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



2. Stylosphcera urania, n. sp. 



Radial proportion of the two shells = 4:1. Cortical shell thin walled, smooth ; pores regular, 

 circular, hexagonally framed, twice as broad as the bars ; ten on the half equator. Polar spines 

 conical, as long as the radius of the outer shell. 



Dimensions. Diameter of the cortical shell 0'24, pores 0'012, bars 0-006 ; medullary shell 0'06 ; 

 length of the polar spines 012, basal breadth 0'024. 



Habitat. South Pacific, Station 285, depth 2375 fathoms. 



3. Stylosphcera calliope, n. sp. (PL 16, fig. 6). 



Eadial proportion of the two shells = 3:1. Cortical shell thick walled, smooth ; pores 

 regular, circular, three times as broad as the bars. Each pore on its outer opening with eight 

 regular lobules, flower-like. Nine to ten pores on the half equator. Polar spines three-sided 

 pyramidal, with three strong prominent edges, about as long as the axis, as broad as one pore. 

 (Sometimes, as in the figured specimen, one spine is smaller than the other ; this variety, otherwise 

 identical, may be called SpTicerostylus calliope) 



Dimensions. Diameter of the outer shell 012, pores 0'015, bars O'OOS ; inner shell 0'04 ; 

 length of the polar spine 0'08 to 012, breadth 0'02. 



Habitat. Pacific, central area, Station 268, depth 2900 fathoms. 



4. Stylosphcera clio, n. sp. (PI. 16, fig. 7). 



Eadial proportion of the two shells = 2:1. Cortical shell thick walled, smooth ; pores 

 regular, circular, three times as broad as the bars ; fourteen to sixteen on the half equator. Polar 

 spines three-sided pyramidal, very robust, with thick prismatic edges, about as long as the axis of 

 the cortical shell, one-third as broad at the base. (Sometimes, as in the figured specimen, one 

 spine is greater than the other ; this form may be called Sphcerostylus clio.) 



Dimensions. Diameter of the outer shell 012, pores O'Ol, bars O'OOS ; inner shell, 0'06 ; length 

 of the polar spines 0'08 to 012, basal breadth 0'03 to 0'04. 



Habitat. Pacific, central area ; Station 272, depth 2600 fathoms. 



5. Stylosphcera polyhymnia, n. sp. 



Eadial proportion of the two spheres = 3:1. Cortical shell very thin walled, smooth, with regular, 

 circular pores, three times as broad as the bars ; sixteen to twenty on the half equator. Polar 

 spines cylindrical, pointed, once and a half to twice as long as the axis of the outer sphere, 

 scarcely broader than one pore. The two spheres are connected only by the two opposite beams. 



Dimensions. Diameter of the outer shell 012 to 016, pores 0'006 to 0-009, bars 0'002 to 0'003 ; 

 inner shell 0'04 to 0-05 ; length of the polar spines 018 to 0'22, breadth O'Ol. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, surface. 



