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



Dimensions. Diameter of the sphere 01, pores O005 to 0'015, bars 0'005 to O'OOS ; length 

 of the major spine 015 to 018, of the minor O'Ol to 0'02, basal breadth 0'02. 

 Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



11. Xiphostylus falco, n. sp. (PI. 13, fig. 14). 



Pores irregular, roundish, two to five times as broad as the bars ; sixteen to eighteen on the half 

 equator. Surface smooth. Polar spines cylindrical, very stout, nearly half as thick as the radius 

 of the shell ; major spine two to four times as long as the diameter of the shell ; minor spine 

 obliquely inserted, scarcely longer than the diameter, divided at the end into two short, hook-shaped, 

 curved branches. 



Dimensions. Diameter of the sphere O'OS, pores 0'002 to O'OOS, bars O'OOl ; breadth of the spines 

 0-02, length of the major spine 015 to 0'2, of the minor 0'09. 



Habitat: South Pacific, Station 302, depth 1450 fathoms. 



12. Xiphostylus alca, n. sp. (PI. 14, fig. 13). 



Pores irregular, roundish, two to six times as broad as the bars ; six to eight on the half equator. 

 Each pore with three to six lobes, composed of three to six confluent smaller pores. Surface 

 smooth. Major spine conical, curved, somewhat longer than the axis of the sphere ; minor spine 

 somewhat shorter, pommel-like, edged. 



Dimensions. Diameter of the sphere 0'07, pores O'Ol to 0'02, bars O'OOS ; length of the major 

 spine 0'08, of the minor O'OG, basal thickness 0'02. 



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



13. Xiphostylus edolius, n. sp. (PL 13, fig. 5). 



Pores irregular, roundish, composed of two to six smaller confluent pores. On the half equator 

 six to eight large pores, and twenty to thirty small pores ; bars between the smaller very thin. 

 Surface a little rough. Major polar spine conical, S-shaped, about twice as long as the axis of the 

 shell ; minor spine pommel-shaped, edged, scarcely as long as its radius. 



Dimensions. Diameter of the sphere 012, large pores O'Ol to 0'03, small pores 0'004 to O'OOS, 

 bars O'OOl to 0'004 ; length of the major spine 0'2, of the minor 0'05, basal breadth 0'02. 



Habitat. Central Pacific, Station 273, surface. 



Subgenus 4. Xi%>hostylomma, Haeckel. 



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

 thorny or spiny. 



