REPORT ON THE RADIOLARIA. 185 



triangular spines is surrounded at the base by three small roundish pores (between the three 

 wings of its base), and further by a coronal of six very large pores, three of which are 

 pentagonal, and the other three (alternating) heptagonal. The six basal coronals are separated 

 by irregular smaller pores. Medullary shell thin walled, with regular hexagonal pores (three on 

 the radius) and thin bars, connected with the outer shell by six thin triangular prismatic radial 

 beams, which are prolonged outside into short pyramidal spines (half as long as the radius). 



Dimensions. Diameter of the outer shell O2, thirty-six larger pores of the coronals 0'03 to 

 - 04, smaller pores between them O'Ol to 0'02, bars 0'005 ; inner shell 0'05 (with pores of 

 0-008) ; length of the spines 0'05, basal breadth 0'03. 



Habitat. South Atlantic, off Buenos Ayres, Station 323, depth 1900 fathoms. 



19. Hexalonche pythagorcea, n. sp. (PI. 22, fig. 1). 



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

 irregular roundish, twice to eight times as broad as the bars, of very different size ; usually 

 in the space between every three spines are three or six larger pores, separated by numerous 

 smaller pores (often the disposition of the larger pores is much more regular than in the 

 figured specimen). Medullary shell with regular circular pores, connected with the outer by six 

 very thin radial beams, which are prolonged outside into six short triangular pyramidal spines 

 about as long and broad as the half radius. 



Dimensions. Diameter of the outer shell 012, pores O'OOS to 0'03, bars 0'004 ; inner shell 

 0-04 ; length of the spines 0'04, basal breadth 0'03. 



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



20. Hexalonche aristarchi, 11. sp. (PI. 22, fig. 3). 



Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores 

 irregular polygonal, of very variable size and form, twice to six times as broad as the bars ; 

 six to ten on the radius. Medullary shell with regular hexagonal pores, connected with the 

 outer by six very thin radial beams, which are prolonged outside into six triangular pyramidal 

 spines, nearly as long as the radius. 



Dimensions. Diameter of the outer shell O'l, pores O'OOS to 0'02, bars O'OOS ; inner shell 

 0-025 ; length of the spines 0'05, basal breadth O'Ol. 



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



21. Hexalonche ekphantcea, n. sp. 



Cortical shell thin walled, smooth, four tunes as broad as the medullary shell Pores irregular 

 roundish, of very variable size and form, twice to six times as broad as the bars, ten to fifteen on the 

 radius. Six spines cylindro-conical, longer than the diameter of the shell. 



Dimensions. Diameter of the outer shell 0'2, pores 0'004 to 0'012, bars 0'002 ; inner shell 0'05; 

 length of the spine 0'3, basal breadth O'Ol. 



Habitat. Indian Ocean, Sunda Strait, surface, Eabbe. 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 24 



