REPORT ON THE RADIOLARIA. 383 



only by the external cortical shell enveloping the whole internal one, in the same manner as in 

 Peripanartus cylindrus (PL 40, fig. 6). The two shells are connected by numerous radial rods. The 

 surface of the outer cortical shell is quite smooth, its irregular, roundish pores about half as large as 

 those of the inner cortical shell. 



Dimensions. Main axis of the external cortical shell 0'27, of the internal - 2 ; greatest breadth 

 of the former (in the equator of each chamber) 013, of the latter O09 ; pores of the external 

 cortical shell 0'002 to 0'004, of the internal O004 to O'OOS ; bars of the former 0'002, of the latter 

 0-003. 



Habitat. Pacific, central area, Stations 271, 272, depth 2425 to 2600 fathoms. 



2. Peripanartus Icevigatus, n. sp. 



Internal cortical shell with four unequal chambers, both proximal kidney-shaped (with sub- 

 regular polygonal pores, twice to three times as broad as the bars), both distal nearly hemispherical, 

 with subregular, roundish pores of half that size. External cortical shell envelops only the 

 proximal chambers, and appears as the direct continuation of the internal shell of the distal 

 chambers, with the same small roundish pores. The outer surface is quite smooth. This species 

 has nearly the same structure as Peripanicium amphicorona (PL 40, fig. 8), but differs from it by. 

 the absence of the polar spine-circles, and by the perfect smoothness of the surface. 



Dimensions. Main axis of the shell 0'25, greatest breadth (in the equator of the proximal 

 chambers) 015 ; equatorial stricture of the' external shell 010, of the internal 0'07 ; pores of the 

 internal shell of the proximal chambers 0'013, of the external O'OOG ; bars O'OOS. 



Habited. Pacific, central area, Station 274, depth 2750 fathoms. 



3. Peripanartus amphiconus, n. sp. (PL 40, fig. 5). 



Inner cortical shell with four very unequal chambers ; both proximal chambers kidney-shaped 

 (with regular, circular, hexagonally framed pores, twice as broad as the bars) ; both distal chambers 

 conical, with a circle of large square pores at the base, the other pores very small, roundish. Outer 

 cortical shell very thin, quite smooth, with irregular, roundish pores, envelops in younger specimens 

 only the distal chambers. But the radial spines on the surface of the internal cortical shell of 

 the proximal chambers indicate that these will also be afterwards enclosed by the growing of the 

 external shell. This species exhibits the progressive (ontogenetic as well as phylogenetic) develop- 

 ment of Panartus amphiconus. 



Dimensions. Main axis of the outer cortical shell 0'3, its greatest breadth (at the prominent 

 distal ends of the radial rods between the large square pores) 015 pores O'OOS to O'OOl, bars 

 O'OOS ; main axis of the inner cortical shell. 0'26, its greatest breadth 013 ; pores of its distal 

 chambers 0'003, of its proximal chambers O'Ol ; large square pores 0'03 ; bars 0'004. 



Habitat. Pacific, central area, Station 270, depth 2925 fathoms. 



