REPORT ON THE RADIOLARIA. 371 



Genus 160. Cyphinidium, 1 n. gen. 



Definition. C yphinida with simple cortical shell and double medullary shell, 

 with two opposite polar spines (or bunches of polar spines) on the poles of the main 

 axis. 



The genus Cyphinidium differs from Cyphinus only in the duplication of the 

 medullary shell, which is composed of two concentric spheres or somewhat compressed 

 lenticular spheroids. It exhibits therefore the same relation to Cyphinus that Styla- 

 tractus in the Druppulida bears to Lithatractus. Possibly the two former genera are 

 derived from the two latter by an annular constriction in the equatorial plane. 



Subgenus 1. Cyphinidoma, Haeckel. 



Definition. On both poles of the cortical shell one single polar spine or a bunch of 

 polar spines. 



1. Cyphinidium amphistylium, n. sp. 



Cortical shell thick walled, with smooth surface, and subregular, circular pores, twice to three 

 times as broad as the bars ; eight to ten on the half meridian, sixteen to eighteen on the half 

 equator of each chamber. Both medullary shells spherical. The cortical shell resembles very 

 much that of Cannartiscus ampkiconiscus (PI. 39 } fig. 19), but exhibits instead of the hollow polar 

 tubes two strong solid polar spines of conical form, half as long as the main axis, and as broad at 

 the base as the inner medullary shell. 



Dimensions. Main axis of the cortical shell (without polar spines) 0'14, greatest breadth O'l ; 

 pores O'OOS, bars 0004 ; length of the polar spines 0'08, basal thickness 0'02. 



Habitat. North Pacific, off Japan, Station 241, depth 2300 fathoms. 



2. Cyphinidium apicatum, Haeckel. 



Ommatospyris apicata, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 

 p. 317. 



Cortical shell thin walled, with thorny surface, and irregular, polygonal pores, three to five times 

 as broad as the thin bars ; eight to nine on the half meridian, thirteen to fifteen on the half equator 

 of each chamber. On both poles a bunch of four to eight strong conical spines, the central of 

 which (in the main axis) is much larger than the others, and twice as long as the diameter of the 

 outer spheroidal medullary shell ; size and number of the polar spines is very variable (commonly 

 five to six). 



1 Cyphinidium = Small Cyphinus; nvQivfouiii. 



