REPORT ON THE RADIOLARIA. 499 



1. Perichlamydium praetextum, Ehrenberg. 



Perichlamydium praetextum, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 



p. 43; MikrogeoL, 1854, Taf. xxii. fig. 21 (non 20). 

 PeriMamydium praetextum, Haeckel, 1862, Monogr. d. Eadiol., p. 495. 



All rings of the disk (three to four) concentric, circular, of equal breadth, with interrupted (not 

 piercing) radial beams. Equatorial girdle without radial beams, nearly as broad as the disk ; its 

 circular pores of the same size as those of the disk ; about two pores on the breadth of each ring. 



Dimensions. Diameter of the disk (without the girdle, with four rings) O'll ; breadth of each 

 ring 0-012 ; breadth of the girdle 0'06 to 01 ; pores 0'004. 



Habitat. Cosmopolitan ; Atlantic, Indian, Pacific, surface ; also fossil in the Tertiary rocks 

 of Barbados and Sicily. 



2. Perichlamydium saturnus, n. sp. (PI. 41, fig. 5). 



All rings of the disk (three to four) concentric, circular (sometimes partly concentric, circular, 

 partly spiral, or irregular), with interrupted (not piercing) radial beams. Equatorial girdle without 

 radial beams, about half as broad as the disk ; its circular pores very small, scarcely half as large as 

 those of the disk ; about three pores on the breadth of each ring. (Very variable in the ring-form, 

 differs from the preceding in the small pores of the girdle.) 



Dimensions. Diameter of the disk (without the girdle, with three rings) O'll ; breadth of each 

 ring 0-02, pores 0'004, breadth of the girdle 0'05, pores 0'002. 



Habitat. Pacific, central area, Station 265, depth 2900 fathoms. 



3. Perichlamydium accrescens, Haeckel. 



Discospira accrescens, Stohr, 1880, Palseontogr., vol. xxvi. p. 114, Taf. vi. fig. 5. 



All rings of the disk (six to seven) not concentric, convoluted in a simple spiral, of nearly equal 

 breadth, with interrupted (not piercing) radial beams. Equatorial girdle in the proximal part with 

 numerous radial beams, which do not reach its margin ; its pores half as large as those of the disk, 

 where one to two pores arise on the breadth of each ring. (The girdle becomes twice to three times 

 as broad as in the figure of Stohr.) 



Dimensions. Diameter of the disk (with seven rings, without the girdle) 013 ; breadth of each 

 ring 0-007 to O'Ol ; pores 0'0036 ; breadth of the girdle 0'05, pores of it O'OOlY. 



Habitat. Fossil in Tertiary rocks of Sicily, Grotte (Stohr), Caltanisetta (Haeckel) ; living in the 

 Central Pacific, Station 266, depth 2750 fathoms. 



4. Perichlamydium spirals, Ehrenberg. 



Periclilamydium spirale, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. 

 fig. 12. 



All rings of the disk (three to four) not concentric, convoluted in a simple spiral, of increasing 

 breadth from the centre ; connected by numerous piercing radial beams. Equatorial girdle about 



