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 sLxty, three-sided prismatic radial spines, bearing eight to ten verticils 

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

 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 meduUary shell. The 

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

 A rachnosphcera. ) 



Dimensions. — Diameter of the spongy cortical shell O'fi, of the medullary shell 0"1. 



Habitat. — Tropical Pacific, Station 200, surface. 



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



Definition. — A strospliserifla witli a single, sjDlierical, 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 l)y the radial spines connecting both shells. 



Subgenus 1. Rhizoplegmarium, Haeckel. 

 Definition. — No free lateral l)ranches of the radial spines between the two shells. 



1. Rhizoplegma polyacanthvm, 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 meduUary 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 meduUary sheU, which exhibits regular, hexagonal meshes. 



^ Rhizoplegma = 'Root-shR:ped wicker-vork ; pil^a, v'xi'/f/.oe. 



