176 THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. Diameter of the shell 0'08, pores O'OOS to 0'012, bars 0'004; length of the 

 spines - 2, breadth O'Ol. 



Habitat. North Atlantic, Station 353, surface. 



20. Hexastylus marginatus, n. sp. (PI. 21, fig. 10). 



Shell thick walled, rough. Pores irregular, roundish, somewhat funnel-shaped double-edged, two 

 to three times as broad as the bars ; twelve to fourteen on the radius. Six spines three-sided 

 pyramidal, somewhat longer than the radius, three times as broad as one pore. 



Dimensions. Diameter of the shell 015, pores 0'007 to O'Ol, bars O004; length of the spines 

 01, basal breadth 0'025. 



Habitat. South Pacific, Station 295, depth 1500 fathoms. 



21. Hexastylus conifer, n. sp. 



Shell thick walled, rough. Pores irregular, roundish, scarcely broader than the bars ; fifteen 

 to sixteen on the radius. Six spines conical, as long as the radius, five to seven times as broad as 

 one pore. 



Dimensions. Diameter of the shell 0'18, pores and bars 0'004 to - 006 ; length of the spines 

 01, basal breadth 0'03. 



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



Subgenus 4. Hexastylurus, Haeckel. 



Definition. Pores irregular, of unequal size or form ; surface of the spherical shell 

 spiny, covered with numerous conical or bristle-shaped by-spines. 



22. Hexastylus dictyotus, n. sp. (PI. 21, figs. 8, 9). 



Shell thin walled, spiny ; short spines conical, smaller than the pore-breadth. Pores irregular, 

 polygonal, five to seven times as broad as the bars ; four to six on the radius. Six spines triangular 

 pyramidal, longer than the radius, about as broad as one smaller pore. 



Dimensions. Diameter of the shell 0'09, pores O'Ol to 0'015, bars 0'002 ; length of the spines 

 0-06, basal breadth O'Ol. 



Habitat. Central Pacific, Station 272, depth 2600 fathoms. 



23. Hexastylus hirsutus, n. sp. 



Shell thin walled, densely covered with bristle-shaped, radial spines, half as long as the six 

 main spines. Pores irregular, polygonal, three to four times as broad as the bars ; eight to ten on 

 the radius. Six spines triangular pyramidal, as long as the radius, twice as broad as one pore. 



