REPORT ON THE RADIOLARIA. 147 



The genus Stylocromyum differs from its probable ancestral form, Amphisphara, by 

 the duplication of the cortical shell ; two opposite radial beams, piercing the wall of the 

 central capsule, connect it with the double medullary shell, and are prolonged outside 

 into two equal spines. 



1. Stylocromyum amphiconus, n, sp, 



Surface of the shell smooth. Radial proportion of the four spheres = 1:2:8:9. Two medul- 

 lary shells inside the central capsule, two cortical shells outside it. Interval between the second 

 and third shells the greatest. Pores of all the shells regular, circular, two to four times as broad 

 as the bars. Both polar spines equal, conical, about as- long as the axis of the outermost sphere, as 

 broad at the base as the innermost. 



Dimensions. Diameter of the four spheres -(A) inner medullary shell O03, (B) outer 

 medullary shell O06, (C) inner cortical shell 0'25, (D) outer cortical shell 0'28 ; length of the 

 polar spines 0'3, basal breadth 0'03. . 



Habitat. Central Pacific, Station 273, depth 2350 fathoms. 



2. Stylocromyum amphipyramis, n. sp. 



Surface of the shell smooth. Eadial proportion of the four sp"heres = 2~: 3 : 6 : 8. Both 

 medullary shells with regular, circular pores, twice as broad as the bars. Both cortical shells with 

 irregular, roundish, much larger pores, three to six times as broad as the bars. Both polar spines 

 equal or nearly equal, three-sided pyramidal, about as long as the axis of the third shell. 



Dimensions. Diameter of the four spheres (A) O04, (B) 0'06, (C) 012, (D) 016 ; length of the 

 polar spines Oil, basal breadth - 02. 



Habitat. Central Pacific, Station 265, depth 2900 fathoms. 



Genus 55. Cromyostylus, 1 Haeckel, 1881, Prodromus, p. 45-3. 



Definition. Stylosphserida with four concentric lattice-spheres and two free 

 spines of different size or form. 



The genus Cromyostylus differs from its ancestral form, Stylocromyum, in the 

 differentiation of the two unequal polar spines. 



1. Cromyostylus gladius, n. sp. 



Surface of the shell smooth. Eadial proportion of the four spheres 1 : 3 : 10 : 12. Both 

 medullary shells with regular, circular, simple pores. Inner cortical shell with regular, circular, 

 hexagonally framed pores, twice as broad as the bars. From each hexagon-corner arises a bristle- 



1 Cromyostylus = Onion with styles ; xgofiv&v, <rrJ?io?. 



