EEPORT ON THE RADIOLARIA. 363 



(which genus contains also a number of other Prunoidea), partly by me (1862) as 

 Didymocyrtis. Both names are inadequate, as allusions to quite different families of 

 Nassellaria, but may be retained as significations of subgeneric divisions. Cyphonium differs 

 from Cypkanta by the double medullary shell, which is either spherical or lenticular. 



Subgenus 1. Ommatospyris, Ehrenberg (partim). 

 Definition. Surface of the cortical shell smooth, without thorns or spines. 



1. Ci/phonium coscinoides, n. sp. 



Ommatogpyris coscinoides, Haeckel, 1881, Prodromus, p. 462. 



Cortical shell thin walled, with smooth surface ; pores regular, hexagonal, three to four times 

 as broad as the bars ; five to six on the half meridian, eight to nine on the half equator of each 

 chamber. Medullary shells both spherical. (The cortical shell of this species is nearly the same as 

 that of Cyplianta colpodes, and as the middle part of the cortical shell of Panartus diploconus, 

 Pi. 40, fig. l.) 



Dimensions. Main axis of the cortical shell Oil, equatorial axis 0'06; greatest breadth of the 

 chambers 0'08 ; pores 0'013, bars 0'003. 



Habitat. North Pacific, Station 244, surface. 



2. Cyphonium virgineum, n. sp. (PI. 39, figs. 12, 12a). 



Ommatospyris oirginea, Haeckel, 1881, Prodromus et Atlas (pi. xxxix. fig. 12a). 



Cortical shell thick walled, with smooth surface (sometimes a little rough with very small 

 thorns) ; pores subregular, circular, with hexagonal elevated frames, about as broad as the bars ; ten 

 to twelve on the half meridian, sixteen to eighteen on the half equator of each chamber. Medullary 

 shells (fig. 12a) both spherical. (Sometimes, as in the figured specimen, the shell is somewhat 

 irregular, 'an individual abnormality.) 



Dimensions. Main axis of the cortical shell 013 to 015 ; equatorial axis of the structure 

 0-08 to 0-09, of each chamber 01 to 012, pores and bars O'OOS to 0007. 



Habitat. Pacific, western tropical part, Station 225, depth 4475 fathoms. 



3. Cyphonium ethmarium, n. sp. 



Ommatospyris ethmaria, Haeckel, 1881, Prodromus, p. 462. 



Cortical shell thin walled, with quite smooth surface ; pores subregular, circular (without 

 hexagonal frame), twice as broad as the bars ; nine to ten on the half meridian of each chamber, 

 sixteen to eighteen on its half equator. Medullary shells both spherical. (This species resembles 

 the proximal internal chambers of Peripanartus atractus, PI. 40, fig. 7.) 



Dimensions. Main axis 013, equatorial axis 0'07 ; greatest breadth 0'09 ; pores 0'006, 

 bars 0-003. 



Habitat. Equatorial Atlantic, Station 347, surface. 



