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



Six main spines triangular pyramidal, with spirally contorted prominent edges, as long as the radius, 

 as broad at the base as one pore. 



Dimensions. — Diameter of the shell 0'13, pores O'Ol, bars 0'002 ; length of the spines 0"06 to 

 0-8, basal breadth O'Ol. 



Habitat. — Central Pacific, Station 266, depth 2750 fathoms. 



12. Hexastylus cochleatus, n. sp. (PI. 21, fig. 1). 



Shell thick walled, covered with numerous short, conical spines (about as large as one pore). 

 Pores regular, circular, three times as broad as the bars ; eight to nine on the radius. Six main 

 spmes triangular pyramidal, with prominent, sph'ally-twisted edges, as long as the diameter of the 

 shell, and twice as broad at the base as one pore. 



Dimensions. — Diameter of the shell 017, pores O^OIS, bars 0'005 ; length of the spines 016, 

 breadth 0-03. 



Habitat. — Mediterranean, Corfu, Haeckel, surface. 



13. Hexastylus setosus, Haeckel. 



Acanthosphwra setusa, Ehrenberg, 1872, Abhaiidl. d. k. Akatl. d. Wiss. Berlin, p. 285, Taf. ix. 

 fig. 11. 



Shell thin walled, covei-ed with numerous short, bristle-shaped spines (not larger than one 

 pore). Pores regTdar, circular, four times as broad as the bars ; thirteen to sixteen on the radius. 

 Six main spines three-sided pjTamidal, scarcely one-third as long as the radius. (In the figure of 

 Ehrenberg, loc. cit., only four spines are in regular, crossed disposition, two others opposite in oblique 

 direction ; this is either an individual abnormality, or an error of drawing ; the same species occurs 

 with six spines exactly regularly disposed in the three dimensive axes.) 



Dimensions. — Diameter of the shell 015 ; pores 0-008, bars 0'002 ; length of the spines 0-02 to 

 0-03, basal breadth 0005. 



Habitat. — Indian Ocean, Zanzibar, PuUen ; Madagascar, Eabbe. 



14. Hexastylus chiloms, n. sp. 



Shell thin walled, covered with numerous bristle-shaped spines (as long as the radius). Pores 

 regular, circular, twice as broad as the bars ; eight to nine on the radius. Six main spines 

 triangular pyramidal, with straight edges, as long as the diameter of the shell, as broad as two pores. 



Dimensions. — Diameter of the shell 0'2, pores 0'02, bars O'Ol ; length of the spines 0"2, basal 

 breadth 005. 



Habitat. — South Atlantic, Station 325, surface. 



15. Hexastylus cleohuli, n. sp. 



Shell thick walled, covered with numerous short, conical spines (twice as lar^e as one pore). 

 Pores regular, circular, of the same breadth as the bars ; twelve to thirteen on the radius. Six 

 main spines conical, as long as the radius, three times as broad as one pore. 



