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



Dimensions. — Diameter of the shell O'OS, pores 0-008 to 0-012, bars 0-004; length of the 

 spines 0-2, breadth 0-01. 



Habitat. — North Atlantic, Station 353, surface. 



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



Shell tliick waUed, rough. Pores irregular, roundish, somewhat funnel-shaped double-edged, two 

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

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



I)ime7isions. — Diameter of the shell 0-15, pores 0-007 to D'Ol, bars 0-004; length of the spines 

 0-1, basal breadth 0-025. 



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



21. Hexastylus conifer, n. sp. 



Shell thick walled, rough. Pores iiTegular, 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 0-006 ; length of the spines 

 0-1, basal breadth 0-03. 



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



Subgenus 4. IJexastylvrus, Haeckel. 



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

 spiny, covered wdth 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, jDores Q-Ol to 0-015, bars 0-002 ; length of the spines 

 0-06, basal breadth 0-01. 



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 triangidar pyramidal, as long as the radius, twice as broad as one pore. 



