REPORT ON THE RADIOLARIA. 665 



Subgenus 2. Tholartissa, Haeckel. 

 Definition. Surface of the shell with radial spines. 



4. Tholartus tripanis, n. sp. 



Central chamber of the same size as both cupolas. Surface of the shell thorny, everywhere 

 covered with short conical radial spines, about as long as the cupolas. Pores regular or subregular, 

 circular, twice as broad as the bars; eight to ten on the half meridian. 



Dimensions. Length of the shell 01, breadth 012 ; pores O'Ol, bars 0'005. 



Habitat. South Pacific, Station 295, surface. 



5. Tholartiis sagitta, n. sp. 



Central chamber twice as large as both cupolas. Surface of the shell spiny, with eight to 

 twelve regularly (?) distributed radial spines, radiating from the two constrictions between the three 

 chambers. Spines needle-shaped, very thin and long. Pores subregular or irregular, roundish or 

 circular, about three times as broad as the bars ; twelve to sixteen on the half meridian. 



Dimensions. Length of the shell Oil, breadth 015 ; pores O'Ol, bars 0'003. 



Habitat. North Pacific, Station 244, surface. 



Genus 290. Tholodes, 1 n. gen. 



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

 two hemispherical cupolas, opposite on the poles of one axis ; central chamber between 

 them simple (without medullary shell). 



The genus TJiolodcs (PL 10, fig. 2) differs from Thalartus, its probable ancestral 

 form, only in the duplication of the shell ; the outer shell has exactly the same 

 three-jointed form as the inner ; both are connected by eight radial beams, lying in 

 two diagonal planes and corresponding to the eight frontal spines of Tetrapyle 

 octacantha. Possibly Tholodes may also be descended from Amphitholonium by loss 

 of the medullary shell. I have observed only one single specimen of this genus. 



1. Tholodes cupula, n. sp. (PI. 10, fig. 2). 



Outer shell of the same form and structure as the inner shell. Central chamber larger than 

 both cupolas. Surface a little rough, without radial spines. Distance of both shells equals the 

 height of the outer cupolas. Pores of both shells regular, circular, three times as broad as the 



1 Tholodes = Cupola-shaped ; doAaidwf rel fohofilri;. 

 (ZOOL. CHALL. EXP. PART XL. 1885.) Er 84 



