REPORT ON THE RADIOLARIA. 415 



Dimensions. Diameter of the disk 0'06, of the pores 0'007 ; length of the spine 0'12, basal 

 breadth 0'02. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



Subgenus 2. Theodisciira, Haeckel. 



Definition. Angles between the three radial spines unequal, two paired angles 

 equal, larger or smaller than the odd angle (triangle isosceles). 



4. Tneodiscus vanitatis, n. sp. 



Disk nearly spherical, with smooth surface. Pores irregular, roundish ; eight to ten on the 

 radius. Three angles between the spines unequal ; one odd angle larger than both others. Spines 

 pyramidal, of unequal size ; one odd spine larger, both others smaller than the shell diameter. 



Dimensions. Diameter of the disk - 12, pores 0'004 to O'OOG ; length of the odd spine 0'2, of 

 the paired spines O'l. 



Habitat. South Atlantic, Station 335, depth 1425 fathoms. 



5. Theodiscus nirvana, n. sp. 



Disk a flat biconvex lens, about twice as broad as thick. Pores regular, circular ; ten to twelve 

 on the radius. Three angles between the spines unequal ; one odd angle smaller than both others. 

 Spines prismatic, very long and thin, twice as broad as one pore, ten to twelve times as long as 

 the shell diameter. 



Dimensions. Diameter of the disk 01, pores O'OOo ; length of the spines 1 to 1'2 or more, 

 breadth O'Ol. 



Habitat. Indian Ocean, Ceylon, surface, Haeckel. 



Genus 179. Crucidiscus^ n. gen. 



Definition. Cenodiscida with four radial spines on the margin of the disk, 

 crossed in the equatorial plane. 



The genus Crucidiscus is the most simple form of the Staurodiscida, or of 

 the numerous D i s c o i d e a (belonging to different families) in which the margin of 

 the disk bears four radial spines, lying in the equatorial plane, and crossed at right 

 angles. Whilst commonly the internal shell-cavity of Crucidiscus is quite simple, in 

 one case it bears four centripetal axial rods, as inner prolongations of the outer radial 

 cross-spines, perhaps indications of a lost medullary shell (comp. p. 410). 



1 Crucidiscus = Disk with cross. 



