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



Divw7isions. — Major axis (length) of the outer cortical shell 015, minor (breadth) 0'13; pores 

 0'012, bars 0-003; major axis (length) of the inner cortical shell Oil, minor axis (breadth) 009 ; 

 pores 0-006, bars 0-003. 



Habitat. — Indian Ocean, surface, Madagascar, Eabbe. 



4. Staurotholoniuni lenticulare, n. sp. 



Outer cortical shell smooth, lenticular, with cii'cular circumference, with very delicate irregular 

 network and small roundish pores. Its distance from the inner much greater in the four diagonal 

 points than in the four polar points. Inner cortical shell regular, cross-like, with four cupolas of 

 similar size and form. Pores subregular, circular, twice as broad as the bars ; eight to ten in the 

 basal semicircle of one cupola. Medullary shell lenticular. 



Dimensions. — Diameter of the outer cortical shell 0-16, of the inner 0-12 ; pores of the 

 inner O'OOS, bars 0-004. 



Habitat. — North Atlantic, Station 353, surface. 



Subgenus 2. Staurotholoma, Haeckel. 

 Definition. — Surface of the outer cortical shell with radial spines or thorns. 



5. Staurotholonium octodoratium, n. sp. 



Outer cortical shell of the same form and structure as the inner, but twice as large, both 

 principal domes somewhat larger than both lateral. Pores subregular, circular, of the same breadth 

 as the bars ; five to six in the semicircle of one inner, eight to ten of one outer cupola. Eight thin 

 and long bristle-like spines, opposite in pairs in two crossed diagonal planes. 



Dimensions. — Major axis of the outer cortical shell 0-15, minor 0-12 ; major axis of the inner 

 cortical shell 007, minor 0-06 ; i>ores and bars 0*005. 



Habitat. — North Pacific, Station 231, surface. 



6. Staurotholonium octodoronium, n. sp. (PI. 10, fig. 11). 



Outer cortical shell of the same form as the inner, both little distant ; network of the outer 

 irregular and delicate. Pores of the inner regular, circular, twice as broad as the bars ; seven to nine 

 in the basal semicircle of one cupola. Both lateral domes larger than the principal. Eight long 

 and thin, cylindrical radial spines opposite in pairs in two crossed diagonal planes. 



Dimensions.— l.iB.iov axis of the outer cortical shell 0-2, minor 0"18 ; major axis of the inner 

 cortical shell 0-16, minor 0-14; pores 0-008, bars 0-004. 



Habitat. — South Pacific, Station 288, surface. 



