REPORT ON THE RADIOLARIA. 811 



Genus 350. Pleuraspis, 1 Haeckel, 1881, Prodromus, p. 467. 



Definition. Dorataspida without perforated plates; shell composed, only of 

 the meeting branches of the two opposite apophyses, which arise from each radial spine. 

 Condyles of the branch ends bearing by-spines. 



The genus Pleuraspis has quite the same structure of the shell as the foregoing 

 Phractaspis, and differs from it only in the development of external by-spines ; 

 commonly each condyle of the branch end of the apophyses bears one zigzag 

 by-spine, which is directed parallel to the radial main-spine from which the apophyses 

 arise. Therefore each suture of the shell is armed with two divergent by- spines 

 (PL 137, fig. 4). 



Subgenus 1. Pleurasparium, Haeckel. 



Definition. Shell regularly developed with twenty-two meshes and forty sutures 

 (sometimes twenty to twenty -four meshes and thirty-six to forty-eight sutures) ; each 

 spine commonly with four branches, its two apophyses being simply forked. 



1. Pleuraspis horrida, n. sp. (PL 137, fig. 4). 



Radial spines roundish, somewhat compressed, very thick, conical, pointed at both ends, outer 

 part nearly twice as long as the inner. Two apophyses of each spine simply forked, with short and 

 broad branches and thickened condyles. Forty sutures, very broad. Twenty-two large meshes 

 three to four times as broad as the bars. By-spines much developed, as long as the radius, 

 zigzag, with alternating recurved hooks. 



Dimensions. Diameter of the shell - 15, of the meshes 0'04 to 0'06 ; breadth of the bars O'Ol 

 to 0-015. 



Habitat. Tropical Pacific (east of Philippines), Station 215, surface. 



2. Pleuraspis amphithecta, n. sp. 



Radial spines two-edged, leaf-shaped, strongly compressed, pointed at both ends ; outer half 

 longer than the inner. Two apophyses of each spine simply forked, with short and very broad 

 branches ; condyles not thickened. Forty sutures, broad. Twenty-two large meshes twice to three 

 times as broad as the bars. By-spines zigzag, half as long as the radius. (Resembles 

 Phractaspis complanata, PI. 137, fig. 1.) 



Dimensions. Diameter of the shell 012, of the meshes 0'02 to 0'03 ; bars 0'012. 



Habitat. Central Pacific, Station 274, surface. 



1 Pkwraspw= Shield formed by ribs ; a-XsSj 



