REPORT ON THE RADIOLARIA. 205 



pyramidal, longer than the diameter of the octahedron, arising from its sLx corners, as broad at the 

 base as one mesh. 



Dimensions. — Diameter of the shell OlS, meshes 0-01 to 0'012, bars ()-001 ; length of the spines 

 0-2, basal breadth O'Ol. 



Habitat. — South Pacific, Station 300, surface. 



Genus 86. Hexadoras} Haeckel, 1881, Prodromus, p. 455. 



Definition. — C u b o s p h je r i d a with spongy spherical shell and one simple 

 latticed medullaiy shell in its centre, having six simple spines of equal size. 



The genus Hexadoras exhibits the same structure of the spongy shell as Sponyo- 

 plegma, but differs from it in the jiroduction of six dimensive spines. In the centre 

 lies one simple, latticed, medullary shell, which is either spherical or octahedral. 

 In the latter case the six spines arise froin the six corners of the octahedron. 



1. Hexadoras axophcena, n. sj). 



Medullary shell spherical, with regular hexagonal meshes, twice as broad as the bars. Cortical 

 shell entirely enclosing it, with loose irregular framework and thorny surface. Diameter of the 

 outer shell three times as large as that of the inner. Six radial spines arising from the medidlary 

 shell, four to five times as long as the radius of the cortical shell, three-sided prismatic, with 

 straight dentated edges. 



Dimensions. — Diameter of the outer shell 0"15, inner 0'05 ; length of the spines 0'3 to 0'4. 



Habitat. — Central Pacific, Station 265, depth 2900 fathoms. 



2. Hexadoras lychnosphcera, n. sp. 



Medullary shell spherical, with regular, chcular, hexagonally framed pores, three times as broad 

 as the bars. Cortical shell enveloping it, with loose irregular framework and spiny surface. 

 Diameter of the outer shell eight times as large as that of the inner. Six radial spines arising from 

 the inner shell, three-sided prismatic, with dentated, spirally contorted edges, seven times as long 

 as the diameter of the medullary shell, with three lateral branches at the distal end (similar to 

 Lychnosphmra, PI. 11, fig. 1). 



Dimensions. — Diameter of the outer shell 0'5, inner 0'06 ; total length of the sjiines 0'4, 

 breadth Q-Ol. 



Habitat. — Central Pacific, Station 270, depth 2925 fathoms. 



3. Hexadoras octahedrum, n. sp. 



Medullary shell regular octahedral, with irregular polygonal meshes, five times as broad as the 

 bars. Cortical shell enveloping it, with dense spongy framework, also octahedral with rough surface. 



' Hexadoras ='!i'he\\ with six spears ; fjaoojar. 



