REPORT ON THE RADIOLARIA. 505 



Dimensions. Diameter of the disk (with six rings) 0'14 ; breadth of each ring O'Ol to 0'012 ; 

 pores 0-002 to 0'006. 



Habitat. Pacific, central area, Station 272, depth 2600 fathoms. 



Genus 219. Tripodictya, 1 Haeckel, 1881, Prodromus, p. 460. 



Definition. P orodiscida with three solid, equidistant, radial spines on the 

 margin of the circular or triangular disk. 



The genus Tripodictya exhibits three radial spines on the margin of the disk, 

 divergent at equal angles ; rarely in some specimens the angles differ more or less. 

 Perhaps this genus bears a near relation to the Dictyastrida (or to the Euchitonida 

 with three chambered arms Dictyastrum, Euchitonia, &c.). 



1. Tripodictya trigonaria, n. sp. (PI. 42, fig. 8). 



All rings of the disk concentric, triangular, with three equal convex sides, all of the same 

 breadth ; first and second rings with three simple chambers, third and fourth rings with six chambers, 

 fifth ring with twelve chambers. Central chamber also equilateral triangular, from its three corners 

 arise three piercing perradial beams ; from the second ring arise three interradial beams, alternate 

 with the latter ; from the fourth ring between these and the former arise six adradial beams. Pores 

 subregular, two on the breadth of each ring. Three marginal spines pyramidal, as long as the 

 radius of the disk and as broad as one ring. 



Dimensions. Diameter of the disk (with five rings) Oil; breadth of each ring O'Oll ; 

 pores 0'004. 



Habitat. Pacific, central area, Station 265, depth 2900 fathoms. 



2. Tripodictya triacantha, n. sp. (PI. 42, fig. 7). 



All rings of the disk concentric, circular, of the same breadth, connected by very numerous 

 irregular radial beams, the number of which increases towards the periphery. Pores irregular, 

 roundish, two on the breadth of each ring. Three marginal spines spindle-shaped, as long as the 

 radius of the disk, and in the middle part as broad as one ring. 



Dimensions. Diameter of the disk (with eight rings) 0'2 ; breadth of each ring 0'012 ; 

 pores 0-004. 



Habitat. North Pacific, Station 253, depth 3125 fathoms. 



3. Tripodictya tribelonia, n. sp. (PI. 42, g. 9). 



All rings of the disk, or a part of them, not concentric, spirally convoluted, of equal breadth, 

 connected by numerous irregular, interrupted radial beams, the number of which increases from the 

 centre. (In one marginal view of the disk, PI. 42, fig. 9, the disk seemed to be composed of seven 



1 Tripodictya = 'Ne\, with tripod ; Tf/woi;;, S/xri/ov. 



(ZOOL. CHALI> EXP. PART XL. 1885.) Rr 64 



