REPORT ON THE RADIOLARIA. 179 



climensive axes = 1:2:4. The radial proportion of the three pairs of spines = 1:3:8. Spines 

 thin cylindrical, at the base angular. 



Dimensions, Diameter of the major shell axis 0'2, middle O'l, minor 0'05 ; length of the 

 major spines 0'3, middle O12, minor 0'04. 



Habitat. Indian Ocean, Madagascar, Rabbe, surface. 



2. Hexastylidium spirale, n. sp. 



Shell thick walled, spherical, thorny, with irregular, roundish pores, three to five tunes 

 as broad as the bars ; six spines very stout, prismatic (as broad as one large pore), with three 

 ring-like, spirally convoluted edges. Two opposite . major spines of extraordinary length, ten to 

 twelve times as long as the shell diameter, the two middle opposite spines being about as long as 

 the latter, the two minor scarcely one-third as long. (Similar to Hexastylus spiralis, PI. 21, fig. 7, 

 but distinguished by the very unequal length of the spines.) 



Dimensions. Diameter of the shell 012 ; length of the major spines 1 to 1'5 mm., middle 

 015, minor 0'04. 



Habitat. Central Pacific, Station 266, surface. 



Subfamily HEXALONCHIDA, 1 Haeckel, 1881, Prodromus, pp. 449, 451. 

 Definition. C ubosphaerida with two concentric spherical lattice-shells. 



Genus 75. Hexalonche, 2 Haeckel, 1881, Prodromus, p. 451. 



Definition. Cub osphserida with two concentric lattice-spheres and six simple 

 spines of equal size. 



The genus Hexalonche is the most simple form, and probably the common ancestral 

 form, of all Hexalonchida, or those Cubosphaerida which possess two concentric 

 latticed spheres, connected by six radial beams. Commonly one shell is intracapsular 

 (medullary shell) and the other extracapsular (cortical shell) ; but sometimes also both 

 shells are extracapsular, and these forms may perhaps be better separated as a peculiar 

 genus Hexadilemma. In Hexalonche all six simple spines are of equal size, and 

 opposite by pairs in three equal dimensive axes, corresponding to the three equal axes 

 of a tessera! crystal. It can be derived from Hexastylus by duplication of the 

 lattice-shell. 



Subgenus 1. Hexalonchara, Haeckel. 



Definition. Pores of the cortical shell regular or subregular, of nearly equal size and 

 similar form ; surface smooth, without radial by-spines (other than the six main spines). 



1 Hexalonchida=Cubospha3rida duplicia = Dyosphferida hexacantha. 



2 Hexalonclie = Shell with six spears ; tl 



