REPORT ON THE RADIOLARIA. 383 



only by the exteiiial cortical shell enveloping the whole internal one, in the same naanner as in 

 Peripanartxs njlindriis (PL 40, fiji. 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 lialf as large as 

 those of the inner cortical shell. 



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

 of the former (in the equator of each chaudjer) 0'13, of the latter 0'09 ; pores of the external 

 cortical shell 0-002 to 0-004, of the internal 0-004 to 0-008 ; 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 IcBvigatus, n. sp. 



Internal cortical shell with four unequal chambers, lioth proximal kidney-shaped (with STib- 

 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 Feripanicium aviphicorona (PI. 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) 0-15 ; equatorial stricture of the external shell 0-10, of the internal 0-07 ; pores of the 

 internal shell of the proximal chambers 0-013, of the external 0-006 ; bars 0003. 



JTribif'if. — Pacific, central area. Station 274, depth 2750 fathoms. 



3. Peripcvnartus amphiconus, n. sp. (PL 40, lig. 5). 



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

 (with regular, circular, hexagonaUy 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 sinaU, roundish. Outer 

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

 only the distal cliambers. 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 amphicomts. 



Dimensions. — Main axis of the outer cortical sheU 3, its greatest breadth (at the prominent 

 distal ends of the radial rods between the large square pores) 0-15 pores 0-003 to 0-001, bars 

 0-005 ; main axis of the inner cortical shell 0-26, its greatest breadth O'lo ; pores of its distal 

 chambers 0-003, of its proximal chambers 0-01 ; large square pores 0-03 ; bars 0-004. 



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



