REPORT ON THE RADIOLARIA. 193 



= 1:3:6. Both medullary shells of the same structure, but with smaller pores. Six spines 

 triangular pyramidal, nearly as long as the diameter of the outer shell, three times as broad at the 

 base as one pore. 



Dimensions. Diameter of the outer sphere O'l, middle 0'05, inner O016 ; cortical pores 

 and bars O'OOS ; length of the spines 0'08, basal breadth 0'025. 



Habitat. Fossil in Tertiary rocks of Sicily, Grotte, Stohr. 



4. Hexacontium Icevigatum, n. sp. (PL 24, fig. 6). 



Cortical shell thick walled, quite smooth. Pores regular circular, with double margins, eight to ten 

 on the radius, of the same breadth as the smooth bars. Eadial proportion of the three spheres 

 = 1:2:6. All three spheres connected by six very thin radial beams, which are prolonged 

 outside into six short, stout, triangular, pyramidal spines, half as long as the radius of the 

 outer shell. 



Dimensions. Diameter of the outer shell 013, middle - 04, inner 0'02 ; cortical pores and bars 

 0-008 ; length of the spines 0'04, basal breadth 0'02. 



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



5. Hexacontium triplosphcerium, n. sp. 



Cortical shell thick walled, smooth. Pores regular circular, three times as broad as the 

 bars; ten to twelve on the radius. Eadial proportion of the three spheres = 1 : 3 : 10. Six 

 spines conical, about as long as the radius of the cortical shell. 



Dimensions. Diameter of the outer shell 0'16, middle 0'05, inner 0'016 ; cortical pores 0'012, 

 bars 0-004 ; length of the spines 0'07, basal breadth 0'02. 



Habitat. Central Pacific, Station 268, depth 2900 fathoms. 



6. Hexacontium octahedrum, n. sp. 



Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between 

 the spine-bases) and with smooth surface ; its pores regular circular, five to seven on the radius, 

 four times as broad as the bars. Eadial proportion of the three shells =1:3:9. Both medullary 

 shells spherical, with very small circular pores. Six inner bars very thin ; six outer spines (their 

 prolongations) triangular pyramidal, as long as the radius of the outer shell. (Differs from 

 Hexalonclie octahedra, PI. 22, fig. 8, almost solely in the duplication of the medullary shell.) 



Dimensions. Diameter of the outer shell 0'12, middle 0'04, inner 0'013. 



Habitat. Central Pacific, Station 271, depth 2425 fathoms. 



7. Hexacontium circumtextum, n. sp. (PI. 25, figs. 7, 7a). 



Cortical shell double, enclosing a simple medullary shell. Eadial proportion of the three 

 spheres = 3 : 10 : 12. Inner cortical shell very thick walled, with regular circular, double-edged 

 pores, four times as broad as the bars ; seven to nine on the radius. From each nodal-point between 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 25 



