REPORT ON THE RADIOLARIA. 177 



Dimensions. Diameter of the shell 0'14, pores O'OOo to O'OOS, bars 0'002 ; length of the spines 

 0-06, basal breadth O'Ol. 



Habitat. Central Pacific, Station 271, depth 2425 fathoms. 



24. Hexastylus contortus, n. sp. (PL 21, fig. 12). 



Shell thick walled, covered with bristle-shaped, radial spines, half as long as the radius. Pores 

 irregular, roundish, two to three times as broad as the bars ; seven to eight on the radius. Six 

 spines triangular prismatic, in the distal half spirally twisted like a cork-screw (fig. 12) ; longer 

 than the diameter of the shell, about as broad as one pore. 



Dimensions. Diameter of the shell O12, pores O'OOG to O'OOS, bars 0-003; length of the spines 

 015, breadth 0-015. 



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



25. Hexastylus spiralis, n. sp. (PL 21, fig. 7). 



Shell thick walled, covered with short conical spines. Pores irregular, roundish, two to three 

 times as broad as the bars ; five to six on the radius. Six spines triangular prismatic, with three 

 thin, spirally contorted edges, two to three times as long as the diameter of the shell, about as 

 broad as one large pore. 



Dimensions. Diameter of the shell 0'16, pores O'Ol to 0'02, bars 0'006 ; length of the spines 

 0-3 to 0-5, basal breadth 0'02. 



Habitat. Tropical Western Pacific, Station 225, depth 4475 fathoms. 



Genus 73. Hexastylarium, 1 n. gen. 



Definition. C ubosphserida with one simple lattice-sphere and six simple spines 

 of different sizes ; one opposite pair larger than the other two. 



The genus Hexastylarium differs from its probable ancestral form, Hexastylus, by 

 the unequal growth of the six simple spines ; two opposite spines of one pair being 

 more strongly developed than the four others, which are equal. They correspond 

 therefore to the three axes of a quadratic crystal. 



1. Hexastylarium heteraxonium, n. sp. 



Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the 

 bars ; eight to ten on the radius. Six spines three-sided pyramidal, at the base as broad as one 

 pore. Two opposite major spines longer than the shell diameter ; four others scarcely as long as 

 1 Hexastylarium = Shell with six styles ; derivation from Hemstylus. 



(ZOOL. CHALL. EXP. PART XL. 1885.) K r 23 



