REPOET ON THE RADIOLARIA. 677 



Subfamily 3. CUBOTHOLIDA, Haeckel. 



Definition. T holonida with triaxial growth ; cupolas lying in pairs on the six 

 sides of a cubical central chamber, opposite at the poles of three axes perpendicular one 

 to another. (Shell commonly seven-chambered, with six domes surrounding the central 

 chamber.) 



Genus 297. Tholocubus, 1 n. gen. 



Definition. T holonida with simple cortical shell (without external veil), 

 composed of six hemispherical cupolas, opposite in pairs on the poles of three axes 

 perpendicular one to another, covering six sides of the simple cuboidal central chamber 

 (without medullary shell). 



The genus Tholocubus is the most simple form of the Cubotholida, or of the 

 Tholonida with domes situated in three axes perpendicular one to another ; six 

 hemispherical cupolas lying on the six sides of a cuboidal central chamber ; this latter 

 contains no medullary shell. Tholocubus may be derived phylogenetically either from 

 Tholostaurus by apposition of two opposite domes on the flat sides of the cross-shell, 

 or from Cubotholus by loss of the medullary shell. 



Subgenua 1. Tholocubulus, HaeckeJ. 

 Definition. Surface of the shell smooth or rough, without radial spines. 



1. Tholocubus tessellatus, n. sp. (PI. 10, fig. 12). 



Surface of the shell smooth, without radial spines. Pores regular, circular, hexagonally framed, 

 twice as broad as the bars ; eight to twelve pores on the semicircle of one cupola. Principal cupolas 

 smaller than the lateral, larger than the sagittal cupolas. 



Dimensions. Diameter of the shell 015 ; pores O'Ol, bars 0'005. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



2. Tholocubus tesserarius, n. sp. 



Surface of the shell rough, without radial spines. Pores irregular, roundish, once to three 

 times as broad as the bars ; twelve to sixteen pores in the semicircle of one cupola. All six 

 cupolas nearly of the same size. 



Dimensions. Diameter of the shell 016 ; pores 0'04 to O'OOS, bars 0'003. 



Habitat. North Atlantic, Station 353, depth 2965 fathoms. 



1 Tholocubus = Cube with six cupolas on its sides ; rfo'Xof, xi//3f. 



