REPORT ON THE RADIOLARIA. 1699 



species by thirty prominent crest-like edges. From the corners of the dodecahedron, 

 at which every three pentagons meet, arise twenty radial spines, opposite in pairs in ten 

 equidistant axes. 



1. Circorrhegma dodecahedra, n. sp. (PI. 117, figs. 2, 2a). 



Shell dodecahedral, with twelve equal and regular, plane, pentagonal plates, which are separated 

 by thirty prominent crests, and bear a network of numerous polygonal (usually also pentagonal), 

 smaller plates. Twenty radial spines about as long as the radius of the shell, three-sided prismatic, 

 covered with numerous bristles; each surrounded at the thickened base by a circle of twelve to sixteen 

 pores, and at the distal apex by a corona of five curved, terminal branches. Mouth pentagonal, with 

 five conical, subvertical, spinulate teeth (fig, 2a). 



Dimensions, Diameter of the shell 0'8, length of the spines 0'5. 



Habitat. Indian Ocean, Madagascar (Rabbe). 



Genus 715. Circostephanus, 1 Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. C ircoporida with a subregular, polyhedral or nearly spherical 

 shell, composed of thirty to sixty or more triangular plates, with twenty-four to thirty- 

 two or more corners, from which arise radial spines, symmetrically disposed. 



The genus Circostephanus comprises those Circoporida in which the porcellanous 

 shell is an endospherical polyhedron, with numerous (thirty to sixty or more) triangular 

 faces, and has a variable number of radial spines (twenty -four to forty or more), arising 

 from its corners. The number of faces and corners seems to be variable in this genus, 

 but may perhaps be typical in some species. Circostephanus sexagenarius has the 

 typical form of a " Sexagenal-Polyhedron," with sixty equal triangular faces and thirty- 

 two corners, and may be derived from the " Pentagonal-Dodecahedron " (Circorrhegma) 

 by dividing its twelve pentagonal faces each into five congruent triangles. 



1. Circostephanus coronarius, n. sp. (PI. 116, figs. 3, 3a, 36). 



Shell polyhedral, with thirty- two to forty triangular, concave faces of nearly equal size, which 

 are separated by high prominent crests. From the elevated corners of the polyhedron arise twenty- 

 four to thirty radial spines, which are three- sided prismatic or nearly cylindrical, about as long as 

 the radius of the shell, and covered with long curved bristles. The distal end of each spine is 

 surrounded by a verticil of five stout, curved branches, its pyramidal base by a corona of five (or 

 1 Circostephanus= Shell with circular coronets; 



