RErOET 0^ THE RADIOLARIA. 941 



2. Archicircus monostephus, n. sp. (PI. 83, fig. 17). 



Grate circular. Ring circular, with three elegantly denticulate edges (one outer median and 

 two lateral edges). Transverse section of the ring triangular. 



Dimensions. — Diameter of the gate 0-06 to 008 ; thickness of the ring O'Ol to 0008. 

 Haiitat. — Central Pacific, Station 274, depth 2750 fathoms. 



3. Archicircus ellipsis, n. sp. 



Gate elliptical. Eing eUiptical, on the inner margin smooth, on the outer margin with fifteen 

 to twenty equal, short, simple, or slightly forked thorns. Transverse section ovate. 



Dirnensions. — Diameter of the gate 0-05 to 0-09 ; thickness of the ring O'Ol to 14. 

 EahUai. — ^Western Tropical Pacific, Station 225, depth 4475 fathoms ; also fossil in Barbados. 



4. Archicircus ovalis, n. sp. 



Gate ovate. Eing eUiptical, smooth, with three prominent, slightly distorted edges, without 

 thorns ; in the transverse section triangular. 



Dimensions. — Diameter of the gate O'OS to 0'12 ; thickness of the ring 0-006 to 0-009. 

 Habitat. — Tropical Atlantic, Station 347, depth 2250 fathoms. 



5. Archicircus mtpnopylus, n. sp. 



Gate ovate. Eing ovate, thorny, with three distorted edges, in the transverse section triangular ; 

 surface covered with numerous simple small thorns arising from the three edges. 



Dimensions. — Diameter of the gate O'l to 0-15 ; thickness of the ring O'Ol to 0-012. 

 Habitat. — Indian Ocean (iladagascar), Eabbe, surface. 



Subgenus 2. Archistep>hus, Haeckel. 



Definition. — Ring polygonal, with four to six or more prominent comers (and 

 commonly with simple spines arising from the corners). 



6. Archicircus quadratus, n. sp. 



Gate square. Eing square, with three edges and four short simple pyramidal spines on the four 

 comers, opposite in pairs in two perpendicular diameters. Transverse section triangular. 

 Dimensions. — Diameter of the gate 0-08 ; thickness of the ring 0-008. 

 Habitat. — Central Pacific, Station 265, depth 2900 fathoms. 



