REPORT ON THE RADIOLARIA.. 387 



Both distal chambers nearly hemispherical (with a circle of ten to twelve very large square pores 

 at their base, the other pores very small). From both poles arises a single, strong, conical spine, 

 half as long as the main axis. The internal cortical shell is very much like that of Panarium 

 tuhidarium (PI. 40, tig. 9), but differs by the solid polar spines (instead of the hollow tubules) and 

 by the formation of an external, cylindrical, very thin, cortical shell, which envelops the whole 

 internal, and is connected with it by numerous beams. The surface of the external shell is quite 

 smooth, 9,nd perforated by innumerable very small roundish pores. 



Bimensions. — Main axis of the external cortical shell 0'25, of the internal 019; transverse 

 axis of the former 013, of the latter O'OS ; pores of the proximal chambers of the internal shell 

 0-01, bars 0-003; pores of external cortical shell 0'002, bars O'OOl; length of both polar spines 

 012, basal thickness of them 0'02. 



Habitat. — South Atlantic, near Tristan da Cunha, Station 333, depth 2025 fathoms. 



Subgenus 2. Peripanicula, Haeckel. 



Definition. — On both poles of the main axis a bunch or a cu-cle of aggregated 

 polar spines. 



2. Peripanicium amphicorona, n. sp. (PI. 40, fig. 8). 



Peri;fianartus amphicorona, Haeckel, 1881, Prodromus et Atlas (pi. xl. fig. 8). 



Internal cortical shell with four very unequal chambers. Both proximal chambers kidney- 

 shaped, with subregular, polygonal pores, three times as broad as the bars. Both distal chambers 

 double cone-shaped ; the proximal cone of these formed by a circle of ten to twelve radial beams, 

 which separate the same number of large square meshes ; the distal cone with five to six circles of 

 very small roundish, irregular pores. The continuation of the thin porous lamella of this distal 

 cone forms the external cortical shell, whose surface is a little rough with innumerable very small 

 thorns. On both poles is a large circular opening (nearly as broad as the equatorial constriction 

 of the inner shell), surrounded by a delicate crown of thorns. The spines of this crown equal the 

 diameter of the polar opening ; they are very thin and bristle-like, connected by a few bridges and 

 diverge outwards. 



Dimensions. — Main axis (without the crowns of polar thorns) 0'26, greatest breadth (in the 

 equator of the proximal chambers) 015 ; equatorial constriction of the external .shell 012, of the 

 internal 0'07 ; pores of the proximal chambers of the internal cortical shell O^Ol, of the external 

 0'005, bars O'OOS ; diameter of the circular polar opening 0'05 ; length of the polar spines 0'05. 



Habitat. — Pacific, central area, Station 271, depth 2425 fathoms. 



3. Peripanicium coronai-ium, n. sp. 



Internal cortical shell with four unequal chambers. Both proximal chambers kidney-shaped, 

 with irregular, roundish pores, twice to four times as broad as the bars. Both distal chambers cap- 

 like, with a basal circle of ten to twelve lai-ge square meshes, the other pores very small. External 



