EEPOET ON THE RADIOLARIA. 217 



irregular, polygonal pores ; twenty to thirty on the radius. Radial spines very numerous, bristle- 

 shaped, twice to three times as long as the diameter of the pores. 



Dimensions. Diameter of the shell - 3, pores O'Ol to 0'02 ; length of the spines 0'02 to 0'05. 



Habitat. Central Pacific, Station 274, surface. 



31. Acanthosphcera reticulata, n. sp. (PL 26, fig. 5). 



Rliapliidosphcera reticulata, Haeckel, 1881, Prodromus. 



Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars ; six to 

 eight on the radius. Surface of the bars covered with a peculiar delicate network of very fine 

 crests. Twenty to forty radial spines, angular, pyramidal, scarcely one-third as long as the radius 

 of the shell, as broad at the base as the bars. 



Dimensions. Diameter of the shell 0'22, pores 0'02 to 0'04, bars O'Ol ; length of the spines 

 0-04, basal breadth O'Ol. 



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



Genus 89. Heliosphcera, 1 Haeckel, 1862, Monogr. d. Radiol., p. 350 



(sensu emendato). 



Definition. A strosphserida with one simple lattice-sphere, covered with simple 

 radial spines of two different kinds : larger main spines and smaller by-spines. 



The genus Heliosphcera (in the mended definition here employed) differs from 

 the foregoing Acanthosphcera in the possession of two different kinds of radial spines : 

 larger main spines scattered on the surface or disposed regularly in limited numbers 

 (twelve to twenty, sometimes forty to fifty or more), and smaller by-spines in much 

 larger numbers, arising from all the nodal-points of the network (or sometimes also from 

 its bars). 



Subgenus 1. Heliosphcerella, Haeckel. 



Definition. Pores of the shell regular or subregular, all of nearly equal size and 

 similar form. 



1. Heliosphcera hexagonaria, n. sp. (PL 26, fig. 2). 



Shell very thin walled, about twenty times as broad as one pore. Meshes or pores subregular, 

 hexagonal, with thread-like bars ; fifteen to seventeen on the radius. Eadial spines at the nodal- 

 points of the network ; about forty main spines three-sided pyramidal, half as broad at the base as 

 one pore, and twice as long as the bristle-shaped by-spines, which are very numerous, and as long 

 as the diameter of one pore. 



1 Heliosphcera=S\m sphere ; ij?uo?, <7!p*<j*. 



(ZOOL. CHALL. BXP. PART XL. 1885.) Er 28 



