REPORT ON THE RADIOLARIA. 329 



2. Stylatractus fusiformis, n. sp. 



Cortical shell thick walled, smooth, with regular, simple, circular pores, quite as broad as the 

 bars ; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, half as long as 

 the main axis, as broad at the base as the inner medullary shell. (Resembles very nearly Xipha- 

 f.ractus armadillo, PI. 17, fig. 11, but differs in the regular form and equal length of the polar spines.) 



Dimensions. Major axis 017, minor axis 013 ; pores and bars 0'007 ; main axes of both ellip- 

 soidal medullary shells O09 and 0'05 ; length of the polar spines O08, basal breadth 0'04. 



Habitat. Cosmopolitan ; Atlantic, Indian, Pacific, at various depths. 



3. Stylatractus compactus, n. sp. (PI. 17, fig. 4). 



Cortical shell thick walled, smooth, with subregular, circular, double-contoured pores, smaller 

 than the bars ; sixteen to eighteen on the half equator. The thickness of the shell-wall equals the 

 radius of the inner medullary shell. Polar spines short, three-sided pyramidal ; their length and 

 basal thickness variable, but commonly equal to the diameter of the inner medullary shell. 



Dimensions. Major axis 016, minor axis 013 ; pores 0'007, bars O'Ol ; main axes of both 

 ellipsoidal medullary shells 0'09 and 0'04 ; length and basal breadth of the polar spines 0'04 to 

 0-05. 



Hnhitat. Pacific, central area, Stations 270 to 272, depth 2425 to 2925 fathoms. 



Subgenus 2. Stylatractylis, Haeckel. 



Definition. Network of the outer shell regular, with meshes of equal size and 

 similar form ; surface thorny or papillose, covered with small spinules or tubercles. 



4. Stylatractus yiganteus, n. sp. (PI. 17, fig. 1). 



Amphistylus giganteus, Haeckel, 1879, Atlas (pL xvii. fig. 1). 



Cortical shell papillose, very thick walled, with regular network ; pores circular, with double 

 margin, about twice as broad as the bars ; ten to twelve on the half equator. The cortical shell 

 is connected with the outer medullary shell by numerous strong beams, and the inner prolongations 

 of both polar spines are much stronger. The circular pores of the outer medullary shell are three 

 times as large as those of the inner, and equal to those of the cortical shell, but the bars are much 

 thinner. Polar spines very strong, three-sided pyramidal, with spirally contorted edges, as long as 

 the main axis, as broad at the base as the inner medullary shell. 



Dimensions. Major axis of the cortical shell 0'3, minor axis 0'22 ; pores - 02, bars O'Ol ; main 

 axes of the ellipsoidal medullary shells 014 and 0'07 ; length of the polar spines 0'3, basal thick- 

 ness 0'06. 



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



(ZOOL. CHALL. EXP. PAUT XL. 1885.) Rr 42 



