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



4. Staurotholus octostylus, n. sp. 



The two lateral cupolas larger than the two principal cupolas. Pores subregular, circular, twice 

 as broad as the bars ; ten to twelve in the semicircle of one cupola. Medullary shell hexagonal, 

 connected with each ring-like constriction by eight strong cylindrical radial spines (longer than 

 the whole shell), lying in two crossed meridian planes, and corresponding to the eight diagonal 

 wing-spines of Tetrapyle octacantha. 



Dimensions. Major axis of the cortical shell 012, minor 01 ; pores - 008, bars 0'004. 



Habitat. Pacific, central area, Station 274, depth 2750 fathoms. 



5. Staurotholus decastylus, n. sp. 



The two principal cupolas twice as broad and high as the two lateral cupolas. Pores subregular, 

 circular, four times as broad as the bars ; six to eight in the semicircle of one cupola. Ten 

 long and thin radial spines with thickened conical bases, about as long as the major axis of the 

 shell, by inner prolongations connected with the lentelliptical medullary shell ; two polar spines in 

 the principal axis, eight wing-spines in two crossed diagonal planes. 



Dimensions. Major axis 012, minor 01 ; pores 0'012, bars 0'003. 



Western Tropical Pacific ; Station 224, depth 1850 fathoms. 



6. Staurotholus dodecastylus, n. sp. (PL 10, fig. 9). 



The two lateral cupolas larger than the two principal cupolas. Pores subregular, circular, three 

 times as broad as the bars ; five to seven in the semicircle of one cupola. Twelve strong cylin- 

 drical radial spines, four on the poles of the two larger axes (two principal and two lateral), eight 

 wing-spines in two crossed diagonal planes. Medullary shell hexagonal. 



Dimensions. Major (lateral) axis Oil, minor (principal) 0'09 ; pores 0'009, bars 0'003. 



Habitat. Tropical Atlantic, Station 348, surface. 



7. Staurotholus poly stylus, n. sp. 



The two principal cupolas larger than the two lateral cupolas. Pores irregular, roundish, twice 

 to three times as broad as the bars ; ten to twelve in the semicircle of one cupola. On the surface 

 numerous thin bristle-shaped spines (twenty to thirty or more). 



Dimensions. Major axis 014, minor Oil; pores 0'006 to O'Ol, bars 0'003. 



Habitat. North Pacific, Station 231, surface. 



Genus 296. Staurotholonium, 1 n. gen. 



Definition. Tholonida with double cortical shell (with external veil), com- 

 posed of four hemispherical cupolas in cross-form, opposite in pairs on the poles 

 of two axes perpendicular one to another ; central chamber Zarao^7/a-shaped (with 

 medullary shell). 



1 Staurotholonium = Small shell with cupolas cross-wise disposed; meevpo;, 



