REPORT ON THE RADIOLARIA. 329 



2. Stylatracfus fti.siformis, n. sp. 



Cortical .shell thick walled, snioolli, with regular, simple, circular pores, ijuite as broad as the 

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

 the main axis, as broad at the base as the inner medullary shell. (Eesembles very nearly Xi])ha- 

 fractus armadillo, PI. 17, tig. 11, but differs in the regular form and equal length of the polar spines.) 



Dimensio7is. — Major axis Oi7, minor axis 013 ; pores and bars 0-007 ; main axes of both ellip 

 .soidal medullary .shells 0MI9 and 0'05 ; length of the polar spines 0"08, basal breadth 0'04. 



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



3. Stylatravtas comjxictns, n. ,sp. (PI. 17, fig. 4). 



Cortical shell thick walled, smooth, with sidjregular, 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 ami 

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



Dimensions. — Major axis 016, minor axis O'lo ; 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 O-04 to 

 0-05. 



Habitat. — Pacific, central area. Stations 270 to 272, depth 2425 to 2925 fatlioms. 



Subgenus 2. Stylatractylis, Haeckel. 



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

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



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



Amphistylus gigantrnif, Haeckel, 1879, Atlas (pi. 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 sliell 

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

 of Vioth 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 0"02, bars O'Ol ; main 

 axes of the ellipsoidal medullary shells 0"14 and 0'07 ; length of the polar spines 0'?>, basal thick- 

 ness 0'06. 



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



(ZOOL. CHALL. EXP. PART XL. — 188.5.) Rr 42 



