REPORT ON THE RADIOLARIA. 321 



Subgenus 2. LifJiatractylis, Haeckel. 



.Definition. — Network of the outer shell re,i,ailar, with meshes of equal size aud 

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



6. Lithatractus echiniscus, n. sp. 



Outer shell thorny, thin walled, with rejiular network ; meshes circular, with hexa"onaI fnime, 

 four to five times as broad as the thin bars ; eighteen to twenty on the half equator. From every 

 corner between the three meslies, wdiere three hexagons unite, starts one short, straight, triangular 

 thorn (as in Ellipsoxiphus degans, PI. 14, fig. 7). Proportion of the major axis of the ellipsoid to the 

 minor = 4 : 3. Minor axis twice the diameter of the inner spherical shell, the pores of whicli are 

 half as broad, circular. Polar spines three-sided pyramidal, about as long as the minor axis, as 

 broad at the base as one hexagonal frame. 



Dimensions. — Longer axis of the cortical shell O'OS, shorter axis = 0'06 ; pores 0-004, bars O'OOl ; 

 length of the polar spines O'Oo, basal thickness 0'005 ; diameter of the inner .shell 0'03. 



Habitat. — South Atlantic, off Tristan da Cunha, Station 334, surface. 



7. Lithatjnctus carduelis, n. sp. 



Outer shell thin walled, thorny, with regular network ; meshes circular, simple, four to six times 

 as broad as the thin bars ; ten to twelve on the half equator. Between every three meshes is one 

 short conical spine. Proportion of the major axis to the minor = 6:5. Minor axis equals three 

 times the diameter of the inner spherical shell. Polar spines conical, thick, half as long as the 

 major axis, thicker at the base than one pore. (This species differs from Stylatraetus carduus only 

 by the simple medullary shell.) 



Dimensions. — Longer axis of the ellipsoid Oil! to 016, .shorter axis 01 to 014 ; pores 0-02 to 0-03, 

 bars ODOo ; length of the polar spines O'Oo to 010, basal breadth 0'04; diameter of the medullary 

 sheU 0-03 to O'Ol. 



Habitat. — Central area of the Pacific, Stations 268 to 274, depth 2350 to 2900 fathoms ; also 

 fossil in the rocks of Barbados. 



8. Lithat ractus cirsium, n. sp. 



Outer shell thin walled, thorny, with regular network ; pores circular, simple, small, two to 

 three times as broad as the thin bars ; eighteen to twenty-four on the half equator. Proportion 

 of the major axis to the minor = 4 : 3. Inner .shell ellipsoidal, half as large as the outer. Polar 

 spines cylindrical, blunt, thin, very variable in length (one-fourth to three-fourths of the major 

 axis, not thicker than a mesh). 



Dimensions. — Longer axis of the ellipsoid 0-07 to 009, shorter axis 0-05 to 0-07 ; pores 0-005 to 

 0-006, bars 0-002 ; length of the polar spines 0-02 to 0-06, basal breadth 0-004 ; length of the inner 

 shell 0-04, breadth 0-03. 



Habitat. — North Pacific, Station 244, surface. 



(ZOOL CHALL. EXP. PART XL. — 188.5.) R r 41 



