticil with six forked branches (two from each edge). By irregular 

 ramification of these branches, and communication in all directions, the loose spongy framework 

 of the cortical shell originates, which is six times as broad as the medullary shell. The 

 free distal ends of the spines are as long as the shell radius. (May be derived from 

 Arachnosphccra) 



Dimensions. Diameter of the spongy cortical shell 0'6, of the medullary shell O'l. 

 . Habitat. Tropical Pacific, Station 200, surface. 



Genus 116. Rhizoplegma, 1 Haeckel, 1881, Prodromus, p. 456. 



Definition. A strosphserida with a single, spherical, latticed medullary shell, 

 which is not armed with by-spines, but connected by stout radial main spines with 

 the spongy cortical shell. 



The genus Rhizoplegma is immediately allied to the foregoing Spongopila, but differs 

 from it in the large interval separating both shells. In this interval lies the wall of 

 the central capsule, which is only pierced by the radial spines connecting both shells. 



Subgenus 1. Rhizoplegmarium, Haeckel. 

 Definition. No free lateral branches of the radial spines between the two shells. 



1 . Rhizoplegma polyacanthum, n. sp. 



Spongy cortical shell with a very fine dense framework and nearly smooth surface (without 

 superficial by-spines). Its inner cavity is four times as broad as the medullary shell, which 

 exhibits regular, hexagonal meshes. Eadial spines sixty to eighty, three-sided prismatic, with 

 three smooth edges, without lateral branches between both shells ; their free outer part as long as 

 the shell radius. 



Dimensions. Diameter of the spongy cortical shell 0'3, of its inner cavity 0'2, of the medullary 

 shell 0-05. 



Habitat. Central Pacific, Station 274, surface. 



2. Rhizoplegma spirale, n. sp. 



Spongy cortical shell with a very delicate loose framework and bristly surface. Its inner 

 cavity three times as broad as the medullary shell, which exhibits regular, hexagonal meshes. 



1 Rhizopleyma = Root-shaped wicker-work ; <;<, a^.i-yft.a. 



