REPORT ON THE RADIOLAR1A. 671 



Subgehus 2. Tholostauroma, Haeckel. 

 Definition . Surface of the shell with radial spines or thorns. 



3. Tholostaurus tetrabelonis, n. sp. 



All four cupolas nearly of the same size and form, subregular. Pores regular, circular, 

 hexagonally framed, twice as broad as the bars ; twelve to fourteen in the semicircle of one cupola. 

 Four long and stout conical radial spines, two vertical on the poles of the principal axis, two 

 horizontal on the poles of the transverse axis. 



Dimensions. Major axis of the shell 015, minor 013 ; pores 0'006, bars O'OOS. 



Habitat. South Pacific, Station 288, surface. 



4. Tholostaurus octobelonis, n. sp. 



Two opposite cupolas larger than the two others. Pores subregular, circular, three times as 

 broad as the bars ; ten to twelve in the semicircle of one cupola. Eight long and thin, needle- 

 shaped, radial spines, in pairs crossed in two diagonal planes. 



Dimensions. Major axis of the shell 016, minor 012 ; pores O'Ol, bars O'OOS. 



Habitat. South Pacific, Station 291, surface. 



5. Tholostaurus dodecabelos, n. sp. 



Two opposite cupolas larger than the two others. Pores irregular, roundish, twice to three 

 times as broad as the bars ; six to eight in the semicircle of one cupola. Twelve thin and long 

 radial spines, four on the poles of the two, crossed axes (principal and lateral), eight crossed in two 

 diagonal planes. 



Dimensions. Major axis of the shell 014, minor Oil ; pores O'OOG to O'Ol, bars O'OOS. 



Habitat. North Pacific, Station 244, depth 2900 fathoms. 



6. Tholostaurus polybelonis, n. sp. 



Two opposite cupolas larger than the two others. Pores circular, hexagonally framed, of the 

 same breadth as the bars ; ten to twelve in the semicircle of one cupola. Numerous (twenty to 

 thirty or more) thin, bristle-like, radial spines, about as long as the radius of the shell. 



Dimensions. Major axis of the shell 015, minor axis 012 ; pores and bars 0'007. 



Habitat. Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms. 



Genus 294. Tholoma, 1 n. gen. 



Definition. T holonida with double cortical shell (with external veil), composed 

 of four hemispherical cupolas in cross-form, opposite in pairs on the poles of two axes 

 perpendicular one to another ; central chamber simple (without medullary shell). 



1 Tholoma = Dome-building ; fabafirt. 



