REPORT ON THE RADIOLARIA. 943 



12. Archicircus triglyphus, n. sp. 



Gate ovate. Ring hexagonal, with three prominent edges and twenty-two to twenty-four 

 simple curved spines, arising from the six corners and about as long as the diameter of the gate. 

 In the basal corner arise six to nine larger spines, protecting the basal pole of the central capsule. 

 From each of the five other corners arise three spines, diverging from the three edges. 



Dimensions. Diameter of the gate 0'07 to Oil ; thickness of the ring O'OOS to O'Oll. 



Habitat. Central Pacific, Station 268, depth 2900 fathoms. 



13. Archicircus sexangularis, n. sp. (PL 81, fig. 12). 



Gate hexagonal or subcircular. Ring hexagonal, with two sharp prominent edges and six pairs 

 of divergent spines, about as long as the radius of the gate, and arising from the two edges at the 

 six corners. The two apical and the two basal spines are simple and conical, whilst the eight 

 other spines, arising in pairs from the two dorsal and the two ventral corners, are slightly forked. 



Dimensions. Diameter of the gate 0'06 to 0'08 ; thickness of the ring O'Ol to 0'015. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



Genus 402. Lithocircus, 1 J. Muller, 1856, Monatsber. d. k. preuss. 

 Akad. d. Wiss. Berlin, p.. 484. 



Definition. S tephanida with a simple amphithect or diphragmatic ring, armed 

 with branched spines, without typical basal feet. 



The genus Lithocircus is the oldest known form of all S tephoidea, founded by 

 J. Miiller in 1856 for his Lithocircus annularis, the first species of this suborder 

 described. We retain here this cosmopolitan form as the typical representative of the 

 genus, which differs from the preceding Archicircus, its ancestral form, in the develop- 

 ment of branched radial spines. 



1. Lithocircus annularis, J. Miiller. 



Lithocircus annularis, J. Miiller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 29, 

 Taf. i. fig. 1. 



Gate circular. Ring circular, with four forked or simply branched spines, opposite in pairs in 

 two diameters, perpendicular one to the other. Spines with slender curved fork-branches, about as 

 long as the diameter of the gate. The specimen figured by J. Miiller bears a supernumerary fifth 

 spine ; numerous other specimens observed by me exhibited a regular cross of four spines. 



Dimensions. Diameter of the gate 01 to 015; length of the spines O'Ol to 018. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, surface. 



1 Lithocircus = Ring of silex ; x/do?, 



