REPORT ON THE RADIOLARIA. 189 



pores ; ten to twelve on the half meridian. Bars as broad as the pores. Outer sheU regularly 

 octahedral, with eight triangular perfectly regular even faces, separated by eight prominent edges ; 

 the meshes circular, regular, about twelve to fourteen on the. half meridian, two to three times as 

 broad as the bars between them. Six strong radial spines, about as long as the diameter of the 

 outer shell, three-sided prismatic, cuspidate ; tlieu- three edges prominent, serrate, spirally twisted. 

 Each spine bears about its middle three strong flattened lateral branches, nearly perpendicular to 

 it, not serrated, and slightly curved. 



Dimensions. — Diameter of the outer shell 013, inner 0'045 ; pores of the former O'Ol, of the 

 latter 0-004 ; length of the spine 012, breadth 0-014. 



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



4. Hexancistra quadricuspis, n. sp. (PI. 22, fig. 11). 



Cortical shell thin walled, covered with short bristle-shaped by-spines, three and a half times as 

 broad as the medullary shell. Pores of the latter regular circular, small ; pores of the former three 

 to six times as large, very irregular, roundish, double-edged. Six radial spines, three-sided pris- 

 matic, about as long as the shell diameter, with three wing-like, slightly twisted edges, which are 

 prolonged towards the distal end into three curved horn-shaped branches. 



Dimensions. — Diameter of the outer shell 0-17, inner 0-05 ; cortical pores O'Ol to 0'03, 

 bars 0"005 ; medullary pores 0-003, bars 0-001 ; length of the spines 0'15, breadth 0-013. 



Habitat. — Central Pacific, Station 271, depth 2425 fathoms. 



Subgenus 2.^'-liexapitys, Haeckel, 1881, Prodromus, p. 451. 



Definition. — Eacli radial spine with three rows of verticillate hxteral branches (a 

 row arising from each edge of the spine). 



5. Hexancistra mirabilis, n. sp. (PI. 23, fig. 3). 



Hexapitys mirabilis, 'S.&^akii\, 1881, Prodromus, p. 451. 



Cortical shell very thin waUed, three times as broad as the medullary sheU. Inner shell 

 spherical, with very delicate, subregular hexagonal, meshes ; seven to eight on the half diameter-. 

 Outer shell octahedral, with irregular polygonal meshes of very chfi'erent size ; on the surface 

 numerous tliin accessory radial spines, equal in length to its rachus. Six main spines, extremely 

 long and stout, many times longer than tlie diameter of the outer shell, nearly as broad as the 

 radius of the inner shell, three-sided prismatic, with sharp, prominent, spirally twisted edges ; 

 on every edge a great number of thin lateral branches, arranged perpendicularly to it, as long as the 

 diameter of the outer shell, and pinnated by ten to twenty pairs of delicate secondary spinules, 

 biserial and perpeudicidar to the primary branches. (In the figured specimen the spherical 

 central capsule, between both shells, was well preserved ; its nucleus nearly filled the medullar^' 

 shell. The thick jelly-veil around it was racUally striped and octahedral.) 



