1700 THE VOYAGE OF H.M.S. CHALLENGER. 



sometimes six) ovate, basal pores (fig. 3&). Mouth armed with a corona of eight short, conical, 

 vertical, spinulate teeth (fig. 3a). 



Dimensions. Diameter of the shell 0'4 to 0'5, length of the spines 0'2 to 0'25. 



Habitat. South-Eastern Pacific (off Valparaiso), Station 298, depth 2225 fathoms. 



2. Circostephanus sexagenarius, n. sp. 



Shell polyhedral, with sixty triangular, equilateral, congruent faces, which are nearly plane, and 

 separated by high prominent crests. They are disposed in twelve pentagonal groups, each with five 

 faces, so that they appear as if derived from a regular pentagonal dodecahedron, the twelve regular 

 faces of which are each divided into five congruent triangles, meeting in its centre. From the 

 elevated corners of the polyhedron arise thirty-two radial spines (twelve in the central points of 

 the pentagons, twenty in the meeting corners of every three pentagons). The. radial spines are 

 nearly as long as the diameter of the shell, cylindrical, spinulate, and surrounded at the distal -end 

 by a verticil of five stout, curved branches, and at the pyramidal base by a corona of twelve to sixteen 

 basal pores. Mouth armed with a corona of twelve conical, vertical, spinulate teeth. 



Dimensions. Diameter of the shell 0'75, length of the spines 0'6. 



Habitat. South Pacific, Station 295, depth 1500 fathoms. 



3. Circostephanus polygonarius, n. sp. 



Shell polyhedral, with sixty to eighty subregular, triangular, concave faces, which are separated 

 by prominent crests. From the elevated corners of the polyhedron arise thirty to forty radial 

 spines, which are longer than the diameter of the shell, densely covered with curved bristles and 

 three-sided prismatic, with three spirally convoluted edges. Their distal end is surrounded by a 

 verticil of eight or nine curved branches, and their pyramidal base by a corona of eight or nine basal 

 pores. Mouth armed with a corona of ten conical, vertical, spinulate teeth. 



Dimensions. Diameter of the shell 0'8, length of the spines 0'9. 



Habitat. South Pacific, Station 288, depth 2600 fathoms. 



Subfamily 2. HAECKELINIDA. 



Definition. C ircoporida with dimpled spherical shell, not composed of polygonal 

 plates. The shell is covered with small roundish dimples, never polyhedral, and the 

 radial spines are simple, not branched, and usually not regularly arranged. 



Genus 716. Haeckeliana, John Murray, 1879, in schedulis, Chall. Coll. 



Definition. C irco'porida with spherical shell of a peculiar dimpled, porcellanous 

 structure, and with a variable number of simple radial main-spines which are usually 

 not regularly arranged. 



