REPORT ON THE EADIOLAREA. 147 



The genus Stylocromyum differs from its probable ancestral form, Amphisphcera, 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 amphiconns, n. sp. 



Surface of the sliell smooth. Radial proportion of the foiir 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 sliells regular, circular, two to four times as broad 

 as the bars. Both polar sjiines eqtial, 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 meduUary shell 0'0.3, (B) outer 

 medullary shell 0-06, (C) inner cortical shell 0-25, (D) outer cortical shell 0-28 ; length of the 

 polar spines 0'3, basal breadth O03. 



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



2. Stylocromyum amphipjyramis, n. sp. 



Surface of the shell smcxith. Radial proportion of the four spheres = 2:3:6:8. Both 

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

 irregidar, roundish, much larger poi'es, 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.— Did^meiQY of the four spheres— (A) 0-04, (B) 0-06, (C) 042, (D) 046 ; length of the 

 polar spines 041, basal breadth 0'02. 



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



Genus 55. Cromyostylus,^ Haeckel, 1881, Prodromus, p. 453. 



Definition. — Sty lo sphger ida with four concentric lattice-spheres and two free 

 spines of cUiferent size or form. 



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

 differentiation of the two unequal polar spines. 



1. Cromyostylus gladius, n. sp. 



Sirrface of the shell smooth. Radial proportion of the four spheres = l : 3 : 10 : 12. Both 

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

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



' Cromyostybis = Onion with styles ; K^oiivou, otuAo;. 



