EEPOET ON THE RADIOLARIA. 197 



medullary shells with smaller, irregular roundish pores. Six spines three-sided pyramidal, longer 

 than the radius of the outer shell, one to two times as broad as one larger pore. 



Dimensions. Diameter of the outer shell 0'12, middle 0'045, inner 0'015 ; cortical pores O'OOG 

 to 0-018, bars 0'002 ; length of the spines 0'06 to 0'12, basal breadth 0'02 to 0'03. 



Habitat. Central Pacific, Stations 266 to 272, at various depths. 



17. Hexacontium polygonale, n. sp. 



Cortical shell thick walled, smooth. Pores irregular roundish, with polygonal frames, two to 

 four times as broad as the bars ; eight to twelve on the radius. Kadial proportion of the three 

 spheres = 1 : 3 : 10. Six spines pyramidal, nearly as long as the diameter of the outer shell, with 

 six to nine prominent edges (along the corner number of the polygonal meshes). 



Dimensions. Diameter of the outer shell 0'2, middle 0'06, inner 0'02 ; cortical pores O'OOS to 

 0-016, bars 0'004; length of the spines 016 to 0'18, basal breadth 0'02. 



Habitat. South Pacific, Station 295, depth 1500 fathoms. 



18. Hexacontium antarcticum, n. sp. 



Cortical shell thin walled, smooth, with irregular roundish pores, eight to ten on the radius, two 

 to four times as broad as the bars. Eadial proportion of the three spheres = 1:3:9. Both 

 medullary shells with smaller roundish irregular pores. Six spines conical, pyramidal at their origin, 

 about as long as the radius, as broad as one larger mesh. 



Dimensions. Diameter of the outer shell 0'18, middle 0'06, inner 0'02 ; cortical pores 0'006 

 to 0-012, bars 0'003 ; length of the spines O'l, basal breadth 0'12. 



Habitat. Antarctic Ocean, Station 157, depth 1950 fathoms. 



Subgenus 4. Hexacontura, Haeckel. 



Definition. Pores of the cortical shell irregular, of different size or form ; surface 

 covered with numerous conical papillae or bristle-shaped, radial by-spines (other than the 

 six main spines). 



19. Hexacontium papillosum, n. sp. (PI. 24, fig. 5). 



Cortical shell thick walled, papillose. Pores irregular roundish, often somewhat lobed, five to 

 six on the radius, two to four times as broad as the bars. Eadial proportion of the three spheres = 

 1:2-5: 5. Both medullary shells with subregular circular pores (inner much smaller). Six radial 

 spines short and stout, pommel or club shaped, with three prominent wings, about as long as the 

 shell radius, and as broad as the medullary shell. 



f Dimensions. Diameter of the outer shell O'l, middle 0'05, inner 0'02 ; cortical pores 0'006 to 

 0-012, bars O'OOS; length of the spines 0'05, bars 0'02. 



Habitat. Central Pacific, Stations 266 to 272, at various depths. 



